Contact Lenses, Hydrophilic
Corneal Edema
Silicones
Acanthamoeba Keratitis
Lenses
Cornea
Acanthamoeba
Corneal Ulcer
Prosthesis Fitting
Keratoconus
Aphakia
Polyethylene
Corneal Topography
Eye Infections, Bacterial
Cataract
Lens Cortex, Crystalline
Lens Capsule, Crystalline
Eyeglasses
Myopia
Polyethylenes
Disinfection
Fluorophotometry
Hydrogels
Lens Diseases
Visual Acuity
Lens Implantation, Intraocular
Fusariosis
Equipment Contamination
Presbyopia
Astigmatism
Polyhydroxyethyl Methacrylate
Methylmethacrylates
Eye Infections, Fungal
Epithelium, Corneal
Crystallins
Prosthesis Failure
Refractive Errors
Orthokeratologic Procedures
Eye Infections
Lens Subluxation
Corneal Stroma
Hyperopia
Disinfectants
Silicone Elastomers
Eye
Hygiene
Dry Eye Syndromes
Ophthalmic Solutions
Interferometry
Conjunctiva
Accommodation, Ocular
Methacrylates
Chromium Alloys
Contact Tracing
Surface Properties
Eye Proteins
Corneal Transplantation
Amebiasis
Dermatitis, Contact
Visual outcome after contact lens and intraocular lens correction of neonatal monocular aphakia in monkeys. (1/53)
PURPOSE: A monkey model was used to evaluate intraocular lenses (IOLs) and extended-wear contact lenses (EWCLs) for the optical treatment of infantile aphakia in humans. Specifically, the relative effectiveness of EWCLs used alone and IOLs used in combination with EWCLs in preventing amblyopia was assessed. METHODS: A total of 33 rhesus monkeys was studied in this project, 24 assigned to experimental treatment groups and 9 to normal controls. Contact lenses made from a diffusing material or dyed opaque were placed on one eye at birth to simulate an infantile cataract. A unilateral lensectomy was then performed on the same eye within 2.5 weeks after birth. In 15 monkeys this was combined with implantation of an IOL. The eyes were left aphakic in the remaining 9 animals. EWCLs were used to adjust the optical correction of both aphakic and pseudophakic eyes to a near point (3-5 D). Opaque lenses were used to maintain daily part-time (approximately 70%) occlusion of the fellow eye. The primary outcome measure was grating acuity assessed with behavioral methods. Some animals were also assessed for acuity with sweep visually evoked potentials (VEPs) and for optotype acuity (Landolt C) with behavioral methods. RESULTS: Two of the animals with IOLs developed complications in the eye that precluded completion of the behavioral assessment protocol. Only behavioral outcomes obtained before or in the absence of surgical complications are presented. There was a developmental delay in the maturation of grating acuity in both eyes of both treatment groups. Normal adult levels of grating acuity were eventually achieved in the group treated with IOLs combined with EWCLs. Grating acuity was significantly poorer than normal in aphakic eyes treated only with EWCLs. Comparison of the two treatment groups revealed that pseudophakic eyes treated with multifocal IOLs had significantly better gating acuity than aphakic eyes. Assessments of optotype acuity and sweep VEP acuity revealed amblyopic deficits in both pseudophakic and aphakic eyes. CONCLUSIONS: Given an absence of serious postoperative complications, neonatal correction of aphakia with IOLs combined with EWCLs can lead to normal grating acuity in a primate model. Correction with EWCLs alone was not sufficient to produce normal grating acuity. Multifocal IOL treatments combined with EWCL provided a significantly better outcome than EWCL methods alone. However, neither IOL nor EWCL methods were able to prevent amblyopia as evaluated using behavioral testing with optotypes or with sweep VEPs. (+info)Extended wear contact lens related bacterial keratitis. (2/53)
AIMS: To report the clinical findings and visual outcome of patients with extended wear contact lens (EWCL) related bacterial keratitis. METHODS: 11 cases with EWCL related bacterial keratitis were included. Corneal scrapings were obtained for cytology and cultures. RESULTS: Nine patients had unilateral bacterial keratitis and two patients showed bilateral involvement. Corneal scrapings revealed Pseudomonas aeruginosa in seven patients, Staphylococcus aureus coagulase positive in one patient, and Staphylococcus epidermidis in three patients. CONCLUSION: EWCLs may be associated with bacterial keratitis and may result in visual loss. Dispensing contact lenses by optometrists should be performed in consultation with ophthalmologists. (+info)Short term wear of high Dk soft contact lenses does not alter corneal epithelial cell size or viability. (3/53)
BACKGROUND/AIMS: Current contact lenses (CLs) when worn on an extended wear basis cause corneal epithelial alterations. The aim of this study was to evaluate changes in corneal epithelial cell morphology and physiology following short term (3 months) wear of highly oxygen permeable CLs and to compare this with disposable CLs. METHODS: Subjects were wearers of highly oxygen permeable CLs (n=11, wearing CLs on a 30 night schedule), disposable CL users (n=6, wearing CLs on a 6 night schedule), and non-CL wearers (n=20). Mean CL wear experience was 3 months. Epithelial cells were harvested using corneal cytology and were stained using acridine orange and ethidium bromide. Epithelial cell size and viability were determined. RESULTS: The majority of epithelial cells recovered were non-viable (71%), and the mean longest cell diameter was 38 (SD 8) microm. Disposable CLs caused an increase in cell size (42 (7) microm) compared with both non-wear (39 (7) microm, p=0.01) and wear of highly oxygen permeable CLs (37 (10) microm, p=0.0049). There was no difference in cell viability between groups. CONCLUSIONS: Extended wear of disposable CLs caused an 8% increase in cell diameter in harvested corneal epithelial cells following 3 months of CL wear. Cells harvested following 3 months' wear of highly oxygen permeable CLs were indistinguishable from those recovered from non-CL wearers. (+info)Combined phototherapeutic keratectomy and therapeutic contact lens for recurrent erosions in bullous keratopathy. (4/53)
AIMS: To evaluate the therapeutic effects of excimer laser phototherapeutic keratectomy (PTK) combined with therapeutic contact lens for painful recurrent corneal erosions (RCE) secondary to bullous keratopathy (BK) not suitable for penetrating keratoplasty. METHODS: Excimer laser PTK was performed prospectively in eight eyes with painful RCE due to BK visually expecting no benefit from penetrating keratoplasty. After mechanical removal of the epithelium, the corneas were ablated with 50 pulses in the central 6.5 mm zone (ablation rate 0.25 microm per pulse) and another 200 pulses for polishing the periphery. After PTK, therapeutic contact lenses were applied for 3 months. The mean follow up period after PTK was 10.9 months (ranging from 6 to 15 months). RESULTS: All patients experienced relief of their pain symptoms after the epithelium healed. Only one patient complained of occasional stinging pain with intermittent recurrence of small bullae. He refused a second treatment because the pain was much less than that before the surgery and quite tolerable. No infection or other complications were noted. CONCLUSION: PTK with deeper ablation and adjunctive therapeutic contact lens is an easy to perform and effective treatment with less recurrence rate for patients with BK and poor visual potential. (+info)Predicting extended wear complications from overnight corneal swelling. (5/53)
PURPOSE: To examine the hypothesis that the corneal overnight swelling response (ONSR) is a predictor of ocular complications in contact lens extended wear (EW). METHODS: The Berkeley Contact Lens Extended Wear Study (CLEWS) was a randomized, concurrently controlled clinical trial in which more than 200 subjects in EW with rigid gas-permeable (RGP) lenses were observed for 1 year. After adapting to EW, subjects were randomized to either medium or high oxygen-permeable (Dk) RGP lenses and underwent clinical assessments, keratometry, and corneal pachometry at 3-month intervals. RESULTS: The ONSR was directly related to lens Dk (P = 0.01) and exhibited substantial variability across subjects. The probability of remaining free of complications over time was not significantly lower for subjects with a mild ONSR compared with those with greater edema (P = 0.84). The risk of development of keratopathy was not significantly related to the ONSR (relative risk = 1.00). CONCLUSIONS: The corneal ONSR is not a good predictor of ocular complications in 1 year of RGP EW. Lenses that cause little or no corneal edema are not necessarily safer for overnight wear. (+info)Impact of rigid gas-permeable contact lens extended wear on corneal epithelial barrier function. (6/53)
PURPOSE: To measure the effect of hypoxia and eye closure on epithelial permeability to fluorescein (P(dc)) during rigid lens extended wear (EW). METHODS: Central corneal thickness (CT) and P(dc) were measured in 42 subjects with an optical pachometer and automated scanning fluorophotometer, respectively. All subjects had been successfully wearing rigid gas-permeable (RGP) lenses on a 6-night EW regimen, and each individual was randomized to wear either medium- or high-oxygen-permeable (Dk) RGP lenses (two types of siloxane-fluorocarbon polymer lenses with Dk of 49 and 92). CT and P(dc) measurements were performed at an afternoon visit (baseline) and were repeated in the morning after 8 hours of overnight wear. Subjects slept with a patch over the right eye. The patch was not removed until immediately before the morning measurement. RESULTS: The mean overnight swelling response for subjects in the medium-Dk group was greater than that in the high-Dk group. Results of a paired t-test indicate that the eye wearing the medium-Dk lens with a patch overnight had a significant increase in epithelial permeability. Results of mixed-effect models suggest that eye closure and lens-induced hypoxia are significant factors in altering P(dc). CONCLUSIONS: The results indicate that corneal epithelial permeability increases with hypoxic dose and that epithelial barrier function is impaired by overnight rigid lens wear. (+info)Patterns of mucin adherence to contact lenses. (7/53)
PURPOSE: Contact lens wear alters the preocular fluid through factors that include tear deposits on the lens. In the current study, lens-adherent material was extracted to assess whether contact lenses sample mucins from the preocular fluid. METHODS: Discarded extended-wear contact lenses were collected from patients with no ocular surface disease. Mucins were extracted in guanidine hydrochloride (GuHCl) with protease inhibitors. After the supernatant was removed, the extraction was repeated twice with the addition of 10 mM dithiothreitol, making a total of three extractions. Mucins were isolated by cesium chloride (CsCl) gradient centrifugation and size fractionated on Sepharose CL2B. Charge distribution was analyzed on ion-exchange chromatography with a lithium perchlorate (LiClO(4)) gradient. RESULTS: Contact lens-adherent mucins comprised soluble mucins and mucins that required solubilization by (repeated) dithiothreitol treatment. MUC1, MUC4, MUC2, and MUC5AC mucins eluted mainly at low buoyant densities in extractions from lenses worn long term without disinfection and at successively higher buoyant densities from monthly disposable contact lenses. Mucins with little negative charge, which were observed in all extractions, and very highly negatively charged species, present in the second and third extractions from contact lenses, had no equivalents in tissue-extracted mucins. CONCLUSIONS: Mucins adhering to contact lenses are altered forms of intracellular mucins. Different degrees of adherence of mucins to contact lenses may occur, either because of mucin characteristics or after mucin complexation with adherent materials. In the context of good contact lens hygiene, their presence may offer some protection from toxicants in the tear film, because mucins could function as acceptors for charged moieties such as free radicals. (+info)Vertical movement of epithelial basal cells toward the corneal surface during use of extended-wear contact lenses. (8/53)
PURPOSE: To study the effects of extended contact lens wear (EW) on the movement of basal epithelial cells toward the corneal surface. METHODS: Rabbits (n = 32) were injected with 5-bromo-2-deoxyuridine (BrdU) to label a group of proliferating basal epithelial cells, and, 24 hours later, one randomly chosen eye was fitted with a low- or medium-oxygen-transmissible (Dk/t) rigid gas permeable (RGP) contact lens, while the other eye served as the control (n = 28). Four rabbits were not fitted with any contact lens. Rabbits were euthanatized at different time points and the corneal epithelium was immunocytochemically stained for BrdU and/or Ki-67 and counterstained with propidium iodide or Syto 59. Corneal flatmount tissues were examined three dimensionally under a laser confocal microscope and the location of each BrdU-labeled cell in the corneal epithelium (basal or suprabasal) was determined. RESULTS: Four days after injection of BrdU, both low- (P < 0.001) and medium-Dk/t RGP (P < 0.001) lens groups showed significantly more BrdU-labeled cells in the basal cell layer than in the control eyes. Six days after injection of BrdU, a small percentage of BrdU-labeled cells (<0.5%) were Ki-67 positive. CONCLUSIONS: Within 6 days, the majority (80%) of BrdU-labeled basal cells became terminally differentiated and rarely divided secondarily in the central epithelium. Short-term use of low- and medium-Dk/t RGP EW contact lenses slows the normal movement of basal epithelial cells toward the surface in the central cornea. This is consistent with known EW-lens-induced decreases in corneal epithelial basal cell proliferation and surface cell exfoliation. Overall, the data suggest that EW lenses significantly inhibit the normal homeostatic turnover rate of the corneal epithelium. (+info)Extended-wear contact lenses are a type of contact lens that is designed to be worn continuously, including during sleep, for an extended period of time. These lenses are typically made from materials that allow more oxygen to reach the eye, reducing the risk of eye irritation and infection compared to traditional overnight wear of non-extended wear lenses.
Extended-wear contact lenses can be worn for up to 30 days or longer, depending on the specific lens material and the individual's tolerance. However, it is important to note that even extended-wear contacts come with some risks, including a higher risk of eye infections and corneal ulcers compared to daily wear lenses. Therefore, it is essential to follow the recommended wearing schedule and replacement schedule provided by an eye care professional, as well as to have regular eye exams to monitor the health of the eyes.
Contact lenses are thin, curved plastic or silicone hydrogel devices that are placed on the eye to correct vision, replace a missing or damaged cornea, or for cosmetic purposes. They rest on the surface of the eye, called the cornea, and conform to its shape. Contact lenses are designed to float on a thin layer of tears and move with each blink.
There are two main types of contact lenses: soft and rigid gas permeable (RGP). Soft contact lenses are made of flexible hydrophilic (water-absorbing) materials that allow oxygen to pass through the lens to the cornea. RGP lenses are made of harder, more oxygen-permeable materials.
Contact lenses can be used to correct various vision problems, including nearsightedness, farsightedness, astigmatism, and presbyopia. They come in different shapes, sizes, and powers to suit individual needs and preferences. Proper care, handling, and regular check-ups with an eye care professional are essential for maintaining good eye health and preventing complications associated with contact lens wear.
Hydrophilic contact lenses are a type of contact lens that is designed to absorb and retain water. These lenses are made from materials that have an affinity for water, which helps them to remain moist and comfortable on the eye. The water content of hydrophilic contact lenses can vary, but typically ranges from 30-80% by weight.
Hydrophilic contact lenses are often used to correct refractive errors such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. They can be made in a variety of materials, including soft hydrogel and silicone hydrogel.
One advantage of hydrophilic contact lenses is that they tend to be more comfortable to wear than other types of contacts, as they retain moisture and conform closely to the shape of the eye. However, they may also be more prone to deposits and buildup, which can lead to protein accumulation and discomfort over time. Proper care and cleaning are essential to maintain the health of the eyes when wearing hydrophilic contact lenses.
Disposable equipment in a medical context refers to items that are designed to be used once and then discarded. These items are often patient-care products that come into contact with patients or bodily fluids, and are meant to help reduce the risk of infection transmission. Examples of disposable medical equipment include gloves, gowns, face masks, syringes, and bandages.
Disposable equipment is intended for single use only and should not be reused or cleaned for reuse. This helps ensure that the equipment remains sterile and free from potential contaminants that could cause harm to patients or healthcare workers. Proper disposal of these items is also important to prevent the spread of infection and maintain a safe and clean environment.
Contact lens solutions are a type of disinfecting and cleaning solution specifically designed for use with contact lenses. They typically contain a combination of chemicals, such as preservatives, disinfectants, and surfactants, that work together to clean, disinfect, and store contact lenses safely and effectively.
There are several types of contact lens solutions available, including:
1. Multipurpose solution: This type of solution is the most commonly used and can be used for cleaning, rinsing, disinfecting, and storing soft contact lenses. It contains a combination of ingredients that perform all these functions in one step.
2. Hydrogen peroxide solution: This type of solution contains hydrogen peroxide as the main active ingredient, which is a powerful disinfectant. However, it requires a special case called a neutralizer to convert the hydrogen peroxide into water and oxygen before using the lenses.
3. Saline solution: This type of solution is used only for rinsing and storing contact lenses and does not contain any disinfecting or cleaning agents. It is often used in combination with other solutions for a complete contact lens care routine.
4. Daily cleaner: This type of solution is used to remove protein buildup and other deposits from the surface of contact lenses. It should be used in conjunction with a multipurpose or hydrogen peroxide solution as part of a daily cleaning routine.
It's important to follow the manufacturer's instructions carefully when using contact lens solutions to ensure that they are used safely and effectively. Failure to do so could result in eye irritation, infection, or other complications.
Aphakia, postcataract is a medical condition that refers to the absence of the lens in the eye after cataract surgery. A cataract is a clouding of the natural lens inside the eye that can cause vision loss. During cataract surgery, the cloudy lens is removed and replaced with an artificial lens implant. However, if there is a complication during the procedure and the artificial lens is not placed in the eye or if it becomes dislocated after surgery, then the patient will develop aphakia, postcataract.
Patients with aphakia, postcataract have poor vision and may experience symptoms such as blurry vision, glare, and halos around lights. They are also at an increased risk of developing glaucoma and retinal detachment. To correct the vision in patients with aphakia, they can wear special contact lenses or glasses with high-powered lenses, or undergo a secondary surgical procedure to implant an artificial lens in the eye.
Keratitis is a medical condition that refers to inflammation of the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an essential role in focusing vision, and any damage or infection can cause significant visual impairment. Keratitis can result from various causes, including bacterial, viral, fungal, or parasitic infections, as well as trauma, allergies, or underlying medical conditions such as dry eye syndrome. Symptoms of keratitis may include redness, pain, tearing, sensitivity to light, blurred vision, and a feeling of something foreign in the eye. Treatment for keratitis depends on the underlying cause but typically includes antibiotics, antivirals, or anti-fungal medications, as well as measures to alleviate symptoms and promote healing.
Corneal edema is a medical condition characterized by the accumulation of fluid in the cornea, which is the clear, dome-shaped surface at the front of the eye. This buildup of fluid causes the cornea to swell and thicken, resulting in blurry or distorted vision. Corneal edema can be caused by various factors, including eye injuries, certain medications, eye surgeries, and diseases that affect the eye's ability to pump fluids out of the cornea. In some cases, corneal edema may resolve on its own or with treatment, but in severe cases, it may require a corneal transplant.
Corneal diseases are a group of disorders that affect the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an important role in focusing vision, and any damage or disease can cause significant visual impairment or loss. Some common types of corneal diseases include:
1. Keratoconus: A progressive disorder in which the cornea thins and bulges outward into a cone shape, causing distorted vision.
2. Fuchs' dystrophy: A genetic disorder that affects the inner layer of the cornea called the endothelium, leading to swelling, cloudiness, and decreased vision.
3. Dry eye syndrome: A condition in which the eyes do not produce enough tears or the tears evaporate too quickly, causing discomfort, redness, and blurred vision.
4. Corneal ulcers: Open sores on the cornea that can be caused by infection, trauma, or other factors.
5. Herpes simplex keratitis: A viral infection of the cornea that can cause recurrent episodes of inflammation, scarring, and vision loss.
6. Corneal dystrophies: Inherited disorders that affect the structure and clarity of the cornea, leading to visual impairment or blindness.
7. Bullous keratopathy: A condition in which the endothelium fails to pump fluid out of the cornea, causing it to swell and form blisters.
8. Corneal trauma: Injury to the cornea caused by foreign objects, chemicals, or other factors that can lead to scarring, infection, and vision loss.
Treatment for corneal diseases varies depending on the specific condition and severity of the disease. Options may include eyedrops, medications, laser surgery, corneal transplantation, or other treatments.
Tooth wear is the progressive loss of tooth structure that can occur as a result of various factors. According to the medical definition, it refers to the wearing down, rubbing away, or grinding off of the hard tissues of the teeth (enamel and dentin) due to mechanical forces or chemical processes.
There are three primary types of tooth wear:
1. Abrasion: This is the loss of tooth structure caused by friction from external sources, such as incorrect brushing techniques, bite appliances, or habits like nail-biting and pipe smoking.
2. Attrition: This type of tooth wear results from the natural wearing down of teeth due to occlusal forces during biting, chewing, and grinding. However, excessive attrition can occur due to bruxism (teeth grinding) or clenching.
3. Erosion: Chemical processes, such as acid attacks from dietary sources (e.g., citrus fruits, sodas, and sports drinks) or gastric reflux, cause the loss of tooth structure in this type of tooth wear. The enamel dissolves when exposed to low pH levels, leaving the dentin underneath vulnerable to further damage.
Professional dental examination and treatment may be necessary to address significant tooth wear and prevent further progression, which can lead to sensitivity, pain, and functional or aesthetic issues.
Silicones are not a medical term, but they are commonly used in the medical field, particularly in medical devices and healthcare products. Silicones are synthetic polymers made up of repeating units of siloxane, which is a chain of alternating silicon and oxygen atoms. They can exist in various forms such as oils, gels, rubbers, and resins.
In the medical context, silicones are often used for their unique properties, including:
1. Biocompatibility - Silicones have a low risk of causing an adverse reaction when they come into contact with living tissue.
2. Inertness - They do not react chemically with other substances, making them suitable for use in medical devices that need to remain stable over time.
3. Temperature resistance - Silicones can maintain their flexibility and elasticity even under extreme temperature conditions.
4. Gas permeability - Some silicone materials allow gases like oxygen and water vapor to pass through, which is useful in applications where maintaining a moist environment is essential.
5. Durability - Silicones have excellent resistance to aging, weathering, and environmental factors, ensuring long-lasting performance.
Examples of medical applications for silicones include:
1. Breast implants
2. Contact lenses
3. Catheters
4. Artificial joints and tendons
5. Bandages and wound dressings
6. Drug delivery systems
7. Medical adhesives
8. Infant care products (nipples, pacifiers)
Acanthamoeba keratitis is a rare but serious infection of the cornea, which is the clear outer layer at the front of the eye. It's caused by a microscopic organism called Acanthamoeba, which is commonly found in water and soil.
The infection typically occurs in people who wear contact lenses, particularly those who do not clean and disinfect their lenses properly or who swim or shower while wearing their contacts. It can cause pain, redness, blurry vision, sensitivity to light, and a feeling like there's something in your eye.
If left untreated, Acanthamoeba keratitis can lead to serious complications, including corneal scarring, loss of vision, or even blindness. Treatment typically involves the use of specialized antimicrobial drops and sometimes requires a corneal transplant in severe cases. Prevention measures include proper contact lens hygiene, avoiding swimming or showering while wearing contacts, and regularly replacing contact lens storage cases.
In the context of medical terminology, "lenses" generally refers to optical lenses used in various medical devices and instruments. These lenses are typically made of glass or plastic and are designed to refract (bend) light in specific ways to help magnify, focus, or redirect images. Here are some examples:
1. In ophthalmology and optometry, lenses are used in eyeglasses, contact lenses, and ophthalmic instruments to correct vision problems like myopia (nearsightedness), hypermetropia (farsightedness), astigmatism, or presbyopia.
2. In surgical microscopes, lenses are used to provide a magnified and clear view of the operating field during microsurgical procedures like ophthalmic, neurosurgical, or ENT (Ear, Nose, Throat) surgeries.
3. In endoscopes and laparoscopes, lenses are used to transmit light and images from inside the body during minimally invasive surgical procedures.
4. In ophthalmic diagnostic instruments like slit lamps, lenses are used to examine various structures of the eye in detail.
In summary, "lenses" in medical terminology refer to optical components that help manipulate light to aid in diagnosis, treatment, or visual correction.
The cornea is the clear, dome-shaped surface at the front of the eye. It plays a crucial role in focusing vision. The cornea protects the eye from harmful particles and microorganisms, and it also serves as a barrier against UV light. Its transparency allows light to pass through and get focused onto the retina. The cornea does not contain blood vessels, so it relies on tears and the fluid inside the eye (aqueous humor) for nutrition and oxygen. Any damage or disease that affects its clarity and shape can significantly impact vision and potentially lead to blindness if left untreated.
Acanthamoeba is a genus of free-living, ubiquitous amoebae found in various environments such as soil, water, and air. These microorganisms have a characteristic morphology with thin, flexible pseudopods and large, rounded cells that contain endospores. They are known to cause two major types of infections in humans: Acanthamoeba keratitis, an often painful and potentially sight-threatening eye infection affecting the cornea; and granulomatous amoebic encephalitis (GAE), a rare but severe central nervous system infection primarily impacting individuals with weakened immune systems.
Acanthamoeba keratitis typically occurs through contact lens wearers accidentally introducing the organism into their eyes, often via contaminated water sources or inadequately disinfected contact lenses and solutions. Symptoms include eye pain, redness, sensitivity to light, tearing, and blurred vision. Early diagnosis and treatment are crucial for preventing severe complications and potential blindness.
Granulomatous amoebic encephalitis is an opportunistic infection that affects people with compromised immune systems, such as those with HIV/AIDS, cancer, or organ transplant recipients. The infection spreads hematogenously (through the bloodstream) to the central nervous system, where it causes inflammation and damage to brain tissue. Symptoms include headache, fever, stiff neck, seizures, altered mental status, and focal neurological deficits. GAE is associated with high mortality rates due to its severity and the challenges in diagnosing and treating the infection effectively.
Prevention strategies for Acanthamoeba infections include maintaining good hygiene practices, regularly replacing contact lenses and storage cases, using sterile saline solution or disposable contact lenses, and avoiding swimming or showering while wearing contact lenses. Early detection and appropriate medical intervention are essential for managing these infections and improving patient outcomes.
A corneal ulcer is a medical condition that affects the eye, specifically the cornea. It is characterized by an open sore or lesion on the surface of the cornea, which can be caused by various factors such as bacterial or fungal infections, viruses, or injury to the eye.
The cornea is a transparent tissue that covers the front part of the eye and protects it from harmful particles, bacteria, and other foreign substances. When the cornea becomes damaged or infected, it can lead to the development of an ulcer. Symptoms of a corneal ulcer may include pain, redness, tearing, sensitivity to light, blurred vision, and a white spot on the surface of the eye.
Corneal ulcers require prompt medical attention to prevent further damage to the eye and potential loss of vision. Treatment typically involves antibiotics or antifungal medications to eliminate the infection, as well as pain management and measures to protect the eye while it heals. In severe cases, surgery may be necessary to repair the damage to the cornea.
In medical terms, "tears" are a clear, salty liquid that is produced by the tear glands (lacrimal glands) in our eyes. They serve to keep the eyes moist, protect against dust and other foreign particles, and help to provide clear vision by maintaining a smooth surface on the front of the eye. Tears consist of water, oil, and mucus, which help to prevent evaporation and ensure that the tears spread evenly across the surface of the eye. Emotional or reflexive responses, such as crying or yawning, can also stimulate the production of tears.
Dental restoration wear refers to the progressive loss of structure and function of a dental restoration, such as a filling or crown, due to wear and tear over time. This can be caused by factors such as chewing, grinding, or clenching of teeth, as well as chemical dissolution from acidic foods and drinks. The wear can lead to changes in the shape and fit of the restoration, which may result in discomfort, sensitivity, or even failure of the restoration. Regular dental check-ups are important for monitoring dental restorations and addressing any issues related to wear before they become more serious.
Prosthesis fitting is the process of selecting, designing, fabricating, and fitting a prosthetic device to replace a part of an individual's body that is missing due to congenital absence, illness, injury, or amputation. The primary goal of prosthesis fitting is to restore the person's physical function, mobility, and independence, as well as improve their overall quality of life.
The process typically involves several steps:
1. Assessment: A thorough evaluation of the patient's medical history, physical condition, and functional needs is conducted to determine the most appropriate type of prosthesis. This may include measurements, castings, or digital scans of the residual limb.
2. Design: Based on the assessment, a customized design plan is created for the prosthetic device, taking into account factors such as the patient's lifestyle, occupation, and personal preferences.
3. Fabrication: The prosthesis is manufactured using various materials, components, and techniques to meet the specific requirements of the patient. This may involve the use of 3D printing, computer-aided design (CAD), or traditional handcrafting methods.
4. Fitting: Once the prosthesis is fabricated, it is carefully fitted to the patient's residual limb, ensuring optimal comfort, alignment, and stability. Adjustments may be made as needed to achieve the best fit and function.
5. Training: The patient receives training on how to use and care for their new prosthetic device, including exercises to strengthen the residual limb and improve overall mobility. Follow-up appointments are scheduled to monitor progress, make any necessary adjustments, and provide ongoing support.
Keratoconus is a degenerative non-inflammatory disorder of the eye, primarily affecting the cornea. It is characterized by a progressive thinning and steepening of the central or paracentral cornea, causing it to assume a conical shape. This results in irregular astigmatism, myopia, and scattering of light leading to blurred vision, visual distortions, and sensitivity to glare. The exact cause of keratoconus is unknown, but it may be associated with genetics, eye rubbing, and certain medical conditions. It typically starts in the teenage years and progresses into the third or fourth decade of life. Treatment options include glasses, contact lenses, cross-linking, and corneal transplantation in advanced cases.
Intraocular lenses (IOLs) are artificial lens implants that are placed inside the eye during ophthalmic surgery, such as cataract removal. These lenses are designed to replace the natural lens of the eye that has become clouded or damaged, thereby restoring vision impairment caused by cataracts or other conditions.
There are several types of intraocular lenses available, including monofocal, multifocal, toric, and accommodative lenses. Monofocal IOLs provide clear vision at a single fixed distance, while multifocal IOLs offer clear vision at multiple distances. Toric IOLs are designed to correct astigmatism, and accommodative IOLs can change shape and position within the eye to allow for a range of vision.
The selection of the appropriate type of intraocular lens depends on various factors, including the patient's individual visual needs, lifestyle, and ocular health. The implantation procedure is typically performed on an outpatient basis and involves minimal discomfort or recovery time. Overall, intraocular lenses have become a safe and effective treatment option for patients with vision impairment due to cataracts or other eye conditions.
Aphakia is a medical condition that refers to the absence of the lens in the eye. This can occur naturally, but it's most commonly the result of surgery to remove a cataract, a cloudy lens that can cause vision loss. In some cases, the lens may not be successfully removed or may be accidentally lost during surgery, leading to aphakia. People with aphakia typically have significant vision problems and may require corrective measures such as glasses, contact lenses, or an intraocular lens implant to improve their vision.
I'm sorry for any confusion, but "Polyethylene" is not a medical term. It is a type of synthetic plastic that is commonly used in various industrial and consumer products. Medical definitions typically refer to substances or conditions related to human health, treatment, or disease processes. If you have any questions related to medical terminology or concepts, I'd be happy to help!
Corneal topography is a non-invasive medical imaging technique used to create a detailed map of the surface curvature of the cornea, which is the clear, dome-shaped surface at the front of the eye. This procedure provides valuable information about the shape and condition of the cornea, helping eye care professionals assess various eye conditions such as astigmatism, keratoconus, and other corneal abnormalities. It can also be used in contact lens fitting, refractive surgery planning, and post-surgical evaluation.
Bacterial eye infections, also known as bacterial conjunctivitis or bacterial keratitis, are caused by the invasion of bacteria into the eye. The most common types of bacteria that cause these infections include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.
Bacterial conjunctivitis is an inflammation of the conjunctiva, the thin membrane that covers the white part of the eye and the inner surface of the eyelids. Symptoms include redness, swelling, pain, discharge, and a gritty feeling in the eye. Bacterial keratitis is an infection of the cornea, the clear front part of the eye. Symptoms include severe pain, sensitivity to light, tearing, and decreased vision.
Bacterial eye infections are typically treated with antibiotic eye drops or ointments. It is important to seek medical attention promptly if you suspect a bacterial eye infection, as untreated infections can lead to serious complications such as corneal ulcers and vision loss. Preventive measures include good hygiene practices, such as washing your hands frequently and avoiding touching or rubbing your eyes.
A hydrogel is a biomaterial that is composed of a three-dimensional network of crosslinked polymers, which are able to absorb and retain a significant amount of water or biological fluids while maintaining their structure. Hydrogels are similar to natural tissues in their water content, making them suitable for various medical applications such as contact lenses, wound dressings, drug delivery systems, tissue engineering, and regenerative medicine.
Hydrogels can be synthesized from a variety of materials, including synthetic polymers like polyethylene glycol (PEG) or natural polymers like collagen, hyaluronic acid, or chitosan. The properties of hydrogels, such as their mechanical strength, degradation rate, and biocompatibility, can be tailored to specific applications by adjusting the type and degree of crosslinking, the molecular weight of the polymers, and the addition of functional groups or drugs.
Hydrogels have shown great potential in medical research and clinical practice due to their ability to mimic the natural environment of cells and tissues, provide sustained drug release, and promote tissue regeneration.
A cataract is a clouding of the natural lens in the eye that affects vision. This clouding can cause vision to become blurry, faded, or dim, making it difficult to see clearly. Cataracts are a common age-related condition, but they can also be caused by injury, disease, or medication use. In most cases, cataracts develop gradually over time and can be treated with surgery to remove the cloudy lens and replace it with an artificial one.
Ocular refraction is a medical term that refers to the bending of light as it passes through the optical media of the eye, including the cornea and lens. This process allows the eye to focus light onto the retina, creating a clear image. The refractive power of the eye is determined by the curvature and transparency of these structures.
In a normal eye, light rays are bent or refracted in such a way that they converge at a single point on the retina, producing a sharp and focused image. However, if the curvature of the cornea or lens is too steep or too flat, the light rays may not converge properly, resulting in a refractive error such as myopia (nearsightedness), hyperopia (farsightedness), or astigmatism.
Ocular refraction can be measured using a variety of techniques, including retinoscopy, automated refraction, and subjective refraction. These measurements are used to determine the appropriate prescription for corrective lenses such as eyeglasses or contact lenses. In some cases, ocular refractive errors may be corrected surgically through procedures such as LASIK or PRK.
The crystalline lens in the eye is composed of three main parts: the capsule, the cortex, and the nucleus. The lens cortex is the outer layer of the lens, located between the capsule and the nucleus. It is made up of proteins and water, and its primary function is to help refract (bend) light rays as they pass through the eye, contributing to the focusing power of the eye.
The cortex is more flexible than the central nucleus, allowing it to change shape and adjust the focus of the eye for different distances. However, with age, the lens cortex can become less elastic, leading to presbyopia, a common age-related condition that affects the ability to focus on close objects. Additionally, changes in the lens cortex have been associated with cataracts, a clouding of the lens that can impair vision.
The crystalline lens of the eye is covered by a transparent, elastic capsule known as the lens capsule. This capsule is made up of collagen and forms the continuous outer layer of the lens. It is highly resistant to both physical and chemical insults, which allows it to protect the lens fibers within. The lens capsule is important for maintaining the shape and transparency of the lens, which are essential for proper focusing of light onto the retina.
Eyeglasses are a medical device used to correct vision problems. Also known as spectacles, they consist of frames that hold one or more lenses through which a person looks to see clearly. The lenses may be made of glass or plastic and are designed to compensate for various visual impairments such as nearsightedness, farsightedness, astigmatism, or presbyopia. Eyeglasses can be custom-made to fit an individual's face and prescription, and they come in a variety of styles, colors, and materials. Some people wear eyeglasses all the time, while others may only need to wear them for certain activities such as reading or driving.
Myopia, also known as nearsightedness, is a common refractive error of the eye. It occurs when the eye is either too long or the cornea (the clear front part of the eye) is too curved. As a result, light rays focus in front of the retina instead of directly on it, causing distant objects to appear blurry while close objects remain clear.
Myopia typically develops during childhood and can progress gradually or rapidly until early adulthood. It can be corrected with glasses, contact lenses, or refractive surgery such as LASIK. Regular eye examinations are essential for people with myopia to monitor any changes in their prescription and ensure proper correction.
While myopia is generally not a serious condition, high levels of nearsightedness can increase the risk of certain eye diseases, including cataracts, glaucoma, retinal detachment, and myopic degeneration. Therefore, it's crucial to manage myopia effectively and maintain regular follow-ups with an eye care professional.
The lens nucleus, also known as the crystalline lens nucleus, is the central part of the crystalline lens in the eye. The crystalline lens is a biconvex structure located behind the iris and pupil, which helps to refract (bend) light rays and focus them onto the retina.
The lens nucleus is composed of densely packed lens fibers that have lost their nuclei and cytoplasm during differentiation. It is surrounded by the lens cortex, which consists of younger lens fiber cells that are still metabolically active. The lens nucleus is relatively avascular and receives its nutrients through diffusion from the aqueous humor in the anterior chamber of the eye.
The lens nucleus plays an important role in the accommodation process, which allows the eye to focus on objects at different distances. During accommodation, the ciliary muscles contract and release tension on the lens zonules, allowing the lens to become thicker and increase its curvature. This results in a decrease in the focal length of the lens and enables the eye to focus on nearby objects. The lens nucleus is more rigid than the cortex and helps maintain the shape of the lens during accommodation.
Changes in the lens nucleus are associated with several age-related eye conditions, including cataracts and presbyopia. Cataracts occur when the lens becomes cloudy or opaque, leading to a decrease in vision clarity. Presbyopia is a condition that affects the ability to focus on near objects and is caused by a hardening of the lens nucleus and a loss of elasticity in the lens fibers.
I believe there may be some confusion in your question as Polyethylenes are not a medical term, but rather a category of synthetic polymers commonly used in various industrial and medical applications. Here's a brief overview:
Polyethylene (PE) is a type of thermoplastic polymer made from the monomer ethylene. It is a versatile material with numerous applications due to its chemical resistance, durability, and flexibility. There are several types of polyethylenes, including:
1. Low-density polyethylene (LDPE): This type has a lower density and more branching in its molecular structure, which results in less crystallinity. LDPE is known for its flexibility and is often used in packaging films, bags, and containers.
2. High-density polyethylene (HDPE): HDPE has a higher density and less branching, resulting in greater crystallinity. It is more rigid than LDPE and is commonly used in applications such as bottles, pipes, and containers.
3. Linear low-density polyethylene (LLDPE): This type combines the flexibility of LDPE with some of the strength and rigidity of HDPE. LLDPE has fewer branches than LDPE but more than HDPE. It is often used in film applications, such as stretch wrap and agricultural films.
4. Ultra-high molecular weight polyethylene (UHMWPE): UHMWPE has an extremely high molecular weight, resulting in exceptional wear resistance, impact strength, and chemical resistance. It is commonly used in medical applications, such as orthopedic implants and joint replacements, due to its biocompatibility and low friction coefficient.
While polyethylenes are not a medical term per se, they do have significant medical applications, particularly UHMWPE in orthopedic devices.
Disinfection is the process of eliminating or reducing harmful microorganisms from inanimate objects and surfaces through the use of chemicals, heat, or other methods. The goal of disinfection is to reduce the number of pathogens to a level that is considered safe for human health. Disinfection is an important step in preventing the spread of infectious diseases in healthcare settings, food processing facilities, and other environments where there is a risk of infection transmission.
It's important to note that disinfection is not the same as sterilization, which is the complete elimination of all microorganisms, including spores. Disinfection is generally less effective than sterilization but is often sufficient for most non-critical surfaces and objects. The choice between disinfection and sterilization depends on the level of risk associated with the item or surface being treated and the intended use of that item or surface.
Fluorophotometry is a medical diagnostic technique that measures the concentration of fluorescein dye in various tissues, particularly the eye. This technique utilizes a specialized instrument called a fluorophotometer which emits light at a specific wavelength that causes the fluorescein to emit light at a longer wavelength. The intensity of this emitted light is then measured and used to calculate the concentration of fluorescein in the tissue.
Fluorophotometry is often used in ophthalmology to assess the permeability of the blood-retinal barrier, which can be helpful in diagnosing and monitoring conditions such as diabetic retinopathy, age-related macular degeneration, and uveitis. It may also have applications in other medical fields for measuring the concentration of fluorescent markers in various tissues.
Hydrogels are defined in the medical and biomedical fields as cross-linked, hydrophilic polymer networks that have the ability to swell and retain a significant amount of water or biological fluids while maintaining their structure. They can be synthesized from natural, synthetic, or hybrid polymers.
Hydrogels are known for their biocompatibility, high water content, and soft consistency, which resemble natural tissues, making them suitable for various medical applications such as contact lenses, drug delivery systems, tissue engineering, wound dressing, and biosensors. The physical and chemical properties of hydrogels can be tailored to specific uses by adjusting the polymer composition, cross-linking density, and network structure.
Lens diseases refer to conditions that affect the lens of the eye, which is a transparent structure located behind the iris and pupil. The main function of the lens is to focus light onto the retina, enabling clear vision. Here are some examples of lens diseases:
1. Cataract: A cataract is a clouding of the lens that affects vision. It is a common age-related condition, but can also be caused by injury, disease, or medication.
2. Presbyopia: This is not strictly a "disease," but rather an age-related change in the lens that causes difficulty focusing on close objects. It typically becomes noticeable in people over the age of 40.
3. Lens dislocation: This occurs when the lens slips out of its normal position, usually due to trauma or a genetic disorder. It can cause vision problems and may require surgical intervention.
4. Lens opacity: This refers to any clouding or opacification of the lens that is not severe enough to be considered a cataract. It can cause visual symptoms such as glare or blurred vision.
5. Anterior subcapsular cataract: This is a type of cataract that forms in the front part of the lens, often as a result of injury or inflammation. It can cause significant visual impairment.
6. Posterior subcapsular cataract: This is another type of cataract that forms at the back of the lens, often as a result of diabetes or certain medications. It can also cause significant visual impairment.
Overall, lens diseases can have a significant impact on vision and quality of life, and may require medical intervention to manage or treat.
Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.
Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.
It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.
Intraocular lens (IOL) implantation is a surgical procedure that involves placing a small artificial lens inside the eye to replace the natural lens that has been removed. This procedure is typically performed during cataract surgery, where the cloudy natural lens is removed and replaced with an IOL to restore clear vision.
During the procedure, a small incision is made in the eye, and the cloudy lens is broken up and removed using ultrasound waves or laser energy. Then, the folded IOL is inserted through the same incision and positioned in the correct place inside the eye. Once in place, the IOL unfolds and is secured into position.
There are several types of IOLs available, including monofocal, multifocal, toric, and accommodating lenses. Monofocal lenses provide clear vision at one distance, while multifocal lenses offer clear vision at multiple distances. Toric lenses correct astigmatism, and accommodating lenses can change shape to focus on objects at different distances.
Overall, intraocular lens implantation is a safe and effective procedure that can help restore clear vision in patients with cataracts or other eye conditions that require the removal of the natural lens.
Fusariosis is a rare but serious invasive fungal infection caused by the Fusarium species, a type of filamentous fungi that are commonly found in the environment, particularly in soil and plants. The infection can affect various organs and tissues, including the lungs, sinuses, skin, nails, and internal organs such as the brain, heart, and kidneys.
Fusariosis is often difficult to diagnose due to its nonspecific symptoms and the challenges of detecting the fungus in clinical samples. The infection can occur in people with weakened immune systems, such as those undergoing chemotherapy, organ transplantation, or treatment with immunosuppressive drugs.
The severity of fusariosis varies depending on the site of infection and the patient's underlying health status. In some cases, it can cause severe illness and even death, especially in patients with prolonged neutropenia (low white blood cell count) or other serious medical conditions. Treatment typically involves antifungal medications, such as voriconazole or amphotericin B, and sometimes surgical debridement of infected tissues.
Equipment contamination in a medical context refers to the presence of harmful microorganisms, such as bacteria, viruses, or fungi, on the surfaces of medical equipment or devices. This can occur during use, storage, or transportation of the equipment and can lead to the transmission of infections to patients, healthcare workers, or other individuals who come into contact with the contaminated equipment.
Equipment contamination can occur through various routes, including contact with contaminated body fluids, airborne particles, or environmental surfaces. To prevent equipment contamination and the resulting infection transmission, it is essential to follow strict infection control practices, such as regular cleaning and disinfection of equipment, use of personal protective equipment (PPE), and proper handling and storage of medical devices.
Presbyopia is a age-related eye condition, typically occurring after the age of 40, where the lens of the eye loses its flexibility and makes it difficult to focus on near objects. This results in blurred vision when reading, sewing or focusing on other close-up tasks. It's a natural part of the aging process and is not a disease. Corrective measures such as reading glasses, bifocals, multifocal lenses or contact lenses, or refractive surgery can help manage this condition.
Astigmatism is a common eye condition that occurs when the cornea or lens has an irregular shape, causing blurred or distorted vision. The cornea and lens are typically smooth and curved uniformly in all directions, allowing light to focus clearly on the retina. However, if the cornea or lens is not smoothly curved and has a steeper curve in one direction than the other, it causes light to focus unevenly on the retina, leading to astigmatism.
Astigmatism can cause blurred vision at all distances, as well as eye strain, headaches, and fatigue. It is often present from birth and can be hereditary, but it can also develop later in life due to eye injuries or surgery. Astigmatism can be corrected with glasses, contact lenses, or refractive surgery such as LASIK.
Polyhydroxyethyl Methacrylate (PHEMA) is not a medical term itself, but a chemical compound that is used in various medical and biomedical applications. Therefore, I will provide you with a chemical definition of PHEMA:
Polyhydroxyethyl Methacrylate (PHEMA) is a type of synthetic hydrogel, which is a cross-linked polymer network with the ability to absorb and retain significant amounts of water or biological fluids. It is made by polymerizing the methacrylate monomer, hydroxyethyl methacrylate (HEMA), in the presence of a crosslinking agent. The resulting PHEMA material has excellent biocompatibility, making it suitable for various medical applications such as contact lenses, drug delivery systems, artificial cartilage, and wound dressings.
Methyl Methacrylates (MMA) are a family of synthetic materials that are commonly used in the medical field, particularly in orthopedic and dental applications. Medically, MMA is often used as a bone cement to fix prosthetic implants, such as artificial hips or knees, into place during surgeries.
Methyl methacrylates consist of a type of acrylic resin that hardens when mixed with a liquid catalyst. This property allows it to be easily molded and shaped before it sets, making it ideal for use in surgical procedures where precise positioning is required. Once hardened, MMA forms a strong, stable bond with the bone, helping to secure the implant in place.
It's important to note that while MMA is widely used in medical applications, there have been concerns about its safety in certain situations. For example, some studies have suggested that high levels of methyl methacrylate fumes released during the setting process may be harmful to both patients and surgical staff. Therefore, appropriate precautions should be taken when using MMA-based products in medical settings.
Fungal eye infections, also known as fungal keratitis or ocular fungal infections, are caused by the invasion of fungi into the eye. The most common types of fungi that cause these infections include Fusarium, Aspergillus, and Candida. These infections can affect any part of the eye, including the cornea, conjunctiva, sclera, and vitreous humor.
Fungal eye infections often present with symptoms such as redness, pain, sensitivity to light, tearing, blurred vision, and discharge. In severe cases, they can lead to corneal ulcers, perforation of the eye, and even blindness if left untreated. Risk factors for fungal eye infections include trauma to the eye, contact lens wear, immunosuppression, and pre-existing eye conditions such as dry eye or previous eye surgery.
Diagnosis of fungal eye infections typically involves a thorough eye examination, including visual acuity testing, slit lamp examination, and sometimes corneal scrapings for microbiological culture and sensitivity testing. Treatment usually involves topical antifungal medications, such as natamycin or amphotericin B, and in some cases may require oral or intravenous antifungal therapy. In severe cases, surgical intervention may be necessary to remove infected tissue or repair any damage caused by the infection.
The corneal epithelium is the outermost layer of the cornea, which is the clear, dome-shaped surface at the front of the eye. It is a stratified squamous epithelium, consisting of several layers of flat, scale-like cells that are tightly packed together. The corneal epithelium serves as a barrier to protect the eye from microorganisms, dust, and other foreign particles. It also provides a smooth surface for the refraction of light, contributes to the maintenance of corneal transparency, and plays a role in the eye's sensitivity to touch and pain. The corneal epithelium is constantly being renewed through the process of cell division and shedding, with new cells produced by stem cells located at the limbus, the border between the cornea and the conjunctiva.
Crystallins are the major proteins found in the lens of the eye in vertebrates. They make up about 90% of the protein content in the lens and are responsible for maintaining the transparency and refractive properties of the lens, which are essential for clear vision. There are two main types of crystallins, alpha (α) and beta/gamma (β/γ), which are further divided into several subtypes. These proteins are highly stable and have a long half-life, which allows them to remain in the lens for an extended period of time. Mutations in crystallin genes have been associated with various eye disorders, including cataracts and certain types of glaucoma.
Prosthesis failure is a term used to describe a situation where a prosthetic device, such as an artificial joint or limb, has stopped functioning or failed to meet its intended purpose. This can be due to various reasons, including mechanical failure, infection, loosening of the device, or a reaction to the materials used in the prosthesis.
Mechanical failure can occur due to wear and tear, manufacturing defects, or improper use of the prosthetic device. Infection can also lead to prosthesis failure, particularly in cases where the prosthesis is implanted inside the body. The immune system may react to the presence of the foreign material, leading to inflammation and infection.
Loosening of the prosthesis can also cause it to fail over time, as the device becomes less stable and eventually stops working properly. Additionally, some people may have a reaction to the materials used in the prosthesis, leading to tissue damage or other complications that can result in prosthesis failure.
In general, prosthesis failure can lead to decreased mobility, pain, and the need for additional surgeries or treatments to correct the problem. It is important for individuals with prosthetic devices to follow their healthcare provider's instructions carefully to minimize the risk of prosthesis failure and ensure that the device continues to function properly over time.
Refractive errors are a group of vision conditions that include nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. These conditions occur when the shape of the eye prevents light from focusing directly on the retina, causing blurred or distorted vision.
Myopia is a condition where distant objects appear blurry while close-up objects are clear. This occurs when the eye is too long or the cornea is too curved, causing light to focus in front of the retina instead of directly on it.
Hyperopia, on the other hand, is a condition where close-up objects appear blurry while distant objects are clear. This happens when the eye is too short or the cornea is not curved enough, causing light to focus behind the retina.
Astigmatism is a condition that causes blurred vision at all distances due to an irregularly shaped cornea or lens.
Presbyopia is a natural aging process that affects everyone as they get older, usually around the age of 40. It causes difficulty focusing on close-up objects and can be corrected with reading glasses, bifocals, or progressive lenses.
Refractive errors can be diagnosed through a comprehensive eye exam and are typically corrected with eyeglasses, contact lenses, or refractive surgery such as LASIK.
Eyelids are the thin folds of skin that cover and protect the front surface (cornea) of the eye when closed. They are composed of several layers, including the skin, muscle, connective tissue, and a mucous membrane called the conjunctiva. The upper and lower eyelids meet at the outer corner of the eye (lateral canthus) and the inner corner of the eye (medial canthus).
The main function of the eyelids is to protect the eye from foreign particles, light, and trauma. They also help to distribute tears evenly over the surface of the eye through blinking, which helps to keep the eye moist and healthy. Additionally, the eyelids play a role in facial expressions and non-verbal communication.
Orthokeratology, often referred to as "ortho-k," is a non-surgical procedure that uses specially designed contact lenses to temporarily reshape the cornea (the clear, dome-shaped surface at the front of the eye). The goal of orthokeratology is to flatten the cornea slightly so that it can properly focus light onto the retina and improve vision.
During an orthokeratology procedure, a patient wears specially fitted contact lenses while they sleep. These lenses gently reshape the cornea overnight, allowing the patient to see clearly during the day without needing glasses or contact lenses. The effects of orthokeratology are usually reversible and may wear off if the patient stops wearing the contact lenses regularly.
Orthokeratology is often used as an alternative to refractive surgery for people who want to correct their vision without undergoing a surgical procedure. It can be particularly useful for individuals with mild to moderate myopia (nearsightedness) and astigmatism, although it may also be used to treat other refractive errors.
It's important to note that orthokeratology is not a permanent solution for vision problems, and it does carry some risks, such as eye infections and corneal abrasions. As with any medical procedure, it's essential to consult with an eye care professional to determine whether orthokeratology is the right choice for you.
Eye infections, also known as ocular infections, are conditions characterized by the invasion and multiplication of pathogenic microorganisms in any part of the eye or its surrounding structures. These infections can affect various parts of the eye, including the conjunctiva (conjunctivitis), cornea (keratitis), eyelid (blepharitis), or the internal structures of the eye (endophthalmitis, uveitis). The symptoms may include redness, pain, discharge, itching, blurred vision, and sensitivity to light. The cause can be bacterial, viral, fungal, or parasitic, and the treatment typically involves antibiotics, antivirals, or antifungals, depending on the underlying cause.
Prosthesis design is a specialized field in medical device technology that involves creating and developing artificial substitutes to replace a missing body part, such as a limb, tooth, eye, or internal organ. The design process typically includes several stages: assessment of the patient's needs, selection of appropriate materials, creation of a prototype, testing and refinement, and final fabrication and fitting of the prosthesis.
The goal of prosthesis design is to create a device that functions as closely as possible to the natural body part it replaces, while also being comfortable, durable, and aesthetically pleasing for the patient. The design process may involve collaboration between medical professionals, engineers, and designers, and may take into account factors such as the patient's age, lifestyle, occupation, and overall health.
Prosthesis design can be highly complex, particularly for advanced devices such as robotic limbs or implantable organs. These devices often require sophisticated sensors, actuators, and control systems to mimic the natural functions of the body part they replace. As a result, prosthesis design is an active area of research and development in the medical field, with ongoing efforts to improve the functionality, comfort, and affordability of these devices for patients.
Lens subluxation, also known as lens dislocation or ectopia lentis, is a condition where the lens of the eye becomes partially or completely displaced from its normal position. The lens is held in place by tiny fibers called zonules, which can become weakened or broken due to various reasons such as genetic disorders (like Marfan syndrome, homocystinuria, and Weill-Marchesani syndrome), trauma, inflammation, or cataract surgery complications. This displacement can lead to symptoms like blurry vision, double vision, sensitivity to light, or the appearance of a shadow in the peripheral vision. In some cases, lens subluxation may not cause any noticeable symptoms and can be discovered during routine eye examinations. Treatment options depend on the severity and underlying cause of the subluxation and may include eyeglasses, contact lenses, or surgical intervention to remove and replace the displaced lens with an intraocular lens (IOL).
The corneal stroma, also known as the substantia propria, is the thickest layer of the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays a crucial role in focusing vision.
The corneal stroma makes up about 90% of the cornea's thickness and is composed of parallel bundles of collagen fibers that are arranged in regular, repeating patterns. These fibers give the cornea its strength and transparency. The corneal stroma also contains a small number of cells called keratocytes, which produce and maintain the collagen fibers.
Disorders that affect the corneal stroma can cause vision loss or other eye problems. For example, conditions such as keratoconus, in which the cornea becomes thin and bulges outward, can distort vision and make it difficult to see clearly. Other conditions, such as corneal scarring or infection, can also affect the corneal stroma and lead to vision loss or other eye problems.
Hyperopia, also known as farsightedness, is a refractive error in which the eye does not focus light directly on the retina when looking at a distant object. Instead, light is focused behind the retina, causing close-up objects to appear blurry. This condition usually results from the eyeball being too short or the cornea having too little curvature. It can be corrected with eyeglasses, contact lenses, or refractive surgery.
Disinfectants are antimicrobial agents that are applied to non-living objects to destroy or irreversibly inactivate microorganisms, but not necessarily their spores. They are different from sterilizers, which kill all forms of life, and from antiseptics, which are used on living tissue. Disinfectants work by damaging the cell wall or membrane of the microorganism, disrupting its metabolism, or interfering with its ability to reproduce. Examples of disinfectants include alcohol, bleach, hydrogen peroxide, and quaternary ammonium compounds. They are commonly used in hospitals, laboratories, and other settings where the elimination of microorganisms is important for infection control. It's important to use disinfectants according to the manufacturer's instructions, as improper use can reduce their effectiveness or even increase the risk of infection.
Silicone elastomers are a type of synthetic rubber made from silicone, which is a polymer composed primarily of silicon-oxygen bonds. They are known for their durability, flexibility, and resistance to heat, cold, and moisture. Silicone elastomers can be manufactured in various forms, including liquids, gels, and solids, and they are used in a wide range of medical applications such as:
1. Breast implants: Silicone elastomer shells filled with silicone gel are commonly used for breast augmentation and reconstruction.
2. Contact lenses: Some contact lenses are made from silicone elastomers due to their high oxygen permeability, which allows for better eye health.
3. Catheters: Silicone elastomer catheters are flexible and resistant to kinking, making them suitable for long-term use in various medical procedures.
4. Implantable drug delivery systems: Silicone elastomers can be used as a matrix for controlled release of drugs, allowing for sustained and targeted medication administration.
5. Medical adhesives: Silicone elastomer adhesives are biocompatible and can be used to attach medical devices to the skin or other tissues.
6. Sealants and coatings: Silicone elastomers can be used as sealants and coatings in medical devices to prevent leakage, improve durability, and reduce infection risk.
It is important to note that while silicone elastomers are generally considered safe for medical use, there have been concerns about the potential health risks associated with breast implants, such as capsular contracture, breast pain, and immune system reactions. However, these risks vary depending on the individual's health status and the specific type of silicone elastomer used.
The eye is the organ of sight, primarily responsible for detecting and focusing on visual stimuli. It is a complex structure composed of various parts that work together to enable vision. Here are some of the main components of the eye:
1. Cornea: The clear front part of the eye that refracts light entering the eye and protects the eye from harmful particles and microorganisms.
2. Iris: The colored part of the eye that controls the amount of light reaching the retina by adjusting the size of the pupil.
3. Pupil: The opening in the center of the iris that allows light to enter the eye.
4. Lens: A biconvex structure located behind the iris that further refracts light and focuses it onto the retina.
5. Retina: A layer of light-sensitive cells (rods and cones) at the back of the eye that convert light into electrical signals, which are then transmitted to the brain via the optic nerve.
6. Optic Nerve: The nerve that carries visual information from the retina to the brain.
7. Vitreous: A clear, gel-like substance that fills the space between the lens and the retina, providing structural support to the eye.
8. Conjunctiva: A thin, transparent membrane that covers the front of the eye and the inner surface of the eyelids.
9. Extraocular Muscles: Six muscles that control the movement of the eye, allowing for proper alignment and focus.
The eye is a remarkable organ that allows us to perceive and interact with our surroundings. Various medical specialties, such as ophthalmology and optometry, are dedicated to the diagnosis, treatment, and management of various eye conditions and diseases.
Hygiene is the science and practice of maintaining and promoting health and preventing disease through cleanliness in personal and public environments. It includes various measures such as handwashing, bathing, using clean clothes, cleaning and disinfecting surfaces, proper waste disposal, safe food handling, and managing water supplies to prevent the spread of infectious agents like bacteria, viruses, and parasites.
In a medical context, hygiene is crucial in healthcare settings to prevent healthcare-associated infections (HAIs) and ensure patient safety. Healthcare professionals are trained in infection control practices, including proper hand hygiene, use of personal protective equipment (PPE), environmental cleaning and disinfection, and safe injection practices.
Overall, maintaining good hygiene is essential for overall health and well-being, reducing the risk of illness and promoting a healthy lifestyle.
A hip prosthesis, also known as a total hip replacement, is a surgical implant designed to replace the damaged or diseased components of the human hip joint. The procedure involves replacing the femoral head (the ball at the top of the thigh bone) and the acetabulum (the socket in the pelvis) with artificial parts, typically made from materials such as metal, ceramic, or plastic.
The goal of a hip prosthesis is to relieve pain, improve joint mobility, and restore function, allowing patients to return to their normal activities and enjoy an improved quality of life. The procedure is most commonly performed in individuals with advanced osteoarthritis, rheumatoid arthritis, or other degenerative conditions that have caused significant damage to the hip joint.
There are several different types of hip prostheses available, each with its own unique design and set of benefits and risks. The choice of prosthesis will depend on a variety of factors, including the patient's age, activity level, overall health, and specific medical needs. In general, however, all hip prostheses are designed to provide a durable, long-lasting solution for patients suffering from debilitating joint pain and stiffness.
Dry eye syndrome, also known as keratoconjunctivitis sicca, is a condition characterized by insufficient lubrication and moisture of the eyes. This occurs when the tears produced by the eyes are not sufficient in quantity or quality to keep the eyes moist and comfortable. The medical definition of dry eye syndromes includes the following symptoms:
1. A gritty or sandy sensation in the eyes
2. Burning or stinging sensations
3. Redness and irritation
4. Blurred vision that improves with blinking
5. Light sensitivity
6. A feeling of something foreign in the eye
7. Stringy mucus in or around the eyes
8. Difficulty wearing contact lenses
9. Watery eyes, which may seem contradictory but can be a response to dryness
10. Eye fatigue and discomfort after prolonged screen time or reading
The causes of dry eye syndromes can include aging, hormonal changes, certain medical conditions (such as diabetes, rheumatoid arthritis, lupus, Sjogren's syndrome), medications (antihistamines, decongestants, antidepressants, birth control pills), environmental factors (dry air, wind, smoke, dust), and prolonged screen time or reading.
Treatment for dry eye syndromes depends on the severity of the condition and its underlying causes. It may include artificial tears, lifestyle changes, prescription medications, and in some cases, surgical procedures to improve tear production or drainage.
Ophthalmic solutions are sterile, single-use or multi-dose preparations in a liquid form that are intended for topical administration to the eye. These solutions can contain various types of medications, such as antibiotics, anti-inflammatory agents, antihistamines, or lubricants, which are used to treat or prevent ocular diseases and conditions.
The pH and osmolarity of ophthalmic solutions are carefully controlled to match the physiological environment of the eye and minimize any potential discomfort or irritation. The solutions may be packaged in various forms, including drops, sprays, or irrigations, depending on the intended use and administration route.
It is important to follow the instructions for use provided by a healthcare professional when administering ophthalmic solutions, as improper use can lead to eye injury or reduced effectiveness of the medication.
The endothelium of the cornea is the thin, innermost layer of cells that lines the inner surface of the cornea, which is the clear, dome-shaped structure at the front of the eye. This single layer of specialized cells is essential for maintaining the transparency and proper hydration of the cornea, allowing light to pass through it and focus on the retina.
The endothelial cells are hexagonal in shape and have tight junctions between them, creating a semi-permeable barrier that controls the movement of water and solutes between the corneal stroma (the middle layer of the cornea) and the anterior chamber (the space between the cornea and the iris). The endothelial cells actively pump excess fluid out of the cornea, maintaining a delicate balance of hydration that is critical for corneal clarity.
Damage to or dysfunction of the corneal endothelium can result in corneal edema (swelling), cloudiness, and loss of vision. Factors contributing to endothelial damage include aging, eye trauma, intraocular surgery, and certain diseases such as Fuchs' dystrophy and glaucoma.
Interferometry is not specifically a medical term, but it is used in certain medical fields such as ophthalmology and optics research. Here is a general definition:
Interferometry is a physical method that uses the interference of waves to measure the differences in phase between two or more waves. In other words, it's a technique that combines two or more light waves to create an interference pattern, which can then be analyzed to extract information about the properties of the light waves, such as their wavelength, amplitude, and phase.
In ophthalmology, interferometry is used in devices like wavefront sensors to measure the aberrations in the eye's optical system. By analyzing the interference pattern created by the light passing through the eye, these devices can provide detailed information about the shape and curvature of the cornea and lens, helping doctors to diagnose and treat various vision disorders.
In optics research, interferometry is used to study the properties of light waves and materials that interact with them. By analyzing the interference patterns created by light passing through different materials or devices, researchers can gain insights into their optical properties, such as their refractive index, thickness, and surface roughness.
Eye diseases are a range of conditions that affect the eye or visual system, causing damage to vision and, in some cases, leading to blindness. These diseases can be categorized into various types, including:
1. Refractive errors: These include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia, which affect the way light is focused on the retina and can usually be corrected with glasses or contact lenses.
2. Cataracts: A clouding of the lens inside the eye that leads to blurry vision, glare, and decreased contrast sensitivity. Cataract surgery is the most common treatment for this condition.
3. Glaucoma: A group of diseases characterized by increased pressure in the eye, leading to damage to the optic nerve and potential blindness if left untreated. Treatment includes medications, laser therapy, or surgery.
4. Age-related macular degeneration (AMD): A progressive condition that affects the central part of the retina called the macula, causing blurry vision and, in advanced stages, loss of central vision. Treatment may include anti-VEGF injections, laser therapy, or nutritional supplements.
5. Diabetic retinopathy: A complication of diabetes that affects the blood vessels in the retina, leading to bleeding, leakage, and potential blindness if left untreated. Treatment includes laser therapy, anti-VEGF injections, or surgery.
6. Retinal detachment: A separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly with surgery.
7. Amblyopia (lazy eye): A condition where one eye does not develop normal vision, often due to a misalignment or refractive error in childhood. Treatment includes correcting the underlying problem and encouraging the use of the weaker eye through patching or other methods.
8. Strabismus (crossed eyes): A misalignment of the eyes that can lead to amblyopia if not treated promptly with surgery, glasses, or other methods.
9. Corneal diseases: Conditions that affect the transparent outer layer of the eye, such as keratoconus, Fuchs' dystrophy, and infectious keratitis, which can lead to vision loss if not treated promptly.
10. Uveitis: Inflammation of the middle layer of the eye, which can cause vision loss if not treated promptly with anti-inflammatory medications or surgery.
The conjunctiva is the mucous membrane that lines the inner surface of the eyelids and covers the front part of the eye, also known as the sclera. It helps to keep the eye moist and protected from irritants. The conjunctiva can become inflamed or infected, leading to conditions such as conjunctivitis (pink eye).
Ocular accommodation is the process by which the eye changes optical power to maintain a clear image or focus on an object as its distance varies. This is primarily achieved by the lens of the eye changing shape through the action of the ciliary muscles inside the eye. When you look at something far away, the lens becomes flatter, and when you look at something close up, the lens thickens. This ability to adjust focus allows for clear vision at different distances.
Methacrylates are a group of chemical compounds that contain the methacrylate functional group, which is a vinyl group (CH2=CH-) with a carbonyl group (C=O) at the β-position. This structure gives them unique chemical and physical properties, such as low viscosity, high reactivity, and resistance to heat and chemicals.
In medical terms, methacrylates are used in various biomedical applications, such as dental restorative materials, bone cements, and drug delivery systems. For example, methacrylate-based resins are commonly used in dentistry for fillings, crowns, and bridges due to their excellent mechanical properties and adhesion to tooth structures.
However, there have been concerns about the potential toxicity of methacrylates, particularly their ability to release monomers that can cause allergic reactions, irritation, or even mutagenic effects in some individuals. Therefore, it is essential to use these materials with caution and follow proper handling and safety protocols.
Chromium alloys are materials made by combining chromium with other metals, such as nickel, cobalt, or iron. The addition of chromium to these alloys enhances their properties, making them resistant to corrosion and high temperatures. These alloys have a wide range of applications in various industries, including automotive, aerospace, and medical devices.
Chromium alloys can be classified into two main categories: stainless steels and superalloys. Stainless steels are alloys that contain at least 10.5% chromium by weight, which forms a passive oxide layer on the surface of the material, protecting it from corrosion. Superalloys, on the other hand, are high-performance alloys designed to operate in extreme environments, such as jet engines and gas turbines. They contain significant amounts of chromium, along with other elements like nickel, cobalt, and molybdenum.
Chromium alloys have several medical applications due to their excellent properties. For instance, they are used in surgical instruments, dental implants, and orthopedic devices because of their resistance to corrosion and biocompatibility. Additionally, some chromium alloys exhibit superelasticity, a property that allows them to return to their original shape after being deformed, making them suitable for use in stents and other medical devices that require flexibility and durability.
Contact tracing is a key public health strategy used to control the spread of infectious diseases. It involves identifying and monitoring individuals (contacts) who have come into close contact with an infected person (case), to prevent further transmission of the disease. The process typically includes:
1. Case identification: Identifying and confirming cases of infection through diagnostic testing.
2. Contact identification: Finding people who may have been in close contact with the infected case during their infectious period, which is the time when they can transmit the infection to others. Close contacts are usually defined as individuals who have had face-to-face contact with a confirmed case within a certain distance (often 6 feet or closer) and/or shared confined spaces for prolonged periods (usually more than 15 minutes).
3. Contact listing: Recording the identified contacts' information, including their names, addresses, phone numbers, and potentially other demographic data.
4. Risk assessment: Evaluating the level of risk associated with each contact based on factors such as the type of exposure, duration of contact, and the infectiousness of the case.
5. Notification: Informing contacts about their potential exposure to the infection and providing them with necessary health information, education, and guidance. This may include recommendations for self-quarantine, symptom monitoring, testing, and vaccination if available.
6. Follow-up: Monitoring and supporting contacts during their quarantine or isolation period, which typically lasts 14 days from the last exposure to the case. Public health professionals will check in with contacts regularly to assess their symptoms, provide additional guidance, and ensure they are adhering to the recommended infection prevention measures.
7. Data management: Documenting and reporting contact tracing activities for public health surveillance, evaluation, and future planning purposes.
Contact tracing is a critical component of infectious disease control and has been used effectively in managing various outbreaks, including tuberculosis, HIV/AIDS, Ebola, and more recently, COVID-19.
Surface properties in the context of medical science refer to the characteristics and features of the outermost layer or surface of a biological material or structure, such as cells, tissues, organs, or medical devices. These properties can include physical attributes like roughness, smoothness, hydrophobicity or hydrophilicity, and electrical conductivity, as well as chemical properties like charge, reactivity, and composition.
In the field of biomaterials science, understanding surface properties is crucial for designing medical implants, devices, and drug delivery systems that can interact safely and effectively with biological tissues and fluids. Surface modifications, such as coatings or chemical treatments, can be used to alter surface properties and enhance biocompatibility, improve lubricity, reduce fouling, or promote specific cellular responses like adhesion, proliferation, or differentiation.
Similarly, in the field of cell biology, understanding surface properties is essential for studying cell-cell interactions, cell signaling, and cell behavior. Cells can sense and respond to changes in their environment, including variations in surface properties, which can influence cell shape, motility, and function. Therefore, characterizing and manipulating surface properties can provide valuable insights into the mechanisms of cellular processes and offer new strategies for developing therapies and treatments for various diseases.
Cataract extraction is a surgical procedure that involves removing the cloudy lens (cataract) from the eye. This procedure is typically performed to restore vision impairment caused by cataracts and improve overall quality of life. There are two primary methods for cataract extraction:
1. Phacoemulsification: This is the most common method used today. It involves making a small incision in the front part of the eye (cornea), inserting an ultrasonic probe to break up the cloudy lens into tiny pieces, and then removing those pieces with suction. After removing the cataract, an artificial intraocular lens (IOL) is inserted to replace the natural lens and help focus light onto the retina.
2. Extracapsular Cataract Extraction: In this method, a larger incision is made on the side of the cornea, allowing the surgeon to remove the cloudy lens in one piece without breaking it up. The back part of the lens capsule is left intact to support the IOL. This technique is less common and typically reserved for more advanced cataracts or when phacoemulsification cannot be performed.
Recovery from cataract extraction usually involves using eye drops to prevent infection and inflammation, as well as protecting the eye with a shield or glasses during sleep for a few weeks after surgery. Most people experience improved vision within a few days to a week following the procedure.
Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:
1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.
Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.
Corneal transplantation, also known as keratoplasty, is a surgical procedure in which all or part of a damaged or diseased cornea is replaced with healthy corneal tissue from a deceased donor. The cornea is the clear, dome-shaped surface at the front of the eye that plays an important role in focusing vision. When it becomes cloudy or misshapen due to injury, infection, or inherited conditions, vision can become significantly impaired.
During the procedure, the surgeon carefully removes a circular section of the damaged cornea and replaces it with a similarly sized piece of donor tissue. The new cornea is then stitched into place using very fine sutures that are typically removed several months after surgery.
Corneal transplantation has a high success rate, with more than 90% of procedures resulting in improved vision. However, as with any surgical procedure, there are risks involved, including infection, rejection of the donor tissue, and bleeding. Regular follow-up care is essential to monitor for any signs of complications and ensure proper healing.
Amebiasis is defined as an infection caused by the protozoan parasite Entamoeba histolytica, which can affect the intestines and other organs. The infection can range from asymptomatic to symptomatic with various manifestations such as abdominal pain, diarrhea (which may be mild or severe), bloody stools, and fever. In some cases, it can lead to serious complications like liver abscess. Transmission of the parasite typically occurs through the ingestion of contaminated food or water.
Equipment design, in the medical context, refers to the process of creating and developing medical equipment and devices, such as surgical instruments, diagnostic machines, or assistive technologies. This process involves several stages, including:
1. Identifying user needs and requirements
2. Concept development and brainstorming
3. Prototyping and testing
4. Design for manufacturing and assembly
5. Safety and regulatory compliance
6. Verification and validation
7. Training and support
The goal of equipment design is to create safe, effective, and efficient medical devices that meet the needs of healthcare providers and patients while complying with relevant regulations and standards. The design process typically involves a multidisciplinary team of engineers, clinicians, designers, and researchers who work together to develop innovative solutions that improve patient care and outcomes.
Contact dermatitis is a type of inflammation of the skin that occurs when it comes into contact with a substance that the individual has developed an allergic reaction to or that causes irritation. It can be divided into two main types: allergic contact dermatitis and irritant contact dermatitis.
Allergic contact dermatitis is caused by an immune system response to a substance, known as an allergen, which the individual has become sensitized to. When the skin comes into contact with this allergen, it triggers an immune reaction that results in inflammation and characteristic symptoms such as redness, swelling, itching, and blistering. Common allergens include metals (such as nickel), rubber, medications, fragrances, and cosmetics.
Irritant contact dermatitis, on the other hand, is caused by direct damage to the skin from a substance that is inherently irritating or corrosive. This can occur after exposure to strong acids, alkalis, solvents, or even prolonged exposure to milder irritants like water or soap. Symptoms of irritant contact dermatitis include redness, pain, burning, and dryness at the site of contact.
The treatment for contact dermatitis typically involves avoiding further exposure to the allergen or irritant, as well as managing symptoms with topical corticosteroids, antihistamines, or other medications as needed. In some cases, patch testing may be performed to identify specific allergens that are causing the reaction.
Osteolysis is a medical term that refers to the loss or resorption of bone tissue. It's a process where the body's normal bone remodeling cycle is disrupted, leading to an imbalance between bone formation and bone breakdown. This results in the progressive deterioration and destruction of bone.
Osteolysis can occur due to various reasons such as chronic inflammation, mechanical stress, or certain medical conditions like rheumatoid arthritis, Paget's disease, or bone tumors. It can also be a side effect of some medications, such as those used in cancer treatment or for managing osteoporosis.
In severe cases, osteolysis can lead to weakened bones, increased risk of fractures, and deformities. Treatment typically aims to address the underlying cause and may include medication, surgery, or lifestyle changes.
Ophthalmodynamometry is a medical technique used to measure the amount of pressure or force required to flatten the cornea, which can help in the diagnosis and evaluation of various eye conditions, particularly glaucoma. It involves using a handheld device called an ophthalmodynamometer to apply gentle pressure to the eyelid while observing changes in the optic nerve head and retinal vessels through an ophthalmoscope. The test provides information about the resistance of the eyeball to external pressure, which can be useful in assessing the functioning of the eye's aqueous humor drainage system and identifying any abnormalities that may contribute to increased intraocular pressure (IOP).
The procedure typically involves several steps:
1. The patient is asked to look in different directions while the examiner observes the optic nerve head and retinal vessels through an ophthalmoscope.
2. The examiner then applies gentle pressure to the eyelid using the ophthalmodynamometer, gradually increasing the force until the cornea begins to flatten.
3. The amount of pressure required to achieve this is recorded as the ophthalmodynamometric value.
4. The examiner may repeat the process several times to ensure accurate and consistent results.
5. The results are then compared with normative data to determine whether the patient's IOP is within normal limits or if there are any signs of glaucoma or other eye conditions.
It is important to note that ophthalmodynamometry should only be performed by trained healthcare professionals, as improper technique can lead to inaccurate results and potential harm to the patient's eyes.
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Wearers24
- It's no surprise that Air Optix Night and Day Aqua are the contact lenses most recommended by eye doctors for contact lens wearers who sleep in their contacts. (contactlenses.co.uk)
- As Air Optix Night and Day Aqua have been designed and FDA approved for overnight wear, they are ideal for contact lens wearers who want to or need to sleep in their lenses, whether that's a firefighter on shout, a Doctor on call or a new parent deprived of sleep. (contactlenses.co.uk)
- Thankfully contact lens manufacturers have been trying to sort that issue out - so contact lens wearers don't have the problem of inserting and removing their contact lenses every day. (lensesonline.co.nz)
- On average, over five times as many epithelial microcysts than normal have been observed in long-term contact lens wearers. (wikipedia.org)
- Increased endothelial polymegethism is also found in long-term wearers of rigid gas permeable lenses as soon as one week after contact lens wear begins. (wikipedia.org)
- This change is indicated by significant increases in Max/Min cell size ratio in contact lens wearers. (wikipedia.org)
- these problems are sometimes correlated with astigmatism in contact lens wearers and are thought to be caused by hypoxia, surface molding, and chronic and mild trauma to the cornea from contact lens use. (wikipedia.org)
- Contact lens wearers can reduce their risk for contact lens-related infections by improving their hygiene behaviors, such as not sleeping in contact lenses unless prescribed and replacing their contact lenses as prescribed. (cdc.gov)
- 99% of contact lens wearers surveyed reported at least one behavior that puts them at risk for a contact lens-related eye infection ( 2 ). (cdc.gov)
- Continued efforts to educate contact lens wearers about prevention of contact lens-related eye infections are needed. (cdc.gov)
- Many eye care professionals and contact lens wearers feel that they offer the best of both worlds: They are convenient because no lens cleaning is required, and they are healthy because there is no day-to-day accumulation of lens deposits, and no overnight wear. (allaboutvision.com)
- The most common type of infection seen in contact wearers is ulcerative keratitis - a very painful infection that can erode the outer layers of the eye. (2020detroit.com)
- Researches have shown no unfavorable result to driving performance in adjusted monovision call lens wearers. (zhanmail.com)
- ACUVUE OASYS with HYDRACLEAR PLUS Technology contacts are 1-2 week lenses designed for contact lens wearers who experience eye dryness. (lens.com)
- Although a few contact lens wearers still have old-fashioned hard lenses, most outlets currently supply only two basic types-soft lenses and rigid gas-permeable lenses. (checkbook.org)
- 90% of wearers are likely to stay in Biofinity® as their lenses of choice. (lenstore.co.uk)
- Aquaclear is a monthly disposable contact lens from CooperVision, designed to bring contact lens wearers an advanced level of comfort in a monthly disposable lens. (lens.com)
- Fortunately, Aquaclear contacts can finally give contact lens wearers the best of both worlds. (lens.com)
- Cost-effective in the long run - Due to their extended lifespan, many wearers may find RGP lenses to be more economical over time when compared to regularly replaced soft lenses. (1800getlens.com)
- Ideal for special eye needs - RGP lenses are particularly beneficial for wearers with keratoconus and high levels of astigmatism than standard soft lenses. (1800getlens.com)
- This increased oxygen permeability means that wearers can safely use these silicone hydrogel lenses for extended periods. (1800getlens.com)
- The flexibility of soft lenses allows them to easily conform to the eye's shape, making them especially user-friendly for first-time wearers. (1800getlens.com)
- Spectacle wearers who would not normally wear lenses could now wear lenses for special occasions or during sports. (visiondirect.co.uk)
- These lenses are perfect for new lens wearers and experienced lens wearers alike. (feelgoodcontacts.com)
Astigmatism19
- AIR OPTIX for Astigmatism contacts can only be worn for extended wear (24 hours, including while you sleep) if directed by your eye doctor. (visioncenter.org)
- If you have astigmatism, there are extended wear contacts made just for you. (2020detroit.com)
- The American Academy of Ophthalmology says that hard lenses tend to work better in people with astigmatism, compared to soft versions. (2020detroit.com)
- Contact lens developers have created products for astigmatism, and some are made for extended wear. (2020detroit.com)
- If you have astigmatism and you'd like an extended wear product, it seems likely that your doctor can find something that would work for you. (2020detroit.com)
- A visibility tint can be added to different types of contacts, including toric (contacts for astigmatism) and multifocal (contacts for presbyopia) lenses. (lens.com)
- Their rigidity allows precise shaping, which also means they can be used to correct serious astigmatism that standard soft lenses are unable to correct (however, special soft toric lenses are available for this purpose). (checkbook.org)
- These lenses, which are available in both soft and hard varieties, can correct nearsightedness, farsightedness and astigmatism in combination with age-related loss of close-up vision (presbyopia). (haikhumble.com)
- Acuvue Oasys For Astigmatism is the only fortnightly lens developed for astigmats. (visiondirect.com.au)
- 1-2 weeks Disposable Extended Wear 7 Days Acuvue Oasys for Astigmatism 6 Pack contact lenses are disposable contact lenses meant to be worn for up to 2 weeks and you have the option to wear them as daily lenses or wear them day and night, without taking them out at night, for up to 7 days. (visiondirect.com.au)
- Versatility - Soft lenses come in a variety of designs to suit different vision needs, including spherical (for myopia or hyperopia), toric (for astigmatism), multifocal (for presbyopia), and even cosmetic (to change eye color). (1800getlens.com)
- May not be ideal for certain prescriptions - Soft lenses may not provide as crisp a vision as RGP lenses for high levels of astigmatism and other eye conditions. (1800getlens.com)
- Later, multifocal lenses and toric lenses for presbyopia and astigmatism came on the market. (visiondirect.co.uk)
- To correct astigmatism, the lens is designed specifically to the individual's correction needs. (howstuffworks.com)
- Whereas lenses used to correct myopia and hyperopia are spherical (the power correction is the same throughout the lens) astigmatism requires a special lens, called a toric lens . (howstuffworks.com)
- Ortho-k involves wearing special RGP contact lenses overnight to correct myopia and astigmatism. (wizzley.com)
- They don't offer lenses for astigmatism or any more serious vision disorders, but they make a good budget choice for anyone with mild astigmatism or basic near- or farsightedness. (innerbody.com)
- That means most people with astigmatism can't use their service, nor can those who require multifocal lenses. (innerbody.com)
- Toric contact lenses are shaped in a specific way to help correct astigmatism. (webeyecare.com)
Cornea33
- The special ingredient which makes the contact lenses so permeable is siloxane, not water, and this allows up to 6 times more oxygen to the cornea than standard soft contact lenses, making it a healthier option compared to lenses that let less oxygen through to your eye. (contactlenses.co.uk)
- As Air Optix Night and Day Aqua contain siloxane, not water, that allows up to 6 times more oxygen to reach the cornea than standard soft contact lenses, your Optometrist may recommend them for daily wear if they feel you need a higher level of oxygen to your cornea. (contactlenses.co.uk)
- When you wear regular daily or monthly disposable contact lens on your eye, this can reduces the amount of oxygen reaching the cornea. (contactlenses.co.uk)
- It sounds crazy, but the RGP lens gently reshapes the cornea of your eye while you sleep, allowing you to see clearly WITHOUT eye glasses or contact lenses during the day. (comfortable-contact-lens-secrets.com)
- You need to remove contact lenses as the lens actually blocks the flow of oxygen to your cornea so your eye needs a *rest* from the lens. (lensesonline.co.nz)
- Knowledge concerning the form and function of the cornea and the various types of contact lenses and their common complications is important to understanding this article. (wikipedia.org)
- The effects of extended contact lens wear on the cornea have been studied extensively and are well-documented. (wikipedia.org)
- When determining the effects of long-term contact lens use on the cornea, many studies do not differentiate between users of hard and soft contact lenses, while studies that have made this differentiation have found similar results. (wikipedia.org)
- This is probably because most contact lens-induced changes to the cornea are caused by hypoxia, which occurs as long as any physical barrier to the surface of the cornea is present. (wikipedia.org)
- Long-term use of soft hydrogel contact lenses has been shown to alter the following in the cornea: epithelial oxygen uptake, epithelial thickness, stromal thickness, and corneal endothelial morphology. (wikipedia.org)
- Greater corneal steepening was found in patients wearing soft contact lenses than in patients wearing rigid gas permeable contact lenses, suggesting that the latter may slow the progression of myopia by flattening the cornea. (wikipedia.org)
- Keratitis (inflammation of the cornea) can result from contact lens wear or other causes. (cdc.gov)
- These were a lot smaller than the original scleral lenses, as they rested just on the cornea instead of throughout every one of the noticeable eye surface area, as well as could be put on up to 16 hrs a day. (zhanmail.com)
- This feature, in turn, allows such lenses to be larger than old-fashioned hard lenses, which had to be small enough so that oxygen could pass around them to the cornea. (checkbook.org)
- While regular lenses should be removed each night for cleaning and to allow oxygen to freely reach the cornea, extended wear lenses can have longer intervals between removals. (checkbook.org)
- Support optimal eye health - The permeability of RGP lenses means they allow more oxygen to reach the cornea than standard soft lenses. (1800getlens.com)
- Some soft contact lenses are made of silicone hydrogels, which allow even greater levels of oxygen to reach the cornea. (1800getlens.com)
- Lower oxygen permeability - Standard hydrogel soft lenses may not allow as much oxygen to pass through to the cornea as some other lens types. (1800getlens.com)
- Contact lenses are thin transparent plastic discs that sit on the cornea. (howstuffworks.com)
- As the eye blinks, it provides lubrication to the cornea and helps flush away any impurities that may have become stuck to the lens. (howstuffworks.com)
- Sleeping with contacts can put stress on your cornea, limiting how much oxygen gets to your eye. (allaboutvision.com)
- Corneal neovascularization - An overgrowth of new blood vessels in your cornea , which triggers swelling - and can damage your eyes so much that you will never be able to be fitted for contacts again. (allaboutvision.com)
- The National Sleep Foundation reports that sleeping in contacts once in a while makes you seven times more likely to get an inflamed cornea. (allaboutvision.com)
- Contact lenses rest on the cornea . (improveyourvision.com)
- Since soft contact lenses cover the entire cornea an adequate amount of oxygen must pass through the contact to maintain the health of the eye. (improveyourvision.com)
- To determine if contact lenses are an option for a patient, the eye doctor will perform a complete eye exam and measure the curvature of the cornea . (improveyourvision.com)
- This number is usually between 8 and 10 and is important for the fixing of your prescription contacts because it will match up with the curvature of your cornea. (webeyecare.com)
- Poor contact lens hygiene may lead to infection of the cornea or persistent inflammation. (msdmanuals.com)
- There is too little moisture to keep the lens floating above the cornea. (msdmanuals.com)
- A small foreign particle (eg, soot, dust) becomes trapped between the lens and the cornea. (msdmanuals.com)
- which is a potentially vision-threatening infection of the cornea, is suspected when a contact lens wearer has intense eye pain (both foreign body sensation and ache), decreased vision, redness, photophobia, and tearing. (msdmanuals.com)
- Because the cornea becomes cone-shaped, patients cannot wear contact lenses for extended periods, and glasses can lose their effectiveness. (medscape.com)
- Donor tissue is inserted into the middle layer of the recipient eye through a tiny tube, which strengthens and flattens the cornea, making it easier to wear contact lenses. (medscape.com)
Discomfort6
- Use this time to ensure that your eyes are adjusting well to the contact lenses and that there is no discomfort or irritation. (sopicky.com)
- One patient discontinued lens wear because of discomfort without obvious clinical abnormalities. (eyehospital.nl)
- It might take up to a week to adjust to hard contact lenses, and they're more likely to slip off the center of your eye than are soft contact lenses - which might lead to discomfort and blurred vision. (haikhumble.com)
- Initial discomfort - RGP lenses can take some time for users to get used to. (1800getlens.com)
- Some customers report discomfort with regular use, and extended wearing can lead to severe complications. (innerbody.com)
- If you experience any pain or discomfort while wearing your contact lenses, even if it occurs after several weeks or months of use, you should discontinue use. (livedirtcheap.com)
Eyeglasses5
- We offer free basic 1.5 index lenses on all prescription eyeglasses. (smartbuyglasses.ie)
- The best part of wearing a contact lens is that you get an unhindered side view, which is not the case while wearing spectacles or eyeglasses. (inboundwriter.com)
- Contact lenses can boost your mood if you feel that eyeglasses stop you from looking your best or doing whatever you want. (inboundwriter.com)
- Contact lenses are closer to natural sight than eyeglasses. (howstuffworks.com)
- Neither rigid nor soft contact lenses offer the eyes the protection against blunt or sharp injury that eyeglasses do. (msdmanuals.com)
Corneal infection3
- Approximately 25% of the 1,075 MDRs described potentially modifiable factors that might have put the patient at risk for a contact lens-related corneal infection, such as sleeping in lenses or wearing lenses longer than for the prescribed period. (cdc.gov)
- 184 controls matched geographically and by contact lens tially blinding, corneal infection, was detected in the United use. (cdc.gov)
- Wearing contact lenses of any type increases the risk of corneal infection, simply because contact lenses reduce the amount of oxygen that reaches the corneas. (haikhumble.com)
Presbyopia3
- PureVision2 Multi-Focal For Presbyopia are visibility-tinted contact lenses. (visioncenter.org)
- The high burden of glaucoma, presbyopia, and other vision-related disorders is expected to propel the utility of smart contact lenses, thereby propelling the market growth. (researchandmarkets.com)
- Contact lenses are also used to correct presbyopia. (msdmanuals.com)
Permeable lenses3
- Gas permeable lenses. (2020detroit.com)
- Current versions of rigid gas-permeable lenses, introduced in 1979, allow oxygen to easily pass through them. (checkbook.org)
- Examples include corneal or epithelial disease (eg, dry eye ), superficial corneal injury or ocular injuries (eg, those due to foreign bodies ), exposure to ultraviolet light, and contact lens wear (eg, daily disposable soft lenses, extended-wear soft lenses, gas-permeable lenses, hard polymethylmethacrylate lenses). (medscape.com)
Optometrist14
- Always check with your Optometrist as to your suitability before wearing overnight contact lenses. (contactlenses.co.uk)
- Always check with your Optometrist before wearing any contact lenses continuously. (contactlenses.co.uk)
- Probably, you should always check with your Optometrist before wearing extended wear contact lenses, as you need regular check ups to monitor that enough oxygen is getting through to your eyes. (contactlenses.co.uk)
- If your optometrist approves, you can wear them for up to 30 days and nights. (sopicky.com)
- I was paying 4x as much for same lens from my optometrist. (justlenses.com)
- Please always check with your optometrist first before purchasing new contact lenses that haven't been prescribed. (lenstore.co.uk)
- American optometrist William Feinbloom developed a contact lens that combined glass and plastic. (visiondirect.co.uk)
- Only an optometrist or ophthalmologist should fit soft contact lenses. (improveyourvision.com)
- It is important to consult an optometrist before buying contact lenses. (livedirtcheap.com)
- Working with an optometrist can also provide an opportunity to 'test drive' or sample contacts. (livedirtcheap.com)
- Make sure you use caution and follow instructions from your optometrist when purchasing your contacts. (livedirtcheap.com)
- You also need to continue annual visits to your optometrist, even if the contacts improve your vision. (livedirtcheap.com)
- Speak with your optometrist to see if another brand or style of contact might work. (livedirtcheap.com)
- In overwear syndrome or any other condition in which pain does not quickly resolve when lenses are removed, an ophthalmologist or optometrist should be consulted before lenses are worn again. (msdmanuals.com)
Overnight wear8
- As these overnight lenses were then re-used after the 30 day period, the problems continued and as a result, for a time, the FDA banned all overnight wear contact lenses. (comfortable-contact-lens-secrets.com)
- These lenses are approved by the FDA for occasional overnight wear. (aclenscorp.com)
- Overnight wear of contact lenses has been shown to increase the risk of certain serious contact lens-related complications. (visioncenter.org)
- A daily wear lens is one that must be removed before sleeping, because it's not FDA approved for extended (overnight) wear . (allaboutvision.com)
- Unfortunately, overnight wear of contact lenses is not a good idea for everyone. (allaboutvision.com)
- As Aquaclear (Same as Biofinity) is approved for overnight wear (a full night's sleep), napping in them for a short period of time is not a problem. (lens.com)
- Unless your contacts have been approved for overnight wear, wearing contacts to sleep - especially if you do it frequently - can be very problematic. (allaboutvision.com)
- Although most lenses need to be removed at night, extended wear silicone-hydrogel lenses were approved for overnight wear by the FDA in 1999. (improveyourvision.com)
Complications4
- This can help reduce the risk of contact lens-related complications, such as corneal oxygen deficiency. (1800getlens.com)
- The risk of contact lens-related complications is also reduced with silicone hydrogel lenses. (1800getlens.com)
- The more often you sleep in your contacts and the longer you sleep in them, the more likely you may be to have these complications. (allaboutvision.com)
- None of the 19 patients studied experienced any complications after surgery, and all could wear contact lenses for extended periods. (medscape.com)
20231
- Hubble Contacts Review 2023: Good value or bad choice? (innerbody.com)
Bausch5
- Made using Bausch + Lomb's unique AerGel material, these contacts resist deposit buildup and stay moist all day. (lens.com)
- Bausch + Lomb ULTRA contacts keep eyes feeling fresh and healthy, thanks to MoistureSeal Technology. (lens.com)
- As such, Bausch + Lomb ULTRA contacts are a great option for heavy users of digital devices. (lens.com)
- Yes, all contact lenses, including Aquaclear (Same as Biofinity) ordered from Lens.com are FDA-approved, genuine lenses manufactured by top contact lens brands such as Bausch + Lomb and Alcon, and backed by a money-back guarantee. (lens.com)
- In the early 1970s, Bausch & Lomb released the first commercial soft contact lenses made of hydrogel lenses. (visiondirect.co.uk)
CooperVision4
- Biofinity monthly lenses use exclusive Aquaform® Technology developed by CooperVision. (visioncenter.org)
- Biofinity by CooperVision is a silicone hydrogel contact lens that provides all-month comfort and hydration. (sopicky.com)
- Biofinity® contact lenses are manufactured by CooperVision® , a world leader in contact lenses. (lenstore.co.uk)
- Aquaclear (Same as Biofinity) lenses are made from Silicone Hydrogel, using a specific formulation developed by CooperVision. (lens.com)
Multifocal contact3
- Bifocal or multifocal contact lenses. (haikhumble.com)
- Bifocal and multifocal contact lenses provide clear vision at all distances for those who have refractive errors and are experiencing age-related vision decline. (webeyecare.com)
- Rigid and soft bifocal and multifocal contact lenses can also be successful, but the fitting procedure is time-consuming because precise alignment is essential. (msdmanuals.com)
14.02
- Among these 1,075 reports, 925 (86.0%) were reported by a contact lens manufacturer and 150 (14.0%) by an eye care provider or patient. (cdc.gov)
- I would like to try a new lense that is dia 14.0 instead of the 14.2 i currently wear (changing from air optix to biofinity). (healthtap.com)
Wearer6
- While wearing contact lenses is a safe choice to glasses, they can come with issues that you might not expect- particularly if you are a brand-new call lens wearer. (zhanmail.com)
- The tint is just there so that the wearer can see the contacts when they are placed in lens solution. (lens.com)
- A good visibility tint also makes it easier for the wearer to find the lens if it is dropped. (lens.com)
- As a first-time contact lens wearer, everything from mastering the art of not poking your eye to choosing which type of lens to buy can be overwhelming. (allaboutvision.com)
- Although multi-purpose solutions advertise that they do not require the wearer to rub the contacts, they do recommend rinsing each side of the contact with the solution for 5 seconds before storing the lenses in their case. (improveyourvision.com)
- The wearer should put an ample amount of solution in the palm of one hand and gently rub the lens for about 10 seconds with the index finger of the other hand. (improveyourvision.com)
Corrective4
- He made molds of the human eye and then used these molds to design the front of corrective lenses. (visiondirect.co.uk)
- Your vision will be blurred when you remove corrective lenses including the biofinity torics. (healthtap.com)
- Corrective lenses are the most common treatment - either glasses or contact lenses. (guidedogs.org.uk)
- Contact lenses (contacts) are corrective lenses that are worn directly on the eye. (improveyourvision.com)
Professional's recommendations and the product itself2
- However, continuous wear will range according to a professional's recommendations and the product itself. (visioncenter.org)
- The duration of continuous wear will vary depending on your eye care professional's recommendations and the product itself. (sopicky.com)
Silicone hydrogel contact lens1
- Air Optix Night & Day Aqua is a silicone hydrogel contact lens that's FDA approved to be worn as a daily disposable contact lens or up to 30 consecutive nights. (contactlenses.co.uk)
Types of contact lenses2
- Extended wear contact lenses are one of the most popular types of contact lenses (also called continuous wear contact lenses). (sopicky.com)
- Start by understanding the pros and cons of common types of contact lenses - and the ground rules for preventing eye infections. (haikhumble.com)
Bifocal1
- Bifocal contacts have two prescriptions in a single lens, one for seeing up close and the other for seeing far away. (webeyecare.com)
Biofinity Toric3
- Biofinity Toric Contact Lenses (2 x 3 packs) are 30 day extended wear lenses. (eyecontacts.com.au)
- I've been wearing Biofinity Toric lenses for about 10 years with no difficulties. (justlenses.com)
- I have been wearing biofinity toric lenses for a month, i didn't wear them today and my vision is blurry. (healthtap.com)
Disposables are made1
- Like other contact lenses, disposables are made in both daily wear and extended wear versions. (checkbook.org)
Correct myopia and hyperopia1
- Either soft or rigid lenses are used to correct myopia and hyperopia. (msdmanuals.com)
Aquaform5
- The Aquaform® Technology contributes to the comfort and breathability of the lenses. (visioncenter.org)
- With Aquaform technology, these lenses deliver sufficient of oxygen to the eyes for optimal eye health. (sopicky.com)
- Month-long comfort - Aquaform® technology locks in moisture, keeping the lens clean and comfy throughout the entire month. (lenstore.co.uk)
- Thanks to the unique Aquaform technology, the lenses allow plenty of oxygen to reach your eyes for optimal eye health. (lenstore.co.uk)
- Thanks to technological advancements, Biofinity® lenses allow more oxygen to reach the eyes and the Aquaform technology ensures eyes are kept more hydrated, too. (lenstore.co.uk)
Glasses or contact lenses5
- Ortho-k lenses are NOT extended wear contact lenses, just contacts that are worn overnight to correct your vision so you eventually won't need to wear glasses or contact lenses again. (comfortable-contact-lens-secrets.com)
- Hyperopia can be corrected by wearing prescription glasses or contact lenses. (guidedogs.org.uk)
- Although wearing prescription glasses or contact lenses can correct your vision, your prescription can change over time and may need to be updated. (guidedogs.org.uk)
- If you already wear prescription glasses or contact lenses, you'll need to wear them. (guidedogs.org.uk)
- A prescription of 1.5 or more generally requires glasses or contact lenses. (guidedogs.org.uk)
Accumulate on the lenses2
- Even with extended wear lenses, dirt and debris accumulate on the lenses in a very short period of time. (hasenchat.uk)
- Naturally occurring mucous, protein and lipids can accumulate on the lenses in the form of deposits, which can irritate the eyes and can also act as a depot for bacteria. (improveyourvision.com)
Infection9
- These deposits make your contacts less comfortable than when they were new, and can also make your eyes more prone to infection. (allaboutvision.com)
- A brief or unintentional nap in your contacts can increase your risk of infection. (sopicky.com)
- Infection is a major concern associated with extended wear contacts. (2020detroit.com)
- The American Academy of Ophthalmology says the risk of this infection is 10 to 15 times higher in people who wear extended contacts, compared to those who wear daily versions. (2020detroit.com)
- Sleeping in your contacts increases your infection risk, doctors say. (2020detroit.com)
- After the doctor removes your cloudy lens and replaces it with a man-made model, drops can lower the chances of infection and help you heal. (webmd.com)
- According to the AAO , sleeping in contacts makes you six to eight times more likely to get an eye infection - and the risk is the same even if you only sleep in them every now and then. (allaboutvision.com)
- Sleeping in any lenses increases your risk for infection. (allaboutvision.com)
- The label may say they can be worn day and night, but wearing your lenses while sleeping can cause infection and eye damage. (alberta.ca)
Continuous wear contact3
- Yes, Air Optix Night and Day Aqua have been FDA approved to be worn as a continuous wear contact lens, that means you can wear the contacts up to 30 days and nights continuously. (contactlenses.co.uk)
- Extended wear contact lenses are also known as continuous wear contact lenses, they have been designed and approved for wearing on a continuous basis including overnight. (contactlenses.co.uk)
- They may also be referred to as continuous-wear contact lenses. (visioncenter.org)
Risk of corneal1
- Use of contact lenses increases risk of corneal ulcer. (msdmanuals.com)
Toric lens3
- Is blurry vision after not wearing my toric lens normal? (healthtap.com)
- Can toric lens cause vision to have yellow tint in treated eye? (healthtap.com)
- Acrysof toric lens put in R eye 10/14. (healthtap.com)
Hard lenses2
- Hybrid contact lenses might be an option if you have an irregular corneal curvature (keratoconus) or you have trouble wearing traditional hard lenses. (haikhumble.com)
- They are usually soft lenses, but there are also a few types of hard lenses designed for extended wear. (allaboutvision.com)
Daily disposable contact lenses3
- Modern daily disposable contact lenses allow enough oxygen through so your eyes stay healthy, however, if you sleep in contact lenses, because your eye lids are closed, the amount of available oxygen is severely reduced which can lead to corneal hypoxia and oedema, this is why it is always recommended to remove your contact lenses before sleeping unless of course they are extended wear contact lenses. (contactlenses.co.uk)
- Daily disposable contact lenses are single-use lenses that are removed and discarded at the end of each day, and a fresh pair of lenses is applied to the eyes the next morning. (allaboutvision.com)
- The other alternative is daily disposable contact lenses . (allaboutvision.com)
Continuously5
- One is to wear extended wear lenses continuously for several days, and then discard them when you remove them. (allaboutvision.com)
- The maximum time that any lens can be worn continuously is 30 days. (sopicky.com)
- Always check with your eye doctor before wearing any contacts continuously. (contactlensesplus.com)
- Extended wear disposables, designed to be worn continuously for one day or up to a month, depending on the brand, spare you the trouble of cleaning your lenses. (checkbook.org)
- These lenses may be worn continuously for up to 30 days and then replaced. (improveyourvision.com)
Vision33
- The makers Ciba Vision claim that they allow six times more oxygen through the lens than traditional soft lenses, which is why the FDA approve them for long term overnight use. (comfortable-contact-lens-secrets.com)
- It's basically a rigid gas permeable lens, designed to be worn overnight to actually correct your vision and in doing so, can avoid more expensive and certainly scary LASIK eye surgery. (comfortable-contact-lens-secrets.com)
- Johnson & Johnson offers two-week daily wear (or one-week extended wear) for those seeking comfort and clear vision. (visioncenter.org)
- Decreased corneal sensitivity, vision loss, and photophobia have also been observed in patients who have worn contact lenses for an extended period of time. (wikipedia.org)
- Long-term use of PMMA or thick hydrogel contact lenses have been found to cause increased eye irritability, photophobia, blurred vision, and persistent haloes. (wikipedia.org)
- Approximately 41 million persons in the United States wear contact lenses, a safe and effective form of vision correction if worn and cared for as directed. (cdc.gov)
- And while you might enjoy your coffee for half an hour, a fresh pair of lenses will provide comfort and good vision all day long. (allaboutvision.com)
- These lenses' smooth, wettable surface resists deposits, keeping your vision clear all day. (sopicky.com)
- In the past, extended wear lenses were made exclusively for people with uncomplicated vision issues. (2020detroit.com)
- In 1998, the first silicone hydrogel contact lenses were launched by Ciba Vision in Mexico. (zhanmail.com)
- LOVE the comfortable wear and hydration these lenses provide w/o sacrifice of clarity in vision wearing! (justlenses.com)
- With at least 2.2 billion people globally experiencing varying degrees of vision impairment, the prevalence of vision-related disorders could necessitate the adoption of smart contact lenses, consequently invigorating the market's growth trajectory. (researchandmarkets.com)
- Crisp & clear vision - The aspheric lens design increases your focus and improves vision clarity. (lenstore.co.uk)
- PureVision 2 HD are thin and comfortable lenses with unique High-Definition Optics that help to ensure sharpness of vision by reducing halos and glare. (lenstore.co.uk)
- In the world of vision correction, contact lenses have become an essential tool for many people. (1800getlens.com)
- Superior visual clarity - One of the standout features of RGP lenses is the high-quality vision they offer. (1800getlens.com)
- While these lenses were useful for correcting vision, they did cause problems. (visiondirect.co.uk)
- For people who need vision correction but don't want to wear glasses, contact lenses offer an easy, virtually invisible solution. (howstuffworks.com)
- Although nearly 36 million Americans wear contact lenses, not everyone wears them to correct vision problems. (howstuffworks.com)
- Celebrities use contact lenses to change the color of their eyes, athletes put them on to give them extra-sharp vision on the field, and others use them to make Halloween costumes more realistic. (howstuffworks.com)
- Contact lenses are shaped based on the vision problem to help the eye focus light directly on the retina. (howstuffworks.com)
- Next, we'll look at some vision problems and find out how contact lenses can correct them. (howstuffworks.com)
- Before we begin talking specifically about contacts, let's review how vision works and how lenses correct refractive vision problems. (howstuffworks.com)
- Toric contact lenses are made from the same materials as spherical lenses, but they have different angled curvatures to correct vision specifically for each individual. (howstuffworks.com)
- Presbyopes - people over age 40 who need help reading have plenty of options with contact lenses to improve their vision. (wizzley.com)
- You can adjust along a typical spectrum of power to ensure they can accurately correct your vision, but this only matters if your eye matches the contacts' base curve and diameter, which are set in stone. (innerbody.com)
- That is the goal of these lenses - to correct vision. (healthtap.com)
- A new daily disposable lens that doesn't just correct your vision, these incredible lenses allow you to see through things that would usually be opaque. (feelgoodcontacts.com)
- Many futuristic contact lenses have been in development over the years, including thermal vision, telescopic lenses, 3D printed lenses and even drug-delivery lenses for glaucoma patients. (feelgoodcontacts.com)
- Contact lenses allow people with imperfect vision to see clearly without wearing glasses. (livedirtcheap.com)
- This ensures healthy vision and comfort when wearing cheap contact lenses. (livedirtcheap.com)
- Contact lens prescriptions contain specific information to ensure that contact lenses are safe, comfortable, and provide optimum vision. (webeyecare.com)
- In this study, all participants had 20/400 vision with glasses before transplantation and could not wear contacts for extended periods of time. (medscape.com)
Increases4
- their number increases over time with extended contact lens wear. (wikipedia.org)
- And for many people, wearing contact lenses during sleep increases the risk of eye problems. (allaboutvision.com)
- It's still important to be cautious with overnight use, though, since it increases the risk of eye infections - even if the lenses have been approved for extended wear. (haikhumble.com)
- The risk increases about 15 times if contact lenses are worn overnight. (msdmanuals.com)
PureVision3
Soft44
- Some people have jobs or a lifestyle that makes wearing normal soft or RGP lenses very difficult if not impossible. (comfortable-contact-lens-secrets.com)
- One such lens is AIR OPTIX Night &Day Aqua, the first silicone hydrogel soft contact lens approved by the FDA that can be worn 24 hours a day for up to 30 days and nights, even while you sleep. (comfortable-contact-lens-secrets.com)
- Many people choose extended wear contacts to wear soft contact lenses overnight or for many days. (visioncenter.org)
- The high oxygen permeability also allows more oxygen flow than any other soft contact lens. (visioncenter.org)
- This type of soft lens wear also protects the eye from UV radiation with Class 2 UV Blocking properties. (visioncenter.org)
- In certain instances, hard contact lenses were shown to cause the same changes in corneal structure as soft contact lenses, though these changes were more dramatic because rigid lenses are capable of inflicting greater trauma on the eyes. (wikipedia.org)
- Among patients who have worn soft hydrogel contact lenses for over a year, significant reductions in epithelial oxygen uptake, epithelial thickness, and stromal thickness have been recorded, while an increase in endothelial polymegethism was found. (wikipedia.org)
- Furthermore, the reduction was more pronounced in patients wearing hard contact lenses than in patients wearing soft contact lenses. (wikipedia.org)
- This same effect was not found in patients who had worn soft contact lenses for an extended period of time. (wikipedia.org)
- They allow people to wear soft contact lenses overnight or for several days at a time. (sopicky.com)
- Polymers from which soft lenses are produced improved over the next 25 years, mostly in terms of enhancing oxygen leaks in the structure, by varying the active ingredients. (zhanmail.com)
- In 1972, British eye doctor Rishi Agarwal was the initial to suggest disposable soft get in touch with lenses. (zhanmail.com)
- Disadvantages of soft EWCL are lens precipitates, lens loss and failure to correct higher astigmatic errors. (eyehospital.nl)
- Soft lenses, introduced in 1971, are made of a gelatin-like substance with high water content. (checkbook.org)
- Their relatively long lifespans means they are likely to cost less in the long run than soft lenses. (checkbook.org)
- Both soft and rigid gas-permeable extended wear lenses are available. (checkbook.org)
- On May 26, 2007, the company voluntarily re- occurs primarily among users of soft contact lenses ( 5 ), called AMOCMP from domestic and international markets. (cdc.gov)
- Soft contact lenses are the most popular type of contact lens both in the United States and worldwide. (haikhumble.com)
- Soft contact lenses conform to the shape of your eye. (haikhumble.com)
- Daily wear soft contact lenses are typically the least expensive option. (haikhumble.com)
- You can wear extended wear soft contact lenses while you sleep, but they must be removed for cleaning and disinfecting at least once a week. (haikhumble.com)
- Disposable soft contact lenses are generally the most expensive option. (haikhumble.com)
- Hard contact lenses might be especially appealing if you've tried soft contact lenses and been unsatisfied with the results. (haikhumble.com)
- Hard contact lenses are often more breathable than are soft contact lenses, which reduces the risk of eye infections. (haikhumble.com)
- Hybrid contact lenses feature a hard (gas permeable) center surrounded by a soft outer ring. (haikhumble.com)
- Not only do these lenses allow plenty of oxygen to reach your eyes, but the lens material is naturally wet and stays moist, soft, and resistant to both dehydration and deposits. (lens.com)
- Their rigidity means they maintain their shape even when you blink, preventing the distortion that can sometimes happen with soft lenses. (1800getlens.com)
- Durability - With proper care, RGP lenses can last considerably longer than soft lenses, often up to a year or more. (1800getlens.com)
- They can initially feel more uncomfortable or foreign than soft lenses. (1800getlens.com)
- Soft contact lenses are primarily composed of gel-like, water-containing plastics known as hydrogels. (1800getlens.com)
- Immediate comfort - Soft lenses are more comfortable right from the start than RGP lenses. (1800getlens.com)
- Available in various modalities - Soft lenses are available in multiple replacement schedules, including daily, bi-weekly, and monthly options, catering to different lifestyles and preferences. (1800getlens.com)
- Can dry out - Soft lenses may become less comfortable in dry environments or during prolonged screen time. (1800getlens.com)
- High maintenance - With the exception of daily disposables, soft lenses require a consistent cleaning routine to prevent deposit buildup and potential eye infections. (1800getlens.com)
- Fragile - Due to their pliability, soft lenses can be more prone to tearing or damage, especially during insertion or removal. (1800getlens.com)
- Whiteout contact lenses are the most wanted and hot selling products all year round, because of how amazing, soft, and comfortable they are. (thefrisky.com)
- Soft contacts are made from a plastic called hydrogel and are about 35‰ to 80‰ water. (improveyourvision.com)
- What do soft contact lenses correct? (improveyourvision.com)
- Specialty soft contact lenses can be used to change eye color or to improve the appearance of an abnormal eye. (improveyourvision.com)
- Eye doctors may also use a soft contact lens as a temporary 'bandage' to relieve eye pain from a corneal injury or surgery. (improveyourvision.com)
- Although most patients can successfully wear soft contact lenses, they may not be appropriate for everyone. (improveyourvision.com)
- Today, most soft contact lenses are disposable and must be replaced at certain intervals depending on the manufacturer's and your eye doctor's recommendation. (improveyourvision.com)
- How Do I Clean and Disinfect Soft Contact Lenses? (improveyourvision.com)
- There are two types of soft contact lenses. (alberta.ca)
Infections8
- But in the past, extended wear contact lenses were deemed to be risky as eye infections, especially pink eye, often occurred after wearing contacts for 7 or more days at a time. (comfortable-contact-lens-secrets.com)
- During 2005-2015, a total of 1,075 MDRs describing contact lens-related corneal infections were reported to the FDA MDR database. (cdc.gov)
- To describe contact lens-related corneal infections reported to the FDA, 1,075 contact lens-related MDRs containing the terms "ulcer" or "keratitis" reported to FDA during 2005-2015 were analyzed. (cdc.gov)
- Bacteria can build up in the space between the contact and your eye, and that can lead to infections your doctor might struggle to treat. (2020detroit.com)
- Contact lenses can lead to bacterial or parasitic infections. (webmd.com)
- These lenses can damage your eyes and cause potentially serious eye infections. (haikhumble.com)
- Patients that have frequent eye infections, dry eye syndrome, ocular allergies, or certain other eye conditions may not be able to successfully wear contacts. (improveyourvision.com)
- Even though silicone-hydrogel lenses transmit up to 6 times more oxygen to the eye than traditional contacts, eye infections and inflammation are still possible when wearing these lenses overnight. (improveyourvision.com)
Type of lens2
- In the final analysis, when it comes to more traditional or extended wear lenses, it is important to consult with a qualified eye doctor to determine what type of lens will best suit your particular needs. (hasenchat.uk)
- Hubble offers one type of lens in one size. (innerbody.com)
Oxygen through the1
- Thanks to modern technology today contact lenses now allow around 6 times as much oxygen through the lens then contact lenses in the past. (lensesonline.co.nz)
Alcon1
- Alcon and Ciba Vision's Air Optix Night & Day Aqua contact lenses are monthly disposables. (sopicky.com)
Monthly disposable1
- These monthly disposable contacts also have a tapered edge design for maximum comfort. (lens.com)
Disinfection4
- Most hard contact lenses must be removed for cleaning and disinfection at night. (haikhumble.com)
- An eye care professional will demonstrate proper insertion, removal, and disinfection of the contact lenses. (improveyourvision.com)
- This International Standard specifies an antimicrobial efficacy end point methodology to determine compatibility of contact lens solutions, lens cases and hydrogel lenses for disinfection. (fda.gov)
- This provides a process for evaluating compatibility of solutions used for disinfection with contact lenses and lens cases using an antimicrobial efficacy end point. (fda.gov)