Refraction, Ocular: Refraction of LIGHT effected by the media of the EYE.Myopia: A refractive error in which rays of light entering the EYE parallel to the optic axis are brought to a focus in front of the RETINA when accommodation (ACCOMMODATION, OCULAR) is relaxed. This results from an overly curved CORNEA or from the eyeball being too long from front to back. It is also called nearsightedness.Hyperopia: A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus behind the retina, as a result of the eyeball being too short from front to back. It is also called farsightedness because the near point is more distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed)Refractive Errors: Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.Emmetropia: The condition of where images are correctly brought to a focus on the retina.Astigmatism: Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)Eyeglasses: A pair of ophthalmic lenses in a frame or mounting which is supported by the nose and ears. The purpose is to aid or improve vision. It does not include goggles or nonprescription sun glasses for which EYE PROTECTIVE DEVICES is available.Anisometropia: A condition of an inequality of refractive power of the two eyes.Photorefractive Keratectomy: A type of refractive surgery of the CORNEA to correct MYOPIA and ASTIGMATISM. An EXCIMER LASER is used directly on the surface of the EYE to remove some of the CORNEAL EPITHELIUM thus reshaping the anterior curvature of the cornea.Biometry: The use of statistical and mathematical methods to analyze biological observations and phenomena.Axial Length, Eye: The distance between the anterior and posterior poles of the eye, measured either by ULTRASONOGRAPHY or by partial coherence interferometry.Accommodation, Ocular: The dioptric adjustment of the EYE (to attain maximal sharpness of retinal imagery for an object of regard) referring to the ability, to the mechanism, or to the process. Ocular accommodation is the effecting of refractive changes by changes in the shape of the CRYSTALLINE LENS. Loosely, it refers to ocular adjustments for VISION, OCULAR at various distances. (Cline et al., Dictionary of Visual Science, 4th ed)Retinoscopy: An objective determination of the refractive state of the eye (NEARSIGHTEDNESS; FARSIGHTEDNESS; ASTIGMATISM). By using a RETINOSCOPE, the amount of correction and the power of lens needed can be determined.Visual Acuity: Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.Corneal Topography: The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.Keratomileusis, Laser In Situ: A surgical procedure to correct MYOPIA by CORNEAL STROMA subtraction. It involves the use of a microkeratome to make a lamellar dissection of the CORNEA creating a flap with intact CORNEAL EPITHELIUM. After the flap is lifted, the underlying midstroma is reshaped with an EXCIMER LASER and the flap is returned to its original position.Eye: The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.Lasers, Excimer: Gas lasers with excited dimers (i.e., excimers) as the active medium. The most commonly used are rare gas monohalides (e.g., argon fluoride, xenon chloride). Their principal emission wavelengths are in the ultraviolet range and depend on the monohalide used (e.g., 193 nm for ArF, 308 nm for Xe Cl). These lasers are operated in pulsed and Q-switched modes and used in photoablative decomposition involving actual removal of tissue. (UMDNS, 2005)Mydriatics: Agents that dilate the pupil. They may be either sympathomimetics or parasympatholytics.Cornea: The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)Refractive Surgical Procedures: Surgical procedures employed to correct REFRACTIVE ERRORS such as MYOPIA; HYPEROPIA; or ASTIGMATISM. These may involve altering the curvature of the CORNEA; removal or replacement of the CRYSTALLINE LENS; or modification of the SCLERA to change the axial length of the eye.Anterior Chamber: The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which presents through the pupil. (Cline et al., Dictionary of Visual Science, 4th ed, p109)Esotropia: A form of ocular misalignment characterized by an excessive convergence of the visual axes, resulting in a "cross-eye" appearance. An example of this condition occurs when paralysis of the lateral rectus muscle causes an abnormal inward deviation of one eye on attempted gaze.Myopia, Degenerative: Excessive axial myopia associated with complications (especially posterior staphyloma and CHOROIDAL NEOVASCULARIZATION) that can lead to BLINDNESS.Vision Tests: A series of tests used to assess various functions of the eyes.Pupil: The aperture in the iris through which light passes.SingaporeCyclopentolate: A parasympatholytic anticholinergic used solely to obtain mydriasis or cycloplegia.Presbyopia: The normal decreasing elasticity of the crystalline lens that leads to loss of accommodation.Keratotomy, Radial: A procedure to surgically correct REFRACTIVE ERRORS by cutting radial slits into the CORNEA to change its refractive properties.Amblyopia: A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition. Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.Lens Implantation, Intraocular: Insertion of an artificial lens to replace the natural CRYSTALLINE LENS after CATARACT EXTRACTION or to supplement the natural lens which is left in place.Optometry: The professional practice of primary eye and vision care that includes the measurement of visual refractive power and the correction of visual defects with lenses or glasses.Interferometry: Measurement of distances or movements by means of the phenomena caused by the interference of two rays of light (optical interferometry) or of sound (acoustic interferometry).Lenses, Intraocular: Artificial implanted lenses.Keratectomy, Subepithelial, Laser-Assisted: A surgical technique to correct REFRACTIVE ERRORS of the EYE, such as MYOPIA and ASTIGMATISM. In this method, a flap of CORNEAL EPITHELIUM is created by exposure of the area to dilute alcohol. The flap is lifted and then replaced after laser ablation of the subepithelial CORNEA.Corneal Wavefront Aberration: Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.Diagnostic Techniques, Ophthalmological: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.Strabismus: Misalignment of the visual axes of the eyes. In comitant strabismus the degree of ocular misalignment does not vary with the direction of gaze. In noncomitant strabismus the degree of misalignment varies depending on direction of gaze or which eye is fixating on the target. (Miller, Walsh & Hoyt's Clinical Neuro-Ophthalmology, 4th ed, p641)Refractometry: Measurement of the index of refraction (the ratio of the velocity of light or other radiation in the first of two media to its velocity in the second as it passes from one into the other).Lens, Crystalline: A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.Contact Lenses, Hydrophilic: Soft, supple contact lenses made of plastic polymers which interact readily with water molecules. Many types are available, including continuous and extended-wear versions, which are gas-permeable and easily sterilized.Keratoconus: A noninflammatory, usually bilateral protrusion of the cornea, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. The cause is unknown but hereditary factors may play a role. The -conus refers to the cone shape of the corneal protrusion. (From Dorland, 27th ed)Corneal Pachymetry: Measurement of the thickness of the CORNEA.Vision Screening: Application of tests and examinations to identify visual defects or vision disorders occurring in specific populations, as in school children, the elderly, etc. It is differentiated from VISION TESTS, which are given to evaluate/measure individual visual performance not related to a specific population.Tupaiidae: The only family of the order SCANDENTIA, variously included in the order Insectivora or in the order Primates, and often in the order Microscelidea, consisting of five genera. They are TUPAIA, Ananthana (Indian tree shrew), Dendrogale (small smooth-tailed tree shrew), Urogale (Mindanao tree shrew), and Ptilocercus (pen-tailed tree shrew). The tree shrews inhabit the forest areas of eastern Asia from India and southwestern China to Borneo and the Philippines.Lenses: Pieces of glass or other transparent materials used for magnification or increased visual acuity.Cataract: Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)Asian Continental Ancestry Group: Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.Phacoemulsification: A procedure for removal of the crystalline lens in cataract surgery in which an anterior capsulectomy is performed by means of a needle inserted through a small incision at the temporal limbus, allowing the lens contents to fall through the dilated pupil into the anterior chamber where they are broken up by the use of ultrasound and aspirated out of the eye through the incision. (Cline, et al., Dictionary of Visual Science, 4th ed & In Focus 1993;1(1):1)Vision, Binocular: The blending of separate images seen by each eye into one composite image.Body Weights and Measures: Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.Cataract Extraction: The removal of a cataractous CRYSTALLINE LENS from the eye.Tomography, Optical Coherence: An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.Corneal Diseases: Diseases of the cornea.Surgical Flaps: Tongues of skin and subcutaneous tissue, sometimes including muscle, cut away from the underlying parts but often still attached at one end. They retain their own microvasculature which is also transferred to the new site. They are often used in plastic surgery for filling a defect in a neighboring region.Keratoplasty, Penetrating: Partial or total replacement of all layers of a central portion of the cornea.New South Wales: A state in southeastern Australia. Its capital is Sydney. It was discovered by Captain Cook in 1770 and first settled at Botany Bay by marines and convicts in 1788. It was named by Captain Cook who thought its coastline resembled that of South Wales. (From Webster's New Geographical Dictionary, 1988, p840 & Room, Brewer's Dictionary of Names, 1992, p377)Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Vitreous Body: The transparent, semigelatinous substance that fills the cavity behind the CRYSTALLINE LENS of the EYE and in front of the RETINA. It is contained in a thin hyaloid membrane and forms about four fifths of the optic globe.Corneal Transplantation: Partial or total replacement of the CORNEA from one human or animal to another.Corneal Stroma: The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.Contact Lenses: Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)Age Distribution: The frequency of different ages or age groups in a given population. The distribution may refer to either how many or what proportion of the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Retinopathy of Prematurity: A bilateral retinopathy occurring in premature infants treated with excessively high concentrations of oxygen, characterized by vascular dilatation, proliferation, and tortuosity, edema, and retinal detachment, with ultimate conversion of the retina into a fibrous mass that can be seen as a dense retrolental membrane. Usually growth of the eye is arrested and may result in microophthalmia, and blindness may occur. (Dorland, 27th ed)Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Intraocular Pressure: The pressure of the fluids in the eye.Cross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Convergence, Ocular: The turning inward of the lines of sight toward each other.Adaptation, Ocular: The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)ReadingTreatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Postoperative Period: The period following a surgical operation.Contrast Sensitivity: The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.Microphthalmos: Congenital or developmental anomaly in which the eyeballs are abnormally small.Sex Distribution: The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine.

*Phakic intraocular lens

Rather it depends on central corneal power, anterior chamber depth (ACD) and patient refraction (preoperative spherical ... Although PIOLs for hyperopia are being investigated, there is less enthusiasm for these lenses because the anterior chamber ... The power of phakic lens is independent of the axial length of the eye. ... especially very high myopes and older patients. Endothelial cell loss especially for the anterior chamber PIOLs. A study ...
Looking for online definition of ocular refraction in the Medical Dictionary? ocular refraction explanation free. What is ocular refraction? Meaning of ocular refraction medical term. What does ocular refraction mean?
Purpose : To investigate the axial length and corneal radius of curvature (AL/CR) ratio in high versus low myopes and its relationship with myopia progression. Methods : Baseline AL/CR ratio of the right eyes of 310 high myopes (aged 7 to 16; myopia ≤ -6.00D) from the ZOC-BHVI High Myopia Registry (2012- 2013, Guangzhou, China) and 733 low myopes (aged 6 to 16; myopia -0.50D to -3.50D) from Vision CRC studies (2010-2014, Guangzhou, China) were calculated. Exclusion criteria were ocular disease, surgery or previous treatment for myopia. All participants underwent measurement of axial lengths (AL), corneal radii of curvature (CR) and cycloplegic objective refraction. Low myopes were followed 6 monthly for 12 months. Parental myopia was documented. General linear model was used to test the relationship between AL/CR ratio and spherical equivalent (SE) after ...
The effect of myopic defocus on myopia progression was assessed in a two-year prospective study on 94 myopes aged 9{14 years, randomly allocated to an undercorrected group or a fully corrected control group. The 47 experimental subjects were blurred by approximately +0.75 D (blurring VA to 6/12), while the controls were fully corrected. Undercorrection produced more rapid myopia progression and axial elongation (ANOVA, F(1,374)=14.32, p,0.01). Contrary to animal studies, myopic defocus speeds up myopia development in already myopic humans. Myopia could be caused by a failure to detect the direction of defocus rather than by a mechanism exhibiting a zero-point error ...
Myopia (nearsightedness) is an important public health problem, which entails substantial societal and personal costs. It is highly prevalent in our society and even more frequent in Asian countries; furthermore, its prevalence may be increasing over time. High myopia contributes to significant loss of vision and blindness. At present, the mechanisms involved in the etiology of myopia are unclear, and there is no way to prevent the condition. Current methods of correction require lifelong use of lenses or surgical treatment, which is expensive and may lead to complications. The rationale for this trial, the Correction of Myopia Evaluation Trial (COMET), arises from the convergence of research involving (1) the link between accommodation and myopia in children and (2) animal models of myopia showing the important role of the visual environment in eye growth. A contribution of this research is that blur is a critical component in the development of myopia. The primary aim of COMET, to evaluate the ...
The prevalence rate of myopia is rising rapidly in several Asian countries. A prevalence survey conducted in 1995 of 11178 school children in Taiwan were 12 percent for six year old and 84 percent for teenagers 16 o 18 years. Among them, twenty percent were high myopes. While in the United States and Europe the prevalence rate in older adults is 20% to 50%. The rate of progression of myopia is highest in young children, and the average age of stabilization of myopia is approximately 16 years.The onset of myopia may occur at a relatively young age, leading to higher risks of high myopia (myopia at least 6.0 diopters ) in adulthood. High myopia is associated with potentially blinding complications. Therefore, prevention of myopia progression is important in Taiwan, especially in young children.. There is some evidence that atropine eyedrops retard myopia progression in three randomized clinical trials. It is believed that atropine act on muscarinic receptor located in the sclera and through ...
Journal of Refractive Surgery | ABSTRACTBACKGROUND: Excimer laser photorefractive keratectomy tor the correction of myopia is presently under investigation in the United States by the Food and Drug Administration (FDA). The Phase 1 1 -B FDA study is being conducted on 75 normally sighted myopic eyes utilizing three currently available excimer lasers. This report presents the 1 -year results on 12 myopic eyes treated with the
Children are less likely to develop myopia when they are more often outside. Animal models show that bright laboratory lighting (15,000-25,000 lux) slows deprivation myopia (chick, tree shrew, monkey) and negative lens-induced myopia (chick, tree shrew). Long-term exposure for 3 months to bright light in the lab increases retinal dopamine production and release (chicks); and because a dopamine antagonist was found to cancel the effect of bright light on deprivation myopia (chicks), it was proposed that bright light might inhibit myopia development by stimulating dopamine release from the retina. But does bright light in the lab really reflect the natural conditions outside? Stone and colleagues1 have now compared deprivation myopia development in chicks in animal facilities and in real outdoor settings, with variable weather and illuminances. They found disappointingly small and temporary effects on deprivation myopia, and the effects on retinal dopamine were inconsistent-no effect of outdoor ...
The prevalence of myopia in developed countries in East and Southeast Asia has increased to more than 80% in children completing schooling, whereas that of high myopia has increased to 10%-20%. This poses significant challenges for correction of refractive errors and the management of pathological high myopia. Prevention is therefore an important priority. Myopia is etiologically heterogeneous, with a low level of myopia of clearly genetic origins that appears without exposure to risk factors. The big increases have occurred in school myopia, driven by increasing educational pressures in combination with limited amounts of time spent outdoors. The rise in prevalence of high myopia has an unusual pattern of development, with increases in prevalence first appearing at approximately age 11. This pattern suggests that the increasing prevalence of high myopia is because of progression of myopia in children who became myopic at approximately age 6 or 7 because age-specific progression rates typical of ...
Looking for online definition of nearsightedness in the Medical Dictionary? nearsightedness explanation free. What is nearsightedness? Meaning of nearsightedness medical term. What does nearsightedness mean?
Purpose: To compare refraction and ocular biometry in European Caucasian children aged 6-7 years and 12-13 years living in Sydney, Australia and Northern Ireland. Methods: All children had a comprehensive eye examination, including cycloplegic (cyclopentolate 1%) autorefraction (Sydney; Canon RK-F1, Northern Ireland; Shin-Nippon SRW-5000) and ocular biometry (IOLMaster, Carl Ziess). Hyperopia was defined as a right spherical equivalent refraction (SER) of ≥+2.00 dioptres (D), myopia as ≤-0.50D and astigmatism as a cylindrical error of ≥1.00D.Results: The mean SER was similar at age 6-7 yrs (p=0.9), however, at 12-13 yrs, children in Northern Ireland had a significantly less hyperopic mean SER (+0.66D) than children in Sydney (+0.83D, p=0.008). The prevalence of myopia, hyperopia and astigmatism was significantly greater in Northern Ireland than Sydney at both ages (all p ,0.03). The ...
Purpose: To investigate the association between serum vitamin D levels and myopia in young adults. Methods: A total of 946 individuals participating in the 20-year follow-up of the Western Australian Pregnancy Cohort (Raine) Study were included in this study. Ethnicity, parental myopia, and education status were ascertained by self-reported questionnaire. A comprehensive ophthalmic examination was performed, including postcycloplegic autorefraction and conjunctival UV autofluorescence photography. Serum 25-hydroxyvitamin D3 (25(OH)D3) concentrations were determined using mass spectrometry. The association between serum 25(OH)D3 concentrations and prevalent myopia was determined using multivariable logistic regression. Myopia was defined as mean spherical equivalent ≤ −0.5 diopters. Results: Of the 946 participants, 221 (23.4%) had myopia (n = 725 nonmyopic). Myopic subjects had lower serum 25(OH)D3 concentrations compared to nonmyopic participants (median ...
In another study, Atchison et al. 30 measured peripheral refraction out to 35° eccentricity in horizontal and vertical meridians of emmetropic and myopic subjects up to −12 D. Relative hyperopic and myopic shifts were reported in horizontal and vertical meridians, respectively, in the myopic group. Moreover, J 180 was found to increase negatively in horizontal, and positively in vertical meridians, relative to the fovea. In addition, Atchison et al. showed that the differences in peripheral refraction between myopic and emmetropic eyes are small when measured along the vertical meridian out to 30° eccentricity compared with those measured along the horizontal meridian. Figure 8 illustrates the comparison of our results with those in previous peripheral refraction studies on the horizontal and vertical meridians. Our data illustrate a relative hyperopic shift which was similar for all measured meridians for the myopic group, and a relatively constant ...
C H A P T E R 1 4 Excimer Laser Photorefractive Keratectomy for Keratoconus Arun C. Gulani, MD; Lee T. Nordan, MD; Noel Alpins, FRANZCO, FRCOphth, FACS; and George Stamatelatos, BSCOptom P atients with
Myopilux® lenses concept has been validated through two major clinical trials with approximately 600 children, with third party ethics committees approval.. The concept at the heart of Myopilux® Lite and Myopilux® Plus lenses was tested in the Correction of Myopia Evaluation Trial (COMET) study. The purpose was to evaluate the effect of progressive addition lenses (PALs) compared with single vision lenses (SVLs) on the progression of juvenile-onset myopia.[59] A total of 469 children were recruited in this study. The children were randomly assigned to either wearing single vision lenses or PALs with +2.00 D addition. The children were monitored for three years with six monthly follow-up visits. The primary outcome measure was progression of myopia, which was determined by auto-refraction after cycloplegia. The retention rate was extremely high with only 1% dropout rate. At the end of three years, the overall PALs group had a statistically significant reduction of 14% in myopia progression ...
Myopia ("near-sightedness") is a condition in which the optical system of the eye causes incoming light rays to focus in front of the retina, instead of focusing directly on the retinal surface. Various factors can cause this abnormal focus of light rays, including abnormalities of the lens or cornea, or by an eye that is abnormally long. Myopia is treated with glasses in younger children or, in some cases, contact lenses in older children and teenagers. Refractive surgery, such as Lasik, is generally reserved for adults except for certain limited studies in children less than 18 years of age. High myopia is generally defined as near-sightedness of -6.00 diopters or higher, and is often associated with a very long eye, termed a long "axial length." High myopia generally begins in early childhood, and continued growth of the eye often means that the corrective lens prescription required to allow proper focus may not stabilize until the early adult years. The prevalence of high myopia has been ...
The Visian® Implantable Collamer Lens (ICL) is a phakic intraocular lens used for the purpose of refractive surgery to correct myopia (nearsightedness). Unlike an intraocular lens that is used during cataract surgery, the Visian ICL does not replace the eyes natural lens. Instead, the ICL is placed between the iris and the natural lens to allow the ICL lens to work with your natural optical system and allow light to better focus on the retina.. Visian ICL does not permanently alter the structure of the eye, in comparison to corneal refractive surgery. Instead, the phakic intraocular lens is placed in the eyes posterior chamber, where it works with the natural lens to correct vision.. The phakic intraocular lens does not replace the natural lens, but instead supplements it like a prescription contact lens on the surface of the eye. This lens is sometimes referred to as an implantable contact lens.. The Visian ICL offers another option for treating myopia. Now, patients who are seeking the ...
This survey provides the first population-based cross-sectional data on the prevalence of myopia and high myopia and associated risk factors among the older adult in East China. The major finding was that myopia is common in East Chinese resident population with age ≥ 60 years. It indicated that 21.1% subjects had myopia, which was much lower than the rate (41.8%) among Japanese urban population with age ≥ 65 reported in the Tajimi study [18]. However, it was higher than the rate among rural Korean population in the same age group (13.2% in 60-69 years, 15.9% in 70-79 years, and 34.9% in 80+ years) [29]. The prevalence of myopia among older adult population in East China was lower than South China, and approximated North China. Different distribution of myopia in Chinese cities may suggest that environment and lifestyle may play an important role in myopia among older population, except reasons such as differences in ages of subjects included and the examination techniques used in different ...
Myopia, or near-sightedness, is an ocular refractive error of unfocused image quality in front of the retinal plane. Individuals with high-grade myopia (dioptric power greater than -6.00) are predisposed to ocular morbidities such as glaucoma, retinal detachment, and myopic maculopathy. Nonsyndromic, high-grade myopia is highly heritable, and to date multiple gene loci have been reported. We performed exome sequencing in 4 individuals from an 11-member family of European descent from the United States. Affected individuals had a mean dioptric spherical equivalent of -22.00 sphere. A premature stop codon mutation c.157C>T (p.Gln53*) cosegregating with disease was discovered within SCO2 that maps to chromosome 22q13.33. Subsequent analyses identified three additional mutations in three highly myopic unrelated individuals (c.341G>A, c.418G>A, and c.776C>T). To determine differential gene expression in a developmental mouse model, we induced myopia by applying a -15.00D lens ...
TY - JOUR. T1 - Laser vision correction in treating myopia. AU - Ehlke, Germano Leal. AU - Krueger, Ronald R.. PY - 2016/1/1. Y1 - 2016/1/1. N2 - Myopia is a generally benign refractive error with an increasing prevalence worldwide. It can be corrected temporarily with glasses and contact lenses and permanently with laser vision correction. The 2 main procedures currently being performed formyopia correction are photorefractive keratectomy and laser-assisted in situ keratomileusis. Each technique has its advantages, but they appear to yield similar visual outcomes 1 year after surgery. Laser vision correction for myopia was considered a paradigm shift because healthy eyes could now undergo a surgical procedure to permanently and safely correct the error by altering the center of the cornea, which was previously off limits because of the potential for loss of transparency. Customized ablation using wavefront aberrometry and its optimized profiles were created to correct higher-order aberrations ...
PURPOSE. To examine the association between the anthropometric measurements of height, weight, body mass index (BMI) and refraction and other ocular parameters in Singapore Chinese children. METHODS. In a cross-sectional study of 1449 Chinese school-children, aged 7 to 9 years, from three Singapore schools, height and weight were measured according to standard protocol, and BMI was calculated. Refractive error and corneal curvature measures were determined by autorefraction in eyes under cycloplegia. Axial length, vitreous chamber depth, lens thickness, and anterior chamber depth were measured using A-scan biometry ultrasonography. RESULTS. In comparison with the children with height in the first quartile for a given age and gender, the eyeball length in children in the fourth quartile was 0.46 mm longer, the vitreous chamber depth 0.46 mm deeper, the corneal radius of curvature 0.10 mm greater (i.e., flatter), refraction more negative by ...
Purpose: To compare the mean difference of visual acuity as measured by auto refraction and subjective refraction.. Study Design: Descriptive cross-sectional study.. Place and Duration of Study: Department of ophthalmology, Services hospital Lahore from November 2013 to April 2014.. Material and Methods: Using non-probability consecutive sampling 300 eyes of 300 patients fulfilling inclusion criteria were recruited through OPD registration slip. Demographic data including age and gender was recorded. Complete ophthalmic examination was performed. This included measurement of refractive error by auto-refraction as well as subjective refraction. Detailed anterior segment examination with slit lamp and dilated fundus examination with indirect ophthalmoscopy was performed. The collected data was analyzed by using software SPSS version 17.. Results: The mean age of patients was 34.71 ± 7.45 years. There were 156 (52%) males and 144 (48%) females. ...
Patients with myopia, hyperopia and astigmatism can now reduce or eliminate their dependence on contact lenses and eyeglasses through refractive surgery that includes radial keratotomy (RK), photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), laser thermal keratoplasty (LTK) and intrastromal corneal rings (ICR). Since the approval of the excimer laser in 1995, the popularity of RK has declined because of the superior outcomes from PRK and LASIK. In patients with low-to-moderate myopia, PRK produces stable and predictable results with an excellent safety profile. LASIK is also efficacious, predictable and safe, with the additional advantages of rapid vision recovery and minimal pain. LASIK has rapidly become the most widely performed refractive surgery, with high patient and surgeon satisfaction. Noncontact Holium: YAG LTK provides satisfactory correction in patients with low hyperopia. ICR offers patients with low myopia the potential advantage ...
The mean prediction error of the refractive outcome obtained in our study was 1.03 D (SD, 0.69 D) for SRK II group and 1.14 D (SD, 1.19 D) in Pediatric IOL Calculator group. This showed both groups ended more myopic than anticipated. However, there was no statistically significant different in the mean prediction error in both groups. Even though, the SRK II group had a lower prediction error of 0.11 D compared to the Pediatric IOL Calculator, we could not prove that SRK II is better than Pediatric IOL Calculator or vice versa. Our results showed that for the overall group, the prediction error is satisfactory and is comparable with errors demonstrated in adult group [21].. In our study, we further divided and analyzed the prediction error according to age group, axial lengths and keratometry. We divided the groups according to the age at time of surgery to less than 3 years old, and equal or older than 3 years old; axial length of less than 22 mm, and equal or more than 22 ...
Phakic Intraocular Lenses are an alternative to LASIK Surgery. At EyeCare 20/20 we offer advance eye-care treatments. Call us today to learn more.
The world renowned spectacle lens maker, Zeiss, has launched a new spectacle lens called MyoVision and it can slow the rate of Myopic progression for your child by as much as 30%.. The lens is a uniquely designed Single Vision lens, of different designs for the Right eye and the Left eye. It gives sharp vision in the centre but has a specially calculated degree of peripheral blur that lessens the stimulus for the eye to change shape. It is ground specially to your childs prescription.. It is based on research published by scientists from the Australian organisation "Vision Cooperative Research Centre" (Vision CRC) which partners up the University of Houston College of Optometry and the Brien Holden Vision Institute at the University of New South Wales.. Myopia affects over 1.6 billion people and is expected to reach 2.5 billion by 2020.. Successful basic research on the nature and cause of myopia has led to the discovery that the peripheral retinal image plays a major part in stimulating eye ...
We report the case of a high myopic patient who had been implanted with angle-supported phakic intraocular lenses (pIOL) in 1990 and who subsequently and gradually developed complications in both eyes including endothelial cell loss, chronic glaucoma, cataract, pupil ovalization and severe iris atrophy. The patient was impaired by photophobia, glare, halo, loss in visual acuity and concerned about the cosmetically deforming aspect of her eyes. Cataract surgery was performed after explantation of the pIOL followed by combined implantation of a standard IOL in the capsular bag and a Dr. Schmidt artificial iris in the sulcus. There were no intraoperative and postoperative complications except slight bilateral corneal oedema which resolved completely within 1 month after surgery. Uncorrected and corrected visual acuity improved progressively to reach 0.3 and 0.6 at the last follow-up visit (±1 year), respectively. The patient was very satisfied with the functional and aesthetical outcomes.
https://www.millioninsights.com/industry-reports/single-vision-lenses-market. With ordinary plastic lenses, a strong prescription can result in thicker, heavier glasses. In contrast, high0-index lens material will reduce thickness for greater comfort and a better appearance. Single Vision Lenses Market is classified, by applications into Myopia, Hyperpia, Astigmatism, presbyopia and combination of these conditions.. Single Vision Lenses Market is segmented, geographically into North America, Europe (Eastern Europe, Western Europe), Asia Pacific, Latin America, Middle East and Africa. North America accounted for the largest market share of the Single Vision Lenses Market and is expected to remain dominant over the forecast period. In North America, the U.S. is leading sub-segment and it is expected to remain dominant in forecast period due to increasing prevalence of ophthalmic cases. In the U.S. approximately 30 million people wear eye lens.. Europe is the second largest market for single vision ...
BACKGROUND: Early photorefractive keratectomy ablations were of limited diameter and depth to maintain the integrity of the globe and to minimise postoperative haze. This study evaluated the effects of deeper, larger diameter wounds on refractive stability and corneal haze, and investigated the effects of ablation profile on wound healing and visual performance. METHODS: One hundred patients undergoing -3.00D and -6.00D corrections were randomised to receive 5 mm, 6 mm, or multizone treatments. The multizone treatment was 6 mm in diameter, but only the depth of the 5 mm treatment. Outcome was measured by Snellen visual acuity, residual refractive error, objective techniques for haze and halos, pupil diameter, subjective night vision, and requirement for retreatment. RESULTS: Overall, the results of 6 mm treatments were superior to those of 5 mm and multizone treatments: they had a smaller hyperopic shift (p , 0.01), a more predictable (p , 0.001) and stable refractive outcome, less haze (p , ...
TY - JOUR. T1 - Effect of pupil dilation on biometric measurements and intraocular lens power calculations in schoolchildren. AU - Wang, Xiaogang. AU - Dong, Jing. AU - Tang, Maolong. AU - Wang, Xiaoliang. AU - Wang, Haitao. AU - Zhang, Suhua. PY - 2018/9/1. Y1 - 2018/9/1. N2 - Purpose To investigate the effect of pupil dilation on ocular biometric parameters and intraocular lens (IOL) power calculation in schoolchildren using the Lenstar LS 900. Methods One hundred forty eyes of 140 healthy schoolchildren were included in the analysis. Axial length (AL), central corneal thickness (CCT), aqueous depth (AD), anterior chamber depth (ACD), lens thickness (LT), flat keratometry (K), steep K, astigmatism, white-to-white (WTW), and iris/pupil barycenter distance were measured, before and after pupil dilation. Anterior segment length (ASL) was defined as the sum of ACD and LT, and lens position (LP) was defined as ACD plus half of the LT. The relative lens position (RLP) was defined as LP divided ...
To describe the results of refractive lens exchange (RLE) combined with simultaneous pars plana vitrectomy (PPV) in the management of severe myopia. This retrospective study comprised 14 eyes of eight patients who had RLE to treat myopia of −19.0±5.4 diopters (D). Phacoemulsification, posterior chamber intraocular lens (IOL) implantation, and standard three-port vitrectomy were performed. Mean postoperative follow-up time was 30 months (range 12-49). The postoperative best-corrected visual acuity (BCVA) was 0.68±0.23 compared to 0.37±0.24 preoperatively. There was no postoperative decrease in visual acuity in any eye. Mean postoperative spherical equivalent was −0.7 D (±1.6). At 30 months mean follow-up time, the spherical equivalents of nine eyes (64.3%) were within ±1 D of emmetropia. There was no significant change in astigmatism due to operative procedures. During the 30 months follow-up period three eyes (21.4%) required neodymium : ...
When to Vitamins and supplements may be able to help give you back some of your sparkle by making sure your body Some researchers have found that it is not as effective as vitamin D3 Sleep disorders may have reached epidemic proportions because of a common vitamin D deficiency. The Role of Thiamine Deficiency in Alcoholic Brain Disease Peter vitamin B 1 is an essential with WKS reverses many of the acute symptoms of the disease Because vitamin A and carotenoids play such a big role in cell and tissue growth The Skin Benefits of Vitamin C. High Myopia Soft Contact Lenses Colitis Floaters Eye Ulcerative dry eye is a This abnormal High Myopia Soft Contact Lenses High Myopia Soft Contact Lenses Colitis Floaters Eye Ulcerative Colitis Floaters Eye Ulcerative curvature of the cornea can cause double or blurred vision and most often affects children and young adults under 30 Information on edema and water retention swelling associated with the accumulation of fluid in spaces between the soft tissues of ...
An apparatus for determining the objective refraction of a patients eye includes a transparent window and a wavefront measurement device that determines aberrations in a return beam from the patients eye after the beam passes through a corrective test lens in the apparatus. The wavefront measurement device outputs an instant display representative of the quality of vision afforded the patient through the test lens. The display can be a representation of a Snellen chart, convoluted with the optical characteristics of the patients vision, an overall quality of vision scale or the optical contrast function, all based on the wavefront measurements of the patients eye. The examiner may use the display information to conduct a refraction examination and other vision tests without the subjective response from the patient.
Simultaneous intratunnel cross-linking with intrastromal corneal ring segment implantation versus simultaneous epithelium-off cross-linking with intrastromal corneal ring segment implantation for keratoconus management Mohamed Hosny, Moustafa Nour, Sarah Azzam, Mohsen Salem, Esraa El-Mayah Department of Ophthalmology, Cairo University, Giza, Egypt Purpose: The purpose of this study is to compare the efficacy of intratunnel cross-linking combined with intrastromal corneal ring segment (ICRS) implantation versus combined epithelium-off (epi-off) cross-linking and ICRS implantation for the management of keratoconus.Methods: Our study included 20 eyes of 12 patients with moderate-to-severe keratoconus. Group A included 10 eyes that underwent simultaneous ICRS implantation with intratunnel cross-linking. Group B included 10 eyes that underwent simultaneous ICRS implantation with epi-off cross-linking. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest sphere and
Eye conditions such as myopia (nearsightedness), hyperopia (farsightedness), and presbyopia are common conditions that affect the ability to see clearly. Common treatments, including eyeglasses, contact lenses, and surgery can help you see clearly again.
Advanced LASIK laser vision correction for nearsightedness, farsightedness and astigmatism. For those with a thin cornea, the PRK procedure corrects both low and high levels of nearsighted, farsighted and astigmatism. There are some differences between LASIK vs PRK, but both procedures provide the same vision correction outcomes that a patient deserves. LaHaye Total Eye Care has a specialized team of LASIK surgeons that personally care for your vision. Contact us today to schedule a LASIK or PRK consultation.
0065]The switching point is either a predetermined voltage value or a predetermined optical power value, which is used to determine whether the optical power value is retrieved from the first data table or the second data table. In the case where the switching point is a predetermined voltage value E-set, it is set equal to E-set1 in FIG. 3A (or E-set2 in FIG. 4A), and an optical power level is retrieved from the first data table (or the second data table). In this case, when the signal E-mon1 (or the signal E-mon2) is equal to or higher (or lower) than the voltage value E-set1 (or E-set2), the optical power value retrieved from the first data table (or the second data table) is used as a measured optical power value Pout. On the other hand, when the signal E-mon1 (or the signal E-mon2) is lower (or equal to or higher) than the voltage value E-set1 (or E-set2), the optical power value retrieved from the second data table (or the first data table) is used as a measured optical power value Pout. ...
Get information, facts, and pictures about Photorefractive keratectomy at Encyclopedia.com. Make research projects and school reports about Photorefractive keratectomy easy with credible articles from our FREE, online encyclopedia and dictionary.
Posts about laser vision correction written by customlasik. Dry eyes is the most common reported side effect of LASIK laser vision correction.Discover why VLEC now only offers all laser Lasik instead of Lasik. This is the technologically most advanced and predictable approach to laser vision correction.. Correct assessment and technical skill are critical aspects of laser eye. laser vision correction on. for LASIK. Also, Dr. Choi takes the time to guide you.Examples of a laser vision correction procedures include LASIK ...
An ocular hereditary disease preventable thanks to a DNA test. Congenital Stationary Night Blindness leads to a progressive vision loss. About 5% of briards are carriers of the genetic mutation responsible for the disease. A reliable DNA test can screen stud dogs and brood bitches, in order to adapt matings and avoid birth of affected puppies, and spread of the disease in the breed.. An incapacitating hereditary disease. Congenital stationary Night Blindness leads to a nervous system degeneration. First symptoms like balance disorders, and incapacity to coordinate movments are visible from birth. Puppies unable tostand or to move must be euthanised.. A fairly common disease. About 5% of briards in Europe are carrying of the mutation responsible of Congenital Stationary Night Blindness. A breeder can mate without noticing a male « carrier » and a female « carrier » and produce a litter containing affected puppies.. A dog « carrier » of the mutation will not develop the disease but transmits ...
Refractive error, also known as refraction error, is a problem with focusing light accurately onto the retina due to the shape of the eye. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain. Near-sightedness is due to the length of the eyeball being too long, far-sightedness the eyeball too short, astigmatism the cornea being the wrong shape, and presbyopia aging of the lens of the eye such that it cannot change shape sufficiently. Some refractive errors occur more often among those whose parents are affected. Diagnosis is by eye examination. Refractive errors are corrected with eyeglasses, contact lenses, or surgery. Eyeglasses are the easiest and safest method of correction. ...
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X-linked congenital stationary night blindness (CSNB) is a rare X-linked non-progressive retinal disorder. It has two forms, complete, also known as type-1 (CSNB1), and incomplete, also known as type-2 (CSNB2), depending on severity. In the complete form (CSNB1), there is no measurable rod cell response to light, whereas this response is measurable in the incomplete form. Patients with this disorder have difficulty adapting to low light situations due to impaired photoreceptor transmission. These patients also often have reduced visual acuity, myopia, nystagmus, and strabismus. CSNB1 is caused by mutations in the gene NYX, which encodes a protein involved in retinal synapse formation or synaptic transmission. CSNB2 is caused by mutations in the gene CACNA1F, which encodes a voltage-gated calcium channel CaV1.4. Not all Congenital Stationary Night Blindness (CSNB) are inherited in X-linked pattern. There are also dominant and recessive inheritance patterns for CSNB. The X-linked varieties of ...
AIM: To evaluate the clinical utility of automated refraction (AR) and keratometry (KR) compared with subjective or manifest refraction (MR) after cataract or refractive lens exchange surgery with implantation of Lentis Mplus X (Oculentis GmbH) refractive multifocal intraocular lens (IOL). METHODS: Eighty-six eyes implanted with the Lentis Mplus X multifocal IOL were included. MR was performed in all patients followed by three consecutive AR measurements using the Topcon KR-8000 autorefractor. Assessment of repeatability of consecutive AR before and after dilation with phenylephrine 10%, and comparison of the AR and KR with MR using vector analysis were performed at 3mo follow-up. RESULTS: Analysis showed excellent repeatability of the AR measurements. Linear regression of AR versus MR showed good correlation for sphere and spherical equivalent, whereas the correlation for astigmatism was low. The mean difference AR-MR was -1.28 0.29 ...
Mean spherical equivalent refraction treated was -6.56±2.74D (range: -2.25 to -13.00D). Median age was 33 years (range: 19 to 66 years). After SMILE, central corneal sensation dropped from 54-mm preoperatively to 32-mm (day one), rising to 40-mm (1 week), 44-mm (1 month), 49-mm (3 months), 54-mm (6 months), and 55-mm (12 months). Corneal sensation had reached baseline by 1, 3, 6, and 12 months in 62%, 76%, 89%, and 90% of eyes respectively. Twenty LASIK studies were identified; central corneal sensation dropped from 56-mm preoperatively to 9-mm (day one), rising to 15-mm (1 week), 22-mm (1 month), 33-mm (3 months), 44-mm (6 months), and 50-mm (12 months). Across the LASIK studies, mean spherical equivalent refraction treated was -4.30D and mean age was 34.2 years ...
PURPOSE: Proper refractive eye growth depends on several features of the visual image and requisite retinal pathways. In this study, we determined the contribution of rod pathways to normal refractive development and form deprivation (FD) myopia by testing Gnat1-/- mice, which lack functional rods due to a mutation in rod transducin-α. METHODS: Refractive development was measured in Gnat1-/- (n = 30-36) and wild-type (WT) mice (n = 5-9) from 4 to 12 weeks of age. FD was induced monocularly from 4 weeks of age using head-mounted diffuser goggles (Gnat1-/-, n = 9-10; WT, n = 7-8). Refractive state and ocular biometry were obtained weekly using a photorefractor, 1310 nm optical coherence tomography, and partial coherence interferometry. We measured retinal dopamine and its metabolite, DOPAC, using HPLC. RESULTS: During normal development, the refractions of WT mice started at 5.36 ± 0.68 diopters (D) and became more hyperopic before plateauing at 7.78 ± 0.64 D. In contrast, ...
Abstract: Purpose: To compare the accuracy of the Hoffer Q and Haigis formulae according to the anterior chamber depth (ACD) in cases of short axial length (AL).Design: Retrospective cross-sectional studyMethods: A total of 75 eyes from 75 patients with an AL of less than 22.0 mm implanted with an Acrysof IQ intraocular lens (IOL) were enrolled. The median absolute errors (MedAEs) predicted by the Hoffer Q and Haigis formulae were compared. The correlations between ACD and the predicted refractive error calculated using the two formulae were analyzed.Results: There were no significant differences in the MedAEs predicted by the Hoffer Q (Read more...) Full Story →. ...
DR MCQUAID: So the objectives of my talk today are hopefully that when were done here you will, first of all, be able to describe some ways in which to gain a childs trust, so that you can actually make a vision assessment, and perform some retinoscopy or refraction. Id like you to be able to name a few conditions which can be revealed by your first impression of seeing the child, and some very simple binocular assessments. You should be able to explain when were done here why retinoscopy is such an important, vital skill to have when it comes to dealing with children. And then you should also be able to mention a couple of ways to manage pediatric refractive error. So now the thing is - is Im not going to stand up here and teach you how to did retinoscopy or how to do refraction on a child or anybody else. What Im gonna do here is just give you some insight and some quick non-confrontational-type tests, and that sort of thing. Im going to assume that many, if not most of ...
V. Prevalence of refractive error in school children. 49± 2. Background: Uncorrected refractive error is the leading cause of eye problem and the second cause of blindness worldwide. . Only 10. 3. To assess the prevalence of refractive error and related visual impairment in school-aged children in the rural population of the Mahabubnagar district REFRACTIVE ERROR BLINDNESS OF REFRACTIVE ERRORS WORLD-WIDEStudies around the world indicate that refractive errors are common in all ages. 3 billion people worldwide have refractive errors out of The Refractive Error Study in Children (RESC) examined the prevalence of . 9% children were ever A study on the prevalence of refractive errors among school childern of 7-15 years The prevalence of uncorrected refractive error in urban and rural children hyperopia, myopia, presbyope, presbyopia, uncorrected refractive error In southern India, Nirmalan et al (5) found a prevalence of 55 per cent in people aged Dec 3, 2015 Introduction: Uncorrected refractive ...
The most common types of refractive errors are myopia, hyperopia, presbyopia, and astigmatism.. Myopia (nearsightedness) is a condition where objects up close appear clearly, while objects far away appear blurry. With myopia, light comes to focus in front of the retina instead of on the retina.. Hyperopia (farsightedness) is a common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience hyperopia differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant hyperopia, vision can be blurry for objects at any distance, near or far.. Astigmatism is a condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out.. Presbyopia is an age-related condition in which the ability to focus up ...
If you have thin corneas and were told you were not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), PRK (Photorefractive Keratectomy) may be a good option for you ...
If you have thin corneas and were told you were not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), PRK (Photorefractive Keratectomy) may be a good option for you ...
If you have thin corneas and were told you were not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), PRK (Photorefractive Keratectomy) may be a good option for you ...
If you have thin corneas and were told you were not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), PRK (Photorefractive Keratectomy) may be a good option for you ...
If you have thin corneas and were told you were not a candidate for laser-assisted in situ keratomileusis, or LASIK (a corneal refractive procedure that requires the creation of a partial-thickness flap before the cornea is sculpted with a laser), PRK (Photorefractive Keratectomy) may be a good option for you ...
Results Sphere changed from −1.77±6.57D (−11.00 to 7.00) preoperatively to 0.08±0.79D (−1.25 to 1.75) postoperatively (p=0.211), and cylinder changed from −2.95±1.71D (−7.00 to −0.75) to −1.40±1.13D (−3.25 to 0.00) (p=0.016). UDVA (logMAR) changed from 1.33±0.95 (0.40 to 2.77) to 0.32±0.38 (0.00 to 1.30) (p=0.008) and CDVA (logMAR) changed from 0.32±0.45 (0.01 to 1.77) to 0.20±0.36 (−0.03 to 1.30) (p=0.013). Efficacy and safety indexes were 1.38±0.58 and 1.17±0.66, respectively. Refraction and corneal topography were stable during the follow-up (9.10±5.54 months, 3-15). ...
A-scan ultrasound biometry, commonly referred to as an A-scan (short for Amplitude scan), is routine type of diagnostic test used in optometry or ophthalmology. The A-scan provides data on the length of the eye, which is a major determinant in common sight disorders. The most common use of the A-scan is to determine eye length for calculation of intraocular lens power. Briefly, the total refractive power of the emmetropic eye is approximately 60. Of this power, the cornea provides roughly 40 diopters, and the crystalline lens 20 diopters. When a cataract is removed, the lens is replaced by an artificial lens implant. By measuring both the length of the eye (A-scan) and the power of the cornea (keratometry), a simple formula can be used to calculate the power of the intraocular lens needed. There are several different formulas that can be used depending on the actual characteristics of the eye. All the information here is not valid for medical purposes. The other major use of the A-scan is to ...
An in-plane liquid gradient index (L-GRIN) microlens is designed for dynamically adjusting the beam focusing. The ethylene glycol solution (core liquid) withde-ionized (DI) water (cladding liquid) is co-injected into the lens chamber to form a gradient refractive index profile. The influences of the diffusion coefficient, mass fraction of ethylene glycol and flow rate of liquids on the refractive index profile of L-GRIN microlens are analyzed, and the finite element method and ray tracing method are used to simulate the convection-diffusion process and beam focusing process, which is helpful for the prediction of focusing effects and manipulation of the device. It is found that not only the focal length but the focal spot of the output beam can be adjusted by the diffusion coefficient, mass fraction and flow rate of liquids. The focal length of the microlens varies from 942 to 11 μm when the mass fraction of the ethylene glycol solution varies from 0.05 to 0.4, and the focal length changes from 127.1
Advanced computerized optical diagnostic equipment is revolutionizing eye care in the 21st century. Refraction is no exception. Traditionally, the refraction of the eye was given with spherical and cylindrical lens powers assumed to be valid across the entire pupil. However, using wavefront sensing, adaptive optics, and new treatment technologies, higher-order aberrations can be measured across the pupil and then modified or eliminated. Research has clearly shown that there are many applications involving these aberrations with diagnosis, treatment, and management of disorders, such as myopia, corneal disorders, presbyopia, cataract, and intraocular lens application and the dynamic changes in refractive state and retinal image quality produced by tear film thinning and accommodation. There are also many related questions that need to be answered regarding the natural stimulus for focusing, the patients perception of the aberrations and their correction, and ...
Purpose: To determine the testability of several vision and refraction tests in preschool-aged children. Design: Population-based study of Chinese preschool-aged children in Singapore. Methods: One thousand five hundred and forty-two Singaporean Chinese children aged 6 to 72 months were recruited through door-to-door screening of government-subsidized apartments in Singapore. Trained eye professionals administered all tests, including monocular logarithm of the minimum angle of resolution visual acuity with the Sheridan Gardiner chart, monocular Ishihara color testing (Richmond Products Inc, Albuquerque, New Mexico, USA), biometric measurements using IOLMaster (Carl Zeiss, Jena, Germany), and Randot stereoacuity (Stereo Optical Co, Chicago, Illinois, USA) for children 30 to younger than 72 months. Cycloplegic refraction and keratometry measurements also were determined using a table-mounted autorefractor (Canon Autorefractor RK-F1; Canon, Tokyo, Japan) in children 24 to ...
Digital Hand-held "Pocket" Sodium bicarbonate Refractometer PAL-64S, ATAGO - 23-5584 23-5584-58 Digital Hand-held Pocket Sodium bicarbonate Refractometer PAL-64S ATAGO 4464 P-R, Refractometers, ATAGO Refractometers, Food Additives, Ingredient Refractometers, ATAGO Handheld pocket refractometer for chemical product ingredient measurement of sodium bicarbonate 0.0 to 10.0%, with a temperature range between 10.0 to 40.0 degrees C Automatic temperature compensation (ATC) for immediate and accurate calibration readings, regardless of ambient temperature LED-illuminated digital display, with an external light interference (ELI) feature to alert of outside light interference Rectangular palm-sized shape (109 x 55 x 31mm), with prism housed in circular sample well Durable, acrylonitrile butadiene styrene (ABS) resin body, with Ingress-Protection (IP)-65 rating for protection against dust and water jets
Results Asymmetry of axial length, corneal power, vitreous chamber depth, anterior chamber depth, lens thickness and lens power were significantly more among participants who were anisometropic than those who were non-anisometropic. The correlation of anisometropia with axial length asymmetry was 0.735, 0.273 with corneal power, 0.183 with anterior chamber depth and 0.311 with lens power (p,0.001). In a multiple linear regression model, anisometropia was found to have significant associations with axial length asymmetry (standard coefficient (SC)=0.905), corneal power asymmetry (SC=0.350), lens power asymmetry (SC=0.454), nuclear opacity asymmetry (SC=0.074) and age (SC=0.28) (R2=85.1%). According to the linear regression model, corneal power had the strongest association with anisoastigmatism.. ...
Yam JC, Jiang Y, Tang SM, Law AKP, Chan JJ, Wong E, Ko ST, Young AL, Tham CC, Chen LJ, Pang CP.. PURPOSE: Low-concentration atropine is an emerging therapy for myopia progression, but its efficacy and optimal concentration remain uncertain. Our study aimed to evaluate the efficacy and safety of low-concentration atropine eye drops at 0.05%, 0.025%, and 0.01% compared with placebo over a 1-year period.. DESIGN: Randomized, placebo-controlled, double-masked trial.. PARTICIPANTS: A total of 438 children aged 4 to 12 years with myopia of at least -1.0 diopter (D) and astigmatism of -2.5 D or less.. METHODS: Participants were randomly assigned in a 1:1:1:1 ratio to receive 0.05%, 0.025%, and 0.01% atropine eye drops, or placebo eye drop, respectively, once nightly to both eyes for 1 year. Cycloplegic refraction, axial length (AL), accommodation amplitude, pupil diameter, and best-corrected visual acuity were measured at baseline, 2 weeks, 4 months, 8 months, and 12 months. Visual ...
The present application discloses a phakic intraocular lens (IOL) for the correction of visual disorders such as myopia, hyperopia, astigmatism and presbyopia. The lens is made from a biocompatible, elastomeric material such as silicone. The lens further includes one or more annular surfaces that protrude from the anterior surface of the lens or surrounds the lens such that when placed in the eye, it makes contact with the iris. As the iris dilates and constricts, the contact with the iris places a centering force on the implanted lens. The lens is not in contact with the natural lens of the eye and floats in the posterior chamber without insult or abrasion to surrounding tissue.
The spherical equivalent before surgery was −4.52 ± 1.96 diopters, falling to −0.22 ± 0.48 diopters after the procedure. Mean uncorrected distance visual acuity post-surgery (UDCVA) was −0.03 ± 0.11 LogMAR. 90.4% achieved UDCVA of at least 0.1 LogMAR (0.8 decimal). 88% showed no refraction one month after surgery and 96.5% had postoperative refraction of ≤0.50 D. Mean asphericity was −0.26 ± 0.19 before surgery and 0.19 ± 0.29 after surgery. Statistically significant differences were found for steep K, flat K, mean K, asphericity, spherical aberration and vertical coma (p < 0.005). On the other hand, no significant differences were found in the Root Mean Square (RMS) for higher order aberrations, horizontal coma or trefoil. Postoperative asphericity correlated strongly with 4th order spherical aberration and vertical coma. Six eyes developed intraoperative complications (confusion between the anterior and ...
0.50 diopter cycloplegic refractive change No evidence of optic-disc edema, nerve sheath distention, choroidal folds, globe flattening, scotoma or cotton-wool spots compared to baseline Class 1 Repeat OCT and visual acuity in 6 weeks Refractive changes ≥ 0.50 diopter cycloplegic refractive change and/or cotton-wool spot No evidence of optic-disc edema, nerve sheath distanton, choroidal folds, globe flattening or scotoma compared to baseline CSF opening pressure ≤ 25 cm H2O (if measured) Class 2 Repeat OCT, cycloplegic refraction, fundus examination and threshold visual field every 4 to 6 weeks × 6 months, repeat MRI in 6 months ≥ 0.50 diopter cycloplegic refractive changes or cotton-wool spot Choroidal folds and/or ONS distention and/or globe flattening and/or scotoma No evidence of optic-disc edema CSF opening pressure ≤ 25 cm H2O (if measured) Class 3 Repeat OCT, cycloplegic refraction, fundus examination and threshold visual field every 4 to 6 weeks × 6 months, repeat MRI ...
Combined vitreous and cataract surgeries in highly hyperopic eye Makoto Inoue1,2, Kei Shinoda3, Tomoko Matsuda-Yamamitsu2, Ronaldo Yuiti Sano1, Susumu Ishida2,41Kyorin Eye Center, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; 2Department of Ophthalmology, Keio University School of Medicine, Shinjuku, Tokyo, Japan; 3Department of Ophthalmology, Teikyo University School of Medicine, Itabashi, Tokyo, Japan; 4Department of Ophthalmology, Hokkaido University School of Medicine, Sapporo, Hokkaido, JapanAbstract: We report a case of a patient with a highly hyperopic eye who underwent cataract surgery combined with vitreous surgery to create a posterior vitreous detachment (PVD) to prevent choroidal neovascularization (CNV). A 78-year-old man noticed a decrease in his vision due to a cataract in his right eye. The patient had a severe visual loss in his left eye because of a CNV 2 years after a cataract surgery. His visual acuities were 20/30 OD and 20/600 OS, and funduscopic examination showed an
Optical ray tracing-guided myopic laser in situ keratomileusis: 1-year clinical outcomes Arthur B Cummings,1 Gabrielle E Kelly21Wellington Eye Clinic, Dublin, Ireland; 2School of Mathematical Sciences, University College Dublin, Dublin, IrelandPurpose: To compare the safety, efficacy, and predictability of laser in situ keratomileusis treatments at 1 year postprocedure using a novel geometric ray tracing algorithm with outcomes of treatments using wavefront-optimized, wavefront-guided, and topography-guided ablation profiles of an excimer laser (WaveLight GmbH, Erlangen, Germany; Alcon Laboratories, Fort Worth, TX, USA).Setting: Wellington Eye Clinic, Dublin, Ireland.Design: Retrospective comparative case series.Methods: Eyes having a preoperative myopic spherical equivalent refractive error >4.00 D and/or astigmatism between 2.00–6.00 D resulting in a spherical equivalent power greater than −4.00 D received laser in situ ...
Vol 9: Wnt Signaling in Form Deprivation Myopia of the Mice Retina.. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
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Aim: To determine the efficacy and safety of keratorefractive surgery in patients with accommodative and non-accommodative strabismus in a prospective study. Methods: Preoperative assessment included uncorrected (UCVA) and best corrected visual acuity (BCVA), manifest and cycloplegic refraction and orthoptic examination. LASIK, LASEK and Artisan phakic intraocular lens implantation were performed. All treated eyes had BCVA of at least 6/18 preoperatively. One year postoperatively, visual acuity, refractive error and ocular alignment were reassessed. Results: 28 patients (9 male, 19 female) of mean age 33.0±10.0 years (range 20 to 59). Esotropia was present in 16 patients; 9 fully accommodative, 3 partially accommodative and 4 non-accommodative. Twelve patients had exodeviations; 10 exotropia and 2 exophoria and history of strabismus surgery. Excellent visual and refractive outcomes were obtained postoperatively. There was no loss and one eye gained a line of BCVA. Fully accommodative ...
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The diagram on the right shows an example of refraction in water waves. Ripples travel from the left and pass over a shallower region inclined at an angle to the wavefront. The waves travel slower in the more shallow water, so the wavelength decreases and the wave bends at the boundary. The dotted line represents the normal to the boundary. The dashed line represents the original direction of the waves. This phenomenon explains why waves on a shoreline tend to strike the shore close to a perpendicular angle. As the waves travel from deep water into shallower water near the shore, they are refracted from their original direction of travel to an angle more normal to the shoreline.[3] Refraction is also responsible for rainbows and for the splitting of white light into a rainbow-spectrum as it passes through a glass prism. Glass has a higher refractive index than air. When a beam of white light passes from air into a material having an index of refraction that ...
LASIK which is customised according to the patients own optical (eye) aberrations is called custom-vue LASIK or wavefront guided LASIK.. What are optical aberration?. Optical aberration are the natural defects in the refractive state/mechanism of the eye due to which the patient cannot focus and see objects clearly. There are different types of optical aberrations. Lower order aberrations are rectified in a normal LASIK but for significant higher order aberrations, wavefront guided LASIK is required.. What is done in custom-vue LASIK or wavefront guided LASIK?. Firstly, the patients eyes are scanned to find out its optical aberrations. Then, this data is fed into the LASIK machine, where the computer generates the laser for rectifying these errors, according to the individual optical aberrations, during LASIK surgery.. Do all cases require custom-vue LASIK or wavefront guided LASIK?. This depends upon the type of optical aberrations present in ones eye. For lower order aberrations normal ...
DISCUSSION. The main aim of modern refractive surgery is an improvement in the quality of life of patients with a refractive error connected to a high degree of dependence on glasses correction or contact lenses. With the arrival of the excimer laser more than 25 years ago, photorefractive procedures on the cornea became far more precise with regard to the predictability of the postoperative refractive result, as well as safer in comparison with the previously used technique of radial keratectomy and ketatomileusis. Despite the fact that it is possible to resolve a large number of refractive errors by means of modification of the shape of the cornea, for a section of patients this procedure is not suitable. Thanks to new and better-quality materials of P IOL, visco-elastic material, surgical micro-techniques and possibilities of instrument display, at the end of the 1980s and beginning of the 1990s the idea of correcting higher refractive errors by means of implantation of a P IOL reappeared (5, ...
Purpose: The aim was to assess the visual impact of ocular wavefront aberrations, corneal thickness, and corneal light scatter prospectively after performing a Descemet stripping automated endothelial keratoplasty (DSAEK) in humans. Methods: Data were obtained prospectively from 20 eyes preoperatively and at 1, 3, 6, and 12 months post-DSAEK. At each visit, the best spectacle-corrected visual acuity and visual acuity with glare (brightness acuity testing) were recorded, and ocular wavefront measurements and corneal optical coherence tomography (OCT) were performed. The magnitude and the sign of individual Zernike terms [higher-order aberrations (HOAs)] were determined. Epithelial, host stromal, donor stromal, and total corneal thicknesses were quantified. The brightness and intensity profiles of OCT images were generated to quantify light scatter in the whole cornea, subepithelial region, anterior and posterior host stroma, interface, and donor stroma. Results: The mean best spectacle-corrected visual
Glycerol is a clear, colorless, and sweet-tasting, viscous liquid also frequently referred to as glycerin or glycerine. It is also less commonly known as 1,2,3-propanetriol, 1,2,3-trihydroxypropane, or glycol alcohol. Glycerol belongs to the alcohol family in organic compounds and contains three hydroxyl groups (-OH). The chemical formula of glycerol is C3H8O3 and the molecular formula is HOCH2CHOHCH2OH. Glycerol is a common substance found in soap, cosmetics, creams, and foods as well as being used in chemical studies and experiments.. Refraction is the change in angle of light when moving from one medium into another. The index of refraction, n, can be determined by c/v where c is the approximate speed of light, 3 × 108 m/s, and v is the phase velocity, or the speed inside the medium. However, the refractive index is also defined as a constant that is the ratio of the sine of the angle of incidence to the sine of the angle of refraction. This application ...
Astigmatism is a common condition in which the cornea of the eye has a shape similar to that of a football, rather than a normal corneal shape resembling a baseball. Because the cornea is oddly shaped, light bends unequally as it enters the eye, causing vision distortion or blurriness.. Many who suffer from astigmatism do not know that it can often be corrected with LASIK eye surgery. Laser-assisted in situ keratomileusis (LASIK) is a popular form of laser eye surgery that reshapes the inner layer of the cornea to correct myopia, hyperopia and astigmatism. LASIK eye surgery has proven to be an effective treatment for many patients with mild or moderate astigmatism. LASIK is also a convenient option for many other people, even if they dont have astigmatism.. LASIK for astigmatism is accomplished by smoothing out the irregularities of the cornea at the precise points of the astigmatism, therefore allowing light to focus correctly on the retina. During the LASIK procedure in Buffalo, pulses of ...
The AOAs stance on these companies prompts the question: Does online refraction actually threaten optometrys model? Consider the lesson of Google Maps.11 Google managed to topple the navigation device market (remember your Tom Tom GPS?) on four main selling points: price, quality, convenience and personalization. Improving on all four of these aspects disrupted the personal navigation device market forever.10 It may be worth discussing with patients whether online refraction companies can beat optometry in any of these selling points. Price. No optometrist would provide a refraction separate from a comprehensive eye exam, explains John Rumpakis, OD, CEO of Practice Resource Management, Inc. However, since thats what these companies are doing, a hypothetical price-by-price comparison may be an appropriate point to discuss with patients. Opternative offers a glasses or contacts prescription for $40 ($60 for both). Although optometry offers a comprehensive exam ...
D5777 - 00(2011)e1 Standard Guide for Using the Seismic Refraction Method for Subsurface Investigation , Archeological investigations, Field testing--soil, Geological investigations, Geophysical investigations/geophysics, Hydrogeologic models/investigations, Mineral exploration, Petroleum exploration, Refraction, Seismic refraction, Subsurface investigation--soil/rock, Surface analysis--soil/rock/related materials,
Refractive errors occur when there is a mismatch between the axial length of an eye and its refractive power, which is produced by the cornea, lens and anterior chamber depth. When the axial length matches the optical power, without accommodation, the images of distant objects are focused sharply on the photoreceptors and the eye is emmetropic. However, if the eyes axial length becomes longer than the focal plane, the images are focused in front of the retina and the eye is myopic. Juvenile-onset myopia affects a significant fraction of the worlds population [1]. As shown by studies in animal models (fish, chicks, monkeys, guinea pigs, tree shrews, and other species) [2-6] and humans [7], an emmetropization mechanism uses visual signals during the early postnatal period to guide the axial elongation rate (primarily the vitreous chamber depth) so that the retina comes to be located close to the focal plane, typically producing eyes that are ...
Parents of children with anisometropia ≥ 2.00D were also more likely to have developmental concerns (OR= 2.61; 95% CI: 1.07 - 6.34).Table 5Association of significant refractive errors with parental report of Refractive Errors Physicians Locations Was this helpful? The odds of parental concerns about development significantly increased in children older than 36 months with hyperopia ≥ 3.00D, astigmatism ≥ 1.50D, or anisometropia ≥ 2.00D.ConclusionsParental concerns about general developmental problems Normal Refractive Error In Children It is possible to have astigmatism in combination with myopia or hyperopia.. PreviousNormal Vision Development in Babies and ChildrenNextChildhood Eye Diseases and Conditions Leer en Español: Errores Refractivos en los Niños Due to the potential consequences of uncorrected refractive errors, children whose parents have expressed concerns regarding development should be referred for an eye examination with cycloplegic ...
Myopia is a significant public health problem that affects at least 34% of children in the United States and a much higher percentage in Asia. It is a predisposing factor for retinal detachment, myopic retinopathy, and glaucoma, thus contributing to loss of vision and blindness. As might be expected for such a prevalent condition, treatment costs are high. If interventions to retard myopia progression are successful, sight-threatening complications might be avoided and costs should be reduced.. The study has been designed as a simple trial that, other than the type of lenses being determined through the randomization process and the addition of accommodation testing using an autorefractor, largely approximates standard clinical practice.. Screening consists of non-cycloplegic procedures of subjective refraction, testing of oculomotor alignment, and testing of accommodative response using the Grand Seiko autorefractor.. Patients who appear to be eligible for the randomized trial will be ...
Myopia is a significant public health problem that affects at least 34% of children in the United States and a much higher percentage in Asia. It is a predisposing factor for retinal detachment, myopic retinopathy, and glaucoma, thus contributing to loss of vision and blindness. As might be expected for such a prevalent condition, treatment costs are high. If interventions to retard myopia progression are successful, sight-threatening complications might be avoided and costs should be reduced.. The study has been designed as a simple trial that, other than the type of lenses being determined through the randomization process and the addition of accommodation testing using an autorefractor, largely approximates standard clinical practice.. Screening consists of non-cycloplegic procedures of subjective refraction, testing of oculomotor alignment, and testing of accommodative response using the Grand Seiko autorefractor.. Patients who appear to be eligible for the randomized trial will be ...
Intraocular lens (IOL) is a lens implanted in the eye used to treat cataracts or myopia. The most common type of IOL is the pseudophakic IOL. These are implanted during cataract surgery, after the cloudy crystalline lens (otherwise known as a cataract) has been removed. The pseudophakic IOL replaces the original crystalline lens, and provides the light focusing function originally undertaken by the crystalline lens. The second type of IOL, more commonly known as a phakic intraocular lens (PIOL), is a lens which is placed over the existing natural lens, and is used in refractive surgery to change the eyes optical power as a treatment for myopia, or nearsightedness. IOLs usually consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place within the capsular bag inside the eye. IOLs were conventionally made of an inflexible material (PMMA), although this has largely been superseded by the use of flexible materials.[citation needed] Most IOLs fitted today are ...
Corneal topography provides us with the most detailed possible information about the curvature of the eye and potential eyesight and eye disease issues.. Using a very sophisticated computer and software, thousands of measurements are taken and analyzed in just seconds. The computer generates a colour map from the data. This information is useful to evaluate and correct astigmatism, monitor corneal disease, and detect irregularities in the corneal shape.. Corneal topography is interpreted much like other topography maps. The cool shades of blue and green represent flatter areas of the cornea, while the warmer shades of orange and red and represent steeper areas. This corneal map allows the optometrist to formulate a "3-D" perspective of the corneas shape. Measuring astigmatism is important for fitting contact lenses, and calculating lens power.. Corneal topography is a process for mapping the surface curvature of the cornea, similar to making a contour map of land. The cornea is a clear membrane ...
Refraction. Computer artwork showing the refraction of light beams through a biconcave lens. Light changes direction, or is refracted, when it meets a different transparent medium such as a lens. A biconcave lens causes light beams to diverge. It is used to correct myopia (short- sightedness), a condition in which light is focused before it reaches the retina. - Stock Image A205/0081
We studied the age dependence of the relative contributions of the aberrations of the cornea and the internal ocular surfaces to the total aberrations of the eye. We measured the wave-front aberration of the eye with a Hartmann-Shack sensor and the aberrations of the anterior corneal surface from the elevation data provided by a corneal topography system. The aberrations of the internal surfaces were obtained by direct subtraction of the ocular and corneal wave-front data. Measurements were obtained for normal healthy subjects with ages ranging from 20 to 70 years. The magnitude of the RMS wave-front aberration (excluding defocus and astigmatism) of the eye increases more than threefold within the age range considered. However, the aberrations of the anterior corneal surface increase only slightly with age. In most of the younger subjects, total ocular aberrations are lower than corneal aberrations, while in the older subjects the reverse condition occurs. Astigmatism, coma, and spherical ...
A process is disclosed for fabricating an improved antireflection coating on a substrate. A layer of dielectric material having a first thickness and a first index of refraction are formed overlying a substrate. The dielectric material is implanted with hydrogen to form an implanted surface region having a thickness less than the thickness of the entire layer of dielectric material. The hydrogen reduces the index of refraction of the implanted region to a value less than the index of refraction of the initial layer. The structure overlying the substrate thus includes two integral layers having different indices of refraction with the lower index of refraction, as desired, at the surface of the dielectric material. The process can be extended by further implantation to provide an increased number of distinct layers of differing index or to provide a continuum of regions of varying index of refraction.
Myopic shift occurs most rapidly in the first 1.5 years of life after IOL implantation in infancy, reported David R. Weakley, Jr., MD, and fellow researchers. They were focused on a myopic shift at age 5 after cataract surgery with IOL implantation for infants in the Infant Aphakia Treatment Study. Researchers performed refractions at 1 month and at every 3 months until age 4, and then at 4.25, 4.5, and 5 years of age. Of 43 eyes that were analyzed, the mean rate of myopic direction change from 1 month after surgery to age 1.5 years was 0.35 D; after age 1.5 years, the mean rate of myopic direction change was 0.97 D per year. In children who had surgery at age 1 month and were age 5 at the time of the study, the mean refractive change was 8.97 D. The mean refractive error at age 5 was -2.53 D. "If the goal is emmetropia at age 5 years, then the immediate postoperative hypermetropic targets should be +10.5 D at 4 to 6 weeks and +8.50 D from 7 weeks to 6 months," the researchers concluded. ...
Based on a simple eye model system, a high resolution adaptive optics retina imaging system was built to demonstrate the availability of using liquid crystal devices as a wave-front corrector for both low and high order aberrations. Myopia glass was used to introduce large low order aberrations. A fiber bundle was used to simulate the retina. After correction, its image at different diopters became very clear. We can get a root mean square(RMS) correction precision of lower than 0.049λ (λ =0.63μm) for over to 10 diopters and the modulation transfer function (MTF) retains 51lp/mm, which is nearly the diffraction limited resolution for a 2.7mm pupil diameter. The closed loop bandwidth was nearly 4 Hz, which is capable to track most of the aberration dynamics in a real eye.. ©2007 Optical Society of America. Full Article , PDF Article ...
These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: They are myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common ...
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Lasik Eye Surgery can sometimes be appropriate for people with Presbyopia, the age related near vision focusing problem. Laser Eye Surgery and in particular LASIK surgery, is a safe effective and predictable method of correcting nearsightedness, farsightedness and astigmatism. These common vision problems occur because the refractive power of your eyes is not accurate so as to allow light to focus at a precise point on your retina. Another type of common vision problem that is due to a deficiency in the actual focusing mechanism within your eyes is called presbyopia.. Presbyopia, which literally means old eyes, is a normal and expected consequence of the aging process. The crystalline lens within your eyes is composed of proteins. These proteins are soft and flexible when you are younger. Beginning as you approach your 40s presbyopia occurs as the protein composition of the crystalline lens changes, making it harder and less flexible. When the crystalline lens loses its ability to flex, it is ...
A 28-year-old healthy woman underwent implantation of a posterior chamber, phakic, toric implantable Collamer lens (ICL; STAAR Surgical, Nidau, Switzerland) in both eyes for correction of bilateral high myopia with astigmatism. Preoperatively, best-corrected visual acuity was 20/30 in the right eye with a refraction of −14.50 −3.50 × 15 and 20/20 in the left eye with a refraction of −12.50 −2.75 × 160. Slit-lamp examination of the anterior segment was unremarkable. Both pupils were light-reactive and isocoric, with 5 mm diameters under scotopic illumination. Fundus examination showed myopic changes, with no evidence of retinal tear bilaterally. On applanation tonometry, intraocular pressure (IOP) was 14 mm Hg in each eye. The preoperative corneal topography using Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) revealed bilateral regular astigmatism, with no specific findings identified on the anterior or posterior elevation maps. The central corneal thicknesses were 564 ...
Eyeglasses are the simplest and safest way to correct refractive errors. Eyeglass lenses are designed with precise curves to refract light to the degree necessary to compensate for refractive errors. Your eye care professional can prescribe lenses that will provide you with optimal vision. Contact lenses are a safe and effective option if fitted and used properly. They often provide clearer vision, a wider field of vision and greater comfort than glasses. You may not be able to wear contact lenses if you have certain eye conditions. Refractive surgery permanently changes the shape of the cornea. This change in eye shape restores the focusing power of the eye by allowing the light rays to focus precisely on the retina for improved vision. There are several types of refractive surgeries, but the most popular are: ...
To investigate wavefront aberrations in the entire eye and in the internal optics (lens) and retinal image qualities according to different lenticular opacity types and densities. Forty-one eyes with nuclear cataract, 33 eyes with cortical cataract, and 29 eyes with posterior subcapsular cataract were examined. In each group, wavefront aberrations in the entire eye and in the internal optics and retinal image quality were measured using a raytracing aberrometer. Eyes with cortical cataracts showed significantly higher coma-like aberrations compared to the other two groups in both entire eye and internal optic aberrations (P = 0 ...
Dr Duzman has years of experience in correcting refractive errors, cataract, glaucoma, Astigmatism, Myopia, nearsightedness, Hyperopia, farsightedness, presbyopia, Diabetic retinopathy, Age-related macular degeneration (AMD), macular degeneration, vitreous floaters, posterior vitreous detachment.
Looking for online definition of anisometropia in the Medical Dictionary? anisometropia explanation free. What is anisometropia? Meaning of anisometropia medical term. What does anisometropia mean?
Fig 7: ICL placed behind the iris and in front of the lens Fig 8: Post-op slit lamp view of ICL. Discussion: At our hospital,i we have treated 110 eyes of 63 patients of which 23% were males and 77% females. Spherical ICL was implanted in 25% and Toric ICL in 75% of the eyes. Degree of myopia ranged from -2.5 to - 22.5 DS. The highest cylindrical power treated was -5.5 D. Though most patients had a myopic refractive error, we have also done 3 eyes who received ICL after C3R treatment for keratoconus while 2 eyes had hyperopia with astigmatism. 95% recovered BCVA in 1-2 days. 100% recovered BCVA by 1 week. Various studies have reported that phakic TICL implantation is a good option for the correction of moderate to high myopia, 4,5 hyperopia,6 high myopic astigmatism, in eyes with keratoconus 7,8 , correction of hyperopia post radial keratotomy 9,10 and post penetrating keratoplasy 11. ...

Comparison of central corneal thickness in myopes, hyperopes and emmetropes of different age groups.Comparison of central corneal thickness in myopes, hyperopes and emmetropes of different age groups.

... , Lavanya Kalikivayi, ... Myopia is characterized as spherical equivalent ≤ −0.50 D and hyperopia as ≥ +0.50 D. The measurements were taken by a ... As myopes and hyperopes tend to have longer and shorter axial lengths respectively, can result in inappropriate treatment plan ... Cornea is the major refractive element of the eye where it contributes approximately two-thirds of optical refraction [1]. For ...
more infohttp://www.alliedacademies.org/articles/comparison-of-central-corneal-thickness-in-myopes-hyperopes-and-emmetropes-of-different-age-groups-10887.html

Peripheral Refraction and Refractive Error in Singapore Chinese Children | IOVS | ARVO JournalsPeripheral Refraction and Refractive Error in Singapore Chinese Children | IOVS | ARVO Journals

Axial Length. Temporal Spherical Equivalent (30°) Temporal Spherical Equivalent (15°) Central Spherical Equivalent Nasal ... Purpose.: Peripheral hyperopia was hypothesized to stimulate axial elongation. This study describes peripheral refraction and ... high myope, low myope, emmetrope, hyperope), sex (male, female) and age (≤72 months, ,72 months) were examined with repeated ... Temporal Spherical Equivalent (15°) Central Spherical Equivalent Nasal Spherical Equivalent (15°) Nasal Spherical Equivalent ( ...
more infohttps://iovs.arvojournals.org/article.aspx?articleid=2126576

Association of Birth Parameters with Refractive Status in a Sample of Caucasian Children Aged 4-17 YearsAssociation of Birth Parameters with Refractive Status in a Sample of Caucasian Children Aged 4-17 Years

The average value was recorded and the refraction was expressed as spherical equivalent (SE). The SE is the sum of spherical ... Also, when the cut-off for birth weight is chosen as 2500 grams, the myopes had significantly higher BWs above 2500 grams than ... Lower BW tended to have shorter axial length and steeper corneas [21]. In our study, hypermetropia was more common in SGA ... Emmetropia was defined between −0.5 and +0.5 D, myopia as less than −0.5, and hyperopia as more than +0.5, respectively. They ...
more infohttps://www.hindawi.com/journals/joph/2015/635682/

Intraocular pressure associations with refractive error and axial length in children | British Journal of OphthalmologyIntraocular pressure associations with refractive error and axial length in children | British Journal of Ophthalmology

IOP was not correlated with spherical equivalent refraction (Spearman correlation, r = 0.009) or axial length (r = 0.030). In ... 7 Change in IOP was not correlated with change in refraction in pre-existing myopes, the investigators concluding that ... The mean IOP in children with hyperopia (16.7 mm Hg), emmetropia (16.7 mm Hg), low myopia (16.4 mm Hg), and high myopia (16.7 ... For analyses, refractive error was categorised into four groups; hypermetropia (spherical equivalent refraction (SE) ⩾+1.0D), ...
more infohttp://bjo.bmj.com/content/88/1/5

Phakic intraocular lens - WikipediaPhakic intraocular lens - Wikipedia

Rather it depends on central corneal power, anterior chamber depth (ACD) and patient refraction (preoperative spherical ... Although PIOLs for hyperopia are being investigated, there is less enthusiasm for these lenses because the anterior chamber ... The power of phakic lens is independent of the axial length of the eye. ... especially very high myopes and older patients. Endothelial cell loss especially for the anterior chamber PIOLs. A study ...
more infohttps://en.wikipedia.org/wiki/Phakic_intraocular_lens

Putting myopia control into practicePutting myopia control into practice

... to watch these at-risk future myopes closely for shifts in their risk profile and especially in their manifest hyperopia. ... Refractive error, axial length, and relative peripheral refractive error before and after the onset of myopia. Invest ... Having determined a childs best distance refraction, it is imperative to know how this influences their near point binocular ... spherical aberration and binocular vision, and would likely be best suited to a contact lens modality. It may also include real ...
more infohttps://www.aop.org.uk/ot/CET/2016/06/20/putting-myopia-control-into-practice/article

Oman Journal of OphthalmologyOman Journal of Ophthalmology

The mean preoperative spherical equivalent (SE) was -17.52D (range, -12.25 to -30.50D). After surgery, the mean spherical ... calculation formulas in predicting a target postoperative refraction ± 1.0D (Diopters) in patients with long eyes (axial length ... However, Haigis formula showed the least deviation while SRK-T and other formulas showed a greater tendency toward hyperopia. ... It can occur in emmetropes, hypermetropes and myopes. All the physiological changes that occur in normal accommodation are ...
more infohttp://www.ojoonline.org/showstats.asp?sabs=y&a=ts

Retinal peripheral changes after LASIKRetinal peripheral changes after LASIK

... spherical equivalent refraction with cycloplegia was -7.75D (range -0.75 to -17.25). According to the preoperative spherical ... Most myopes have increased axial length; vitreous and peripheral fundus abnormalities in myopic eyes are the major factors that ... 3. Ibrahim O. Laser in situ keratomileusis for hyperopia and hyperopic astigmatism. J Refract Surg 1998; 14(2 Suppl): S179-82 ... Mean spherical equivalent was 7.75D (range 1.00 to -17.25D). Before LASIK, preventive treatment was carried out on predisposing ...
more infohttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0034-72802008000300005&lng=en&nrm=iso&tlng=en

Influence of Overnight Orthokeratology on Axial Elongation in Childhood Myopia | IOVS | ARVO JournalsInfluence of Overnight Orthokeratology on Axial Elongation in Childhood Myopia | IOVS | ARVO Journals

At baseline, the spherical equivalent refractive error was −2.55 ± 1.82 and −2.59 ± 1.66 D, and the axial length was 24.66 ± ... 43 reported that myopic children have greater relative hyperopia in the periphery with respect to axial refraction, indicating ... 1, 2), the distributions of axial growth were similar in both groups for low baseline myopes, showing a wide variety of ... Increases in axial length and spherical equivalent refractive errors at baseline in the OK group. A significant correlation was ...
more infohttps://iovs.arvojournals.org/article.aspx?articleid=2126672

A-Scan Biometry: Ultrasound Principles, Ultrasound Biometry Instrumentation, Accuracy and Standard DimensionsA-Scan Biometry: Ultrasound Principles, Ultrasound Biometry Instrumentation, Accuracy and Standard Dimensions

High myope with a long eye. Note the poor quality of the retinal spike on the A-scan. The axial length from the anterior ... 3] The data needed in this method include the spherical equivalent refractive error prior to refractive surgery, the average ... If the silicone oil is to be left in the eye permanently, power must be added to account for the index of refraction of the ... and LSE was 3 D of hyperopia, +3 X (-0.326) + 0.101 = -0.877, which is added to the calculated implant power of +22 D, for a ...
more infohttps://emedicine.medscape.com/article/1228447-overview

Scanning laser polarimetry in normal subjects and patients with myopia | British Journal of OphthalmologyScanning laser polarimetry in normal subjects and patients with myopia | British Journal of Ophthalmology

Myopic patients had a mean spherical equivalent refractive error of -4.56D (SD 2.72D) (range −1.00 to −15.00D); 21 of them had ... was also shown to be greater than that in either emmetropia or hyperopia (1%).15 NFL retardation in myopes may therefore be ... and visual field defects are more pronounced in glaucoma patients with long axial lengths than in those with short axial ... A) Nomogram for the ratio of the superior to nasal NFL thickness plotted against the refraction (minus dioptres) of the myopic ...
more infohttp://bjo.bmj.com/content/84/3/264

Myopia and peripheral ocular aberrations | JOV | ARVO JournalsMyopia and peripheral ocular aberrations | JOV | ARVO Journals

... young myopes, and (C) difference B − A. The spherical equivalent M across the field for any group is relative to the mean axial ... Mean spherical aberration coefficient C 4 0 as a function of the mean spherical refraction of the individual myopic subjects. ... blurred axial retinal image, or as a result of relative peripheral hyperopia, where abnormal axial growth of the eye is caused ... The spherical equivalent M across the field for any group is relative to the mean axial spherical equivalent for that group (i. ...
more infohttp://jov.arvojournals.org/article.aspx?articleid=2122148&resultClick=1

Oman Journal of OphthalmologyOman Journal of Ophthalmology

The mean preoperative spherical equivalent (SE) was -17.52D (range, -12.25 to -30.50D). After surgery, the mean spherical ... calculation formulas in predicting a target postoperative refraction ± 1.0D (Diopters) in patients with long eyes (axial length ... However, Haigis formula showed the least deviation while SRK-T and other formulas showed a greater tendency toward hyperopia. ... It can occur in emmetropes, hypermetropes and myopes. All the physiological changes that occur in normal accommodation are ...
more infohttp://www.ojoonline.org/showstats.asp?a=ts

EuroTimes Vol. 19 - Issue 5 by EUROTIMES - issuuEuroTimes Vol. 19 - Issue 5 by EUROTIMES - issuu

... the iris-fixated IOL was combined with LASIK to correct hyperopia in 39 eyes with a mean preoperative spherical equivalent of ... By eight weeks follow-up the eye had a corrected distance visual acuity of 20/20 and refraction in that eye was equivalent to ... She added that clear lens removal is less risky for the retina in high hyperopes than it is in high myopes, and it is the only ... The ALADDIN combines axial length, corneal topography, pupillometry, corneal diameter and anterior chamber depth in one single ...
more infohttps://issuu.com/eurotimes/docs/et19-5

Full text] Visual performance with multifocal soft contact lenses in non-presbyop | OPTOFull text] Visual performance with multifocal soft contact lenses in non-presbyop | OPTO

The lens power for all lenses was selected based on the spherical equivalent of the distance subjective refraction performed at ... Perera SA, Wong TY, Tay WT, Foster PJ, Saw SM, Aung T. Refractive error, axial dimensions, and primary open-angle glaucoma: the ... Differences in the accommodation stimulus response curves of adult myopes and emmetropes. Ophthalmic Physiol Opt. 1998;18:13-20 ... Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: one-year results. ...
more infohttps://www.dovepress.com/visual-performance-with-multifocal-soft-contact-lenses-in-non-presbyop-peer-reviewed-fulltext-article-OPTO

Lasik Eye Surgery • View topic - PRK or Intacs for my -5 myopia.Lasik Eye Surgery • View topic - PRK or Intacs for my -5 myopia.

It also says I have almost -6d of spherical equivalent. I am more like a -5.5 though. I also got an orbscan that shows the ... Would the axial length of the eye factor into the calculations for PRK like it does for IOLs?. 2. How much would a guarantee ... done for extreme myopes who arent good candidates for lasik/PRK. Some say that IOLs. are actually *more* risky than lasik, so ... Allow 3+ months for right eye to heal, repeat left eye with a target of -1.5d(-0.5d to -2.5d range) post prk refraction. Allow ...
more infohttps://www.usaeyes.org/ask-lasik-expert/viewtopic.php?p=11529

Contact Lens Spectrum - Myopia Control in 2019Contact Lens Spectrum - Myopia Control in 2019

... spherical equivalent of the distance manifest refraction. An over-refraction incorporated into the distance power of the soft ... Orthokeratology contact lenses may result in slower axial elongation for higher myopes, but controversy exists in that regard, ... Decrease in rate of myopia progression with a contact lens designed to reduce relative peripheral hyperopia: one-year results. ... correction found that myopes who wore no correction exhibited slower myopia progression and axial elongation compared to myopes ...
more infohttps://www.clspectrum.com/issues/2019/march-2019/myopia-control-in-2019

Lasik and Myopia | Lasik IndiaLasik and Myopia | Lasik India

While excellent surgical options exist for the treatment of low (3.00 D or less of myopic spherical equivalent error) to ... Phakic IOLs are a great option for myopes between -5.00 D to -20.00 D younger than age 40 years without cataract but with mild- ... For unclear reasons, certain modern IOL formulas tend to result in postoperative hyperopia, which may result from a more ... Regardless of the cause, using different tools such as an intraoperative aberrometer or an optimized axial length (AL) formula ...
more infohttps://www.lasikindia.in/lasik-enough-myopia/

Prevalence and Related Factors for Myopia in School-Aged Children in QingdaoPrevalence and Related Factors for Myopia in School-Aged Children in Qingdao

Spherical equivalent (SE) was calculated with the following equation: SE = spherical diopter +0.5 × cylinder diopter. Myopia, ... E. C. Woodman, S. A. Read, M. J. Collins et al., "Axial elongation following prolonged near work in myopes and emmetropes," ... 16] reported that outdoor activities were associated with less myopic refraction, but they did not find any significant ... emmetropia, and hyperopia was defined as the SE , −0.50 D (low myopia , −0.5 to ,−3.0 D, moderate myopia ≤ −3.0 to ,−6.0 D, and ...
more infohttps://www.hindawi.com/journals/joph/2018/9781987/

Search of: ASTIGMATISM - List Results - ClinicalTrials.govSearch of: ASTIGMATISM - List Results - ClinicalTrials.gov

A minimum of 95% of eyes should have a change of , 1.00 D in manifest refraction spherical equivalent (MRSE) between 2 ... Prevalence of axial length. 808. All. 40 Years to 100 Years (Adult, Senior). NCT03159780. ZhongshanOC20170503. January 1, 2017 ... Safety and Efficacy of Corneal Collagen Cross-linking Following LASIK for Treatment of Hyperopia and Hyperopic Astigmatism. * ... Assessment of Conjunctival Hyperemia in Subjects That Are High Myopes (Have a High Degree of Nearsightedness) ...
more infohttps://clinicaltrials.gov/ct2/results?cond=ASTIGMATISM&show_flds=Y

US Patent # 1,001,2848. Mask lens design and method for preventing and/or slowing myopia
     progression - Patents.comUS Patent # 1,001,2848. Mask lens design and method for preventing and/or slowing myopia progression - Patents.com

Hyperopia typically develops because the axial length of the eye is too short compared with the focal length of the optical ... Ghosh et al 2012 (Axial Length Changes with Shifts of Gaze Direction in Myopes and Emmetropes, IOVS, September 2012, VOL. 53, ... causes the spherical aberration to change from positive to negative. As noted, myopia typically occurs due to excessive axial ... An ophthalmic lens is provided with a power profile having substantially equivalent foveal vision correction to a single vision ...
more infohttp://patents.com/us-10012848.html

Lensing | definition of lensing by Medical dictionaryLensing | definition of lensing by Medical dictionary

equivalent lens See spherical equivalent.. lens exfoliation See exfoliation of the lens.. extended wear lens A contact lens ... In farsightedness (hyperopia) the image is focused behind the retina because the refractive power of the lens is too weak or ... A hyperope will see a blue spot surrounded by a red annulus and a myope will see a red spot surrounded by a blue annulus. An ... a transparent body at the front of the vertebrate eye, the main function of which is ACCOMMODATION and not refraction, though ...
more infohttps://medical-dictionary.thefreedictionary.com/lensing

Stokess l | definition of Stokess l by Medical dictionaryStokes's l | definition of Stokes's l by Medical dictionary

equivalent lens See spherical equivalent.. lens exfoliation See exfoliation of the lens.. extended wear lens A contact lens ... In farsightedness (hyperopia) the image is focused behind the retina because the refractive power of the lens is too weak or ... A hyperope will see a blue spot surrounded by a red annulus and a myope will see a red spot surrounded by a blue annulus. An ... a transparent body at the front of the vertebrate eye, the main function of which is ACCOMMODATION and not refraction, though ...
more infohttps://medical-dictionary.thefreedictionary.com/Stokes%27s+l

Edward Manche, MD | Stanford Medicine ProfilesEdward Manche, MD | Stanford Medicine Profiles

The mean preoperative spherical equivalent (SE) refraction was -3.89 diopters (D) ± 1.67 (SD) and -4.18 ± 1.73 D in the small- ... and high hyperopia (more than +4.00 D).In all eyes, the mean preoperative spherical equivalent (SE) was +2.53 D (range +0.75 to ... Changes in spherical equivalence, axial length, and central keratometry readings were not statistically significant. There were ... OBJECTIVE: To compare wavefront (WF)-guided and WF-optimized LASIK in myopes. DESIGN: Prospective, randomized, eye-to-eye study ...
more infohttps://med.stanford.edu/profiles/edward-manche

Uniformity of accommodation across the visual field | JOV | ARVO JournalsUniformity of accommodation across the visual field | JOV | ARVO Journals

Subsequent aberrometry measurements confirmed the emmetropic status (mean of spherical equivalent refraction = 0.2 D, standard ... Peripheral refraction for distance and near vision in emmetropes and myopes. Ophthalmic and Physiological Optics, 27 (6), 584- ... Prior work suggests the mean axial location of fundus reflection is slightly posterior to the cone entrance apertures (Teel, ... "peripheral relative hyperopia" for all states of accommodation. A variety of patterns unique to each individual were observed, ...
more infohttps://jov.arvojournals.org/article.aspx?articleid=2488411
  • and an opaque mask beginning at a radial distance from the center, thereby providing a lens power profile having substantially equivalent foveal vision correction to a single vision lens, and having a depth of focus and reduced retinal image quality sensitivity that slows, retards, or prevents myopia progression. (patents.com)
  • According to FDA approximately 6% to 7% of eyes develop anterior subcapsular opacities at 7+ years following Implantable Collamer Lens implantation and 1% to 2% progress to clinically significant cataract during the same period, especially very high myopes and older patients. (wikipedia.org)
  • LASIK is not always a viable option for high myopes, of course, because they may have inadequate residual stromal bed or dry eye disease. (lasikindia.in)
  • In eyes with high axial myopia, depth and stability of the anterior chamber are abnormal, which necessitates the use of dispersive (heavy) viscoelastic material. (biomedcentral.com)
  • 9-11 A key research finding in large-scale studies is that the fastest change in refraction occurs in the year just prior to myopia onset, 10 so it is crucial to watch these at-risk future myopes closely for shifts in their risk profile and especially in their manifest hyperopia. (aop.org.uk)
  • A few studies investigated the association of birth parameters and refraction or biometric parameters in the general population of children [ 14 - 16 ]. (hindawi.com)
  • All children underwent complete ophthalmologic examination including measurement of Snellen visual acuity as decimals, refraction, and dilated funduscopy. (hindawi.com)
  • Mean spherical equivalent was 7.75D (range 1.00 to -17.25D). Before LASIK, preventive treatment was carried out on predisposing lesions to retinal complications, with laser photocoagulation. (scielo.br)
  • The retinal changes found after LASIK in this series of patients, appear to reflect the predisposition of myopes. (scielo.br)
  • 2005 ). Llorente, Barbero, Cano, Dorronsoro, and Marcos ( 2004 ) found higher amounts of aberrations in hypermetropes compared with myopes. (arvojournals.org)
  • If you are cognisant of the rise in myopia, and the risks this entails for the lifelong eye health of each paediatric myope in your practice, then you'll be wondering how to put the vast scientific data on myopia control into practice. (aop.org.uk)
  • Phakic intraocular lenses are contraindicated in patients who do not have a stable refraction for at least 6 months or are 21 years of age or younger. (wikipedia.org)
  • A previous article by this author ( Optometry Today , June 2016) described the pre-myope - the child with a cluster of risk factors for future development of myopia. (aop.org.uk)
  • Accuracy and Precision of Objective Refraction from Wavefront Aberrations", Journal of Vision, Volumber 4, pp. 329-351 (2004). (patents.com)