The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of EYE DISEASES; OPTIC NERVE DISEASES; OPTIC CHIASM diseases; or BRAIN DISEASES affecting the VISUAL PATHWAYS or OCCIPITAL LOBE.
Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)
Total loss of vision in all or part of the visual field due to bilateral OCCIPITAL LOBE (i.e., VISUAL CORTEX) damage or dysfunction. Anton syndrome is characterized by the psychic denial of true, organic cortical blindness. (Adams et al., Principles of Neurology, 6th ed, p460)
Vision considered to be inferior to normal vision as represented by accepted standards of acuity, field of vision, or motility. Low vision generally refers to visual disorders that are caused by diseases that cannot be corrected by refraction (e.g., MACULAR DEGENERATION; RETINITIS PIGMENTOSA; DIABETIC RETINOPATHY, etc.).
Filarial infection of the eyes transmitted from person to person by bites of Onchocerca volvulus-infected black flies. The microfilariae of Onchocerca are thus deposited beneath the skin. They migrate through various tissues including the eye. Those persons infected have impaired vision and up to 20% are blind. The incidence of eye lesions has been reported to be as high as 30% in Central America and parts of Africa.
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)
Persons with loss of vision such that there is an impact on activities of daily living.
Dryness of the eye surfaces caused by deficiency of tears or conjunctival secretions. It may be associated with vitamin A deficiency, trauma, or any condition in which the eyelids do not close completely.
A chronic infection of the CONJUNCTIVA and CORNEA caused by CHLAMYDIA TRACHOMATIS.
Transmission of gene defects or chromosomal aberrations/abnormalities which are expressed in extreme variation in the structure or function of the eye. These may be evident at birth, but may be manifested later with progression of the disorder.
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.
Diseases affecting the eye.
Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).
An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)
The removal of a cataractous CRYSTALLINE LENS from the eye.
Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus.
A nutritional condition produced by a deficiency of VITAMIN A in the diet, characterized by NIGHT BLINDNESS and other ocular manifestations such as dryness of the conjunctiva and later of the cornea (XEROPHTHALMIA). Vitamin A deficiency is a very common problem worldwide, particularly in developing countries as a consequence of famine or shortages of vitamin A-rich foods. In the United States it is found among the urban poor, the elderly, alcoholics, and patients with malabsorption. (From Cecil Textbook of Medicine, 19th ed, p1179)
Damage or trauma inflicted to the eye by external means. The concept includes both surface injuries and intraocular injuries.
Recording of electric potentials in the retina after stimulation by light.
Degenerative changes in the RETINA usually of older adults which results in a loss of vision in the center of the visual field (the MACULA LUTEA) because of damage to the retina. It occurs in dry and wet forms.
Diseases of the cornea.
I'm sorry for any confusion, but "Nepal" is not a medical term that has a definition in the field of medicine. It is actually the name of a country located in South Asia, known officially as the Federal Democratic Republic of Nepal. If you have any questions related to medicine or health, I would be happy to try and help answer those for you!
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.
Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.
A species of parasitic nematodes widely distributed throughout central Africa and also found in northern South America, southern Mexico, and Guatemala. Its intermediate host and vector is the blackfly or buffalo gnat.
Atrophy of the optic disk which may be congenital or acquired. This condition indicates a deficiency in the number of nerve fibers which arise in the RETINA and converge to form the OPTIC DISK; OPTIC NERVE; OPTIC CHIASM; and optic tracts. GLAUCOMA; ISCHEMIA; inflammation, a chronic elevation of intracranial pressure, toxins, optic nerve compression, and inherited conditions (see OPTIC ATROPHIES, HEREDITARY) are relatively common causes of this condition.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
Retinal diseases refer to a diverse group of vision-threatening disorders that affect the retina's structure and function, including age-related macular degeneration, diabetic retinopathy, retinal detachment, retinitis pigmentosa, and macular edema, among others.
A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.
Disorder occurring in the central or peripheral area of the cornea. The usual degree of transparency becomes relatively opaque.
Disease of the RETINA as a complication of DIABETES MELLITUS. It is characterized by the progressive microvascular complications, such as ANEURYSM, interretinal EDEMA, and intraocular PATHOLOGIC NEOVASCULARIZATION.
A retrogressive pathological change in the retina, focal or generalized, caused by genetic defects, inflammation, trauma, vascular disease, or aging. Degeneration affecting predominantly the macula lutea of the retina is MACULAR DEGENERATION. (Newell, Ophthalmology: Principles and Concepts, 7th ed, p304)
Hereditary, progressive degeneration of the neuroepithelium of the retina characterized by night blindness and progressive contraction of the visual field.
Genetic diseases that are linked to gene mutations on the X CHROMOSOME in humans (X CHROMOSOME, HUMAN) or the X CHROMOSOME in other species. Included here are animal models of human X-linked diseases.
I'm sorry for any confusion, but "India" is not a medical term that can be defined in a medical context. It is a geographical location, referring to the Republic of India, a country in South Asia. If you have any questions related to medical topics or definitions, I would be happy to help with those!
Infection with nematodes of the genus ONCHOCERCA. Characteristics include the presence of firm subcutaneous nodules filled with adult worms, PRURITUS, and ocular lesions.
Transient complete or partial monocular blindness due to retinal ischemia. This may be caused by emboli from the CAROTID ARTERY (usually in association with CAROTID STENOSIS) and other locations that enter the central RETINAL ARTERY. (From Adams et al., Principles of Neurology, 6th ed, p245)
'Eye proteins' are structural or functional proteins, such as crystallins, opsins, and collagens, located in various parts of the eye, including the cornea, lens, retina, and aqueous humor, that contribute to maintaining transparency, refractive power, phototransduction, and overall integrity of the visual system.
Inflammation of the cornea.
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.
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
Glaucoma in which the angle of the anterior chamber is open and the trabecular meshwork does not encroach on the base of the iris.
Absence of crystalline lens totally or partially from field of vision, from any cause except after cataract extraction. Aphakia is mainly congenital or as result of LENS DISLOCATION AND SUBLUXATION.
A rare degenerative inherited eye disease that appears at birth or in the first few months of life that results in a loss of vision. Not to be confused with LEBER HEREDITARY OPTIC NEUROPATHY, the disease is thought to be caused by abnormal development of PHOTORECEPTOR CELLS in the RETINA, or by the extremely premature degeneration of retinal cells.
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)
A republic in western Africa, south of NIGER between BENIN and CAMEROON. Its capital is Abuja.
Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.
A disease of the eye in which the eyelashes abnormally turn inwards toward the eyeball producing constant irritation caused by motion of the lids.
The status of health in rural populations.
Education of the individual who markedly deviates intellectually, physically, socially, or emotionally from those considered to be normal, thus requiring special instruction.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Enzymes that catalyze the rearrangement of geometry about double bonds. EC 5.2.
Images used to comment on such things as contemporary events, social habits, or political trends; usually executed in a broad or abbreviated manner.
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.
The teaching or training of those individuals with visual disability.
Specialized PHOTOTRANSDUCTION neurons in the vertebrates, such as the RETINAL ROD CELLS and the RETINAL CONE CELLS. Non-visual photoreceptor neurons have been reported in the deep brain, the PINEAL GLAND and organs of the circadian system.
The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.
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.
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.
Inflammation of part or all of the uvea, the middle (vascular) tunic of the eye, and commonly involving the other tunics (sclera and cornea, and the retina). (Dorland, 27th ed)
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.
A purplish-red, light-sensitive pigment found in RETINAL ROD CELLS of most vertebrates. It is a complex consisting of a molecule of ROD OPSIN and a molecule of 11-cis retinal (RETINALDEHYDE). Rhodopsin exhibits peak absorption wavelength at about 500 nm.
A sultanate on the southeast coast of the Arabian peninsula. Its capital is Masqat. Before the 16th century it was ruled by independent emirs but was captured and controlled by the Portuguese 1508-1648. In 1741 it was recovered by a descendent of Yemen's imam. After its decline in the 19th century, it became virtually a political and economic dependency within the British Government of India, retaining close ties with Great Britain by treaty from 1939 to 1970 when it achieved autonomy. The name was recorded by Pliny in the 1st century A.D. as Omana, said to be derived from the founder of the state, Oman ben Ibrahim al-Khalil. (From Webster's New Geographical Dictionary, 1988, p890; Oman Embassy, Washington; Room, Brewer's Dictionary of Names, 1992, p391)
The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)
Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of CAROTENOIDS found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products.
Devices that help people with impaired sensory responses.
An archipelago in Polynesia in the southwest Pacific Ocean, comprising about 150 islands. It is a kingdom whose capital is Nukualofa. It was discovered by the Dutch in 1616, visited by Tasman in 1643, and by Captain Cook in 1773 and 1777. The modern kingdom was established during the reign of King George Tupou I, 1845-93. It became a British protectorate in 1900 and gained independence in 1970. The name Tonga may be of local origin, meaning either island or holy. Its other name, Friendly Islands, was given by Captain Cook from the welcome given him by the natives. (From Webster's New Geographical Dictionary, 1988, p1219 & Room, Brewer's Dictionary of Names, 1992, p549)
A series of tests used to assess various functions of the eyes.
A genus of parasitic nematodes whose organisms live and breed in skin and subcutaneous tissues. Onchocercal microfilariae may also be found in the urine, blood, or sputum.
The concept pertaining to the health status of inhabitants of the world.
A systematic collection of factual data pertaining to health and disease in a human population within a given geographic area.
The ability to respond to segments of the perceptual experience rather than to the whole.
A country in northeastern Africa. The capital is Khartoum.
Type of vision test used to determine COLOR VISION DEFECTS.

Residual vision in the blind field of hemidecorticated humans predicted by a diffusion scatter model and selective spectral absorption of the human eye. (1/57)

The notion of blindsight was recently challenged by evidence that patients with occipital damage and contralateral field defects show residual islands of vision which may be associated with spared neural tissue. However, this possibility could not explain why patients who underwent the resection or disconnection of an entire cerebral hemisphere exhibit some forms of blindsight. We present here a model for the detection of intraocular scatter, which can account for human sensitivity values obtained in the blind field of hemidecorticated patients. The model demonstrates that, under controlled experimental conditions i.e. where the extraocular scatter is eliminated, Lambertian intraocular scatter alone can account for the visual sensitivities reported in these patients. The model also shows that it is possible to obtain a sensitivity in the blind field almost equivalent to that in the good field using the appropriate parameters. Finally, we show with in-vivo spectroreflectometry measurements made in the eyes of our hemidecorticated patients, that the relative drop in middle wavelength sensitivity generally obtained in the blind field of these patients can be explained by selective intraocular spectral absorption.  (+info)

Cortical blindness and seizures in a patient receiving FK506 after bone marrow transplantation. (2/57)

A 54-year-old woman with a myelodysplastic syndrome treated with high-dose chemotherapy and an allogenic bone marrow transplant developed acute cortical blindness while receiving tacrolimus (FK506). MRI showed white matter abnormalities. After discontinuation of FK506, the patient's vision returned within 8 days. FK506 neurotoxicity is similar to cyclosporine neurotoxicity and can occur in allogenic bone marrow transplant patients treated with FK506.  (+info)

Chronic cortical visual impairment in children: aetiology, prognosis, and associated neurological deficits. (3/57)

BACKGROUND/AIMS: To evaluate prevalence, aetiology, prognosis, and associated neurological and ophthalmological problems in children with cortical visual impairment (CVI). METHODS: The records of 7200 outpatients seen in the paediatric ophthalmology practice over the past 15 years were reviewed in order to compile data concerning CVI. In addition, the authors devised and applied a system for grading visual recovery in order to assess prognosis. RESULTS: CVI occurred in 2.4% of all patients examined. The four most common causes of CVI were perinatal hypoxia (22%), cerebral vascular accident (14%), meningitis (12%), and acquired hypoxia (10%). Most children with CVI had associated neurological abnormalities. The most common were seizures (53%), cerebral palsy (26%) hemiparesis (12%), and hypotonia (5%). Associated ophthalmological problems were esotropia (19%), exotropia (18%), optic nerve atrophy (16%), ocular motor apraxia (15%), nystagmus (11%), and retinal disease (3%). On average, CVI patients improved by two levels as measured by the authors' scale. CONCLUSION: The majority of children with CVI showed at least some recovery. In this group of children, CVI is often accompanied by additional ophthalmological problems and is nearly always associated with other, serious neurological abnormalities.  (+info)

Visual perception of motion, luminance and colour in a human hemianope. (4/57)

Human patients rendered cortically blind by lesions to V1 can nevertheless discriminate between visual stimuli presented to their blind fields. Experimental evidence suggests that two response modes are involved. Patients are either unaware or aware of the visual stimuli, which they are able to discriminate. However, under both conditions patients insist that they do not see. We investigate the fundamental difference between percepts derived for the normal and affected hemifield in a human hemianope with visual stimuli of which he was aware. The psychophysical experiments we employed required the patient, GY, to make comparisons between stimuli presented in his affected and normal hemifields. The subject discriminated between, and was allowed to match, the stimuli. Our study reveals that the stimulus parameters of colour and motion can be discriminated and matched between the normal and blind hemifields, whereas brightness cannot. We provide evidence for associations between the percepts of colour and motion, but a dissociation between the percepts of brightness, derived from the normal and hemianopic fields. Our results are consistent with the proposal that the perception of different stimulus attributes is expressed in activity of functionally segregated visual areas of the brain. We also believe our results explain the patient's insistence that he does not see stimuli, but can discriminate between them with awareness.  (+info)

The oculomotor distractor effect in normal and hemianopic vision. (5/57)

The present study investigated the inhibitory effect of visual distractors on the latency of saccades made by hemianopic and normal human subjects. The latency of saccades made by hemianopic subjects to stimuli in their intact visual field was not affected by visual distractors presented within their hemianopic field. In contrast, the latency of saccades made by normal subjects was increased significantly under distractor conditions. The latency increase was larger for temporal than nasal distractors. The results are inconsistent with previous proposals that the crossed retinotectal pathway from the nasal hemiretina to the superior colliculus may mediate a blindsight inhibitory effect when distractors appear within a hemianopic temporal visual field. Instead, the distractor effect appears to reflect the normal processes involved in saccade target selection which may be mediated by a circuit involving both cortical and subcortical structures.  (+info)

Intact verbal description of letters with diminished awareness of their forms. (6/57)

Visual processing and its conscious awareness can be dissociated. To examine the extent of dissociation between ability to read characters or words and to be consciously aware of their forms, reading ability and conscious awareness for characters were examined using a tachistoscope in an alexic patient. A right handed woman with 14 years of education presented with incomplete right hemianopia, alexia with kanji (ideogram) agraphia, anomia, and amnesia. Brain MRI disclosed cerebral infarction limited to the left lower bank of the calcarine fissure, lingual and parahippocampal gyri, and an old infarction in the right medial frontal lobe. Tachistoscopic examination disclosed that she could read characters aloud in the right lower hemifield when she was not clearly aware of their forms and only noted their presence vaguely. Although her performance in reading kanji was better in the left than the right field, she could read kana (phonogram) characters and Arabic numerals equally well in both fields. By contrast, she claimed that she saw only a flash of light in 61% of trials and noticed vague forms of stimuli in 36% of trials. She never recognised a form of a letter in the right lower field precisely. She performed judgment tasks better in the left than right lower hemifield where she had to judge whether two kana characters were the same or different. Although dissociation between performance of visual recognition tasks and conscious awareness of the visual experience was found in patients with blindsight or residual vision, reading (verbal identification) of characters without clear awareness of their forms has not been reported in clinical cases. Diminished awareness of forms in our patient may reflect incomplete input to the extrastriate cortex.  (+info)

Cerebral infarction complicating intravenous immunoglobulin therapy in a patient with Miller Fisher syndrome. (7/57)

Intravenous immunoglobulin (IVIg) therapy is being increasingly used in a wide range of neurological conditions. However, treatment is expensive and side effects may be severe. A patient with Miller Fisher syndrome who developed cortical blindness as a consequence of occipital infarction precipitated by IVIg is reported on.  (+info)

Cortical blindness: an unusual sequela of snake bite. (8/57)

Several ophthalmic effects may follow snake bite; this report describes an instance of cortical blindness that resulted from snake bite.  (+info)

Blindness is a condition of complete or near-complete vision loss. It can be caused by various factors such as eye diseases, injuries, or birth defects. Total blindness means that a person cannot see anything at all, while near-complete blindness refers to having only light perception or the ability to perceive the direction of light, but not able to discern shapes or forms. Legal blindness is a term used to define a certain level of visual impairment that qualifies an individual for government assistance and benefits; it usually means best corrected visual acuity of 20/200 or worse in the better eye, or a visual field no greater than 20 degrees in diameter.

Night blindness, also known as nyctalopia, is a visual impairment characterized by the inability to see well in low light or darkness. It's not an eye condition itself but rather a symptom of various underlying eye disorders, most commonly vitamin A deficiency and retinal diseases like retinitis pigmentosa.

In a healthy eye, a molecule called rhodopsin is present in the rods (special light-sensitive cells in our eyes responsible for vision in low light conditions). This rhodopsin requires sufficient amounts of vitamin A to function properly. When there's a deficiency of vitamin A or damage to the rods, the ability to see in dim light gets affected, leading to night blindness.

People with night blindness often have difficulty adjusting to changes in light levels, such as when entering a dark room from bright sunlight. They may also experience trouble seeing stars at night, driving at dusk or dawn, and navigating in poorly lit areas. If you suspect night blindness, it's essential to consult an eye care professional for proper diagnosis and treatment of the underlying cause.

Cortical blindness is a type of visual impairment that is caused by damage to the occipital cortex, which is the part of the brain responsible for processing visual information. This condition is also known as cerebral blindness or cerebral visual impairment.

In cortical blindness, the eyes are able to receive and transmit visual signals to the brain, but the brain is unable to interpret these signals correctly. As a result, the person may have difficulty recognizing objects, faces, or movements in their visual field. They may also experience hallucinations, such as seeing patterns or shapes that aren't really there.

Cortical blindness can be caused by a variety of factors, including stroke, trauma, brain tumors, infection, or hypoxia (lack of oxygen). In some cases, cortical blindness may be temporary and improve over time with treatment and rehabilitation. However, in other cases, the damage to the occipital cortex may be permanent, leading to a lifelong visual impairment.

It is important to note that cortical blindness is different from legal blindness, which is a term used to describe a severe visual impairment that cannot be corrected with glasses or contact lenses. In contrast, cortical blindness is a neurological condition that affects the brain's ability to process visual information, rather than a problem with the eyes themselves.

Low vision is a term used to describe significant visual impairment that cannot be corrected with standard glasses, contact lenses, medication or surgery. It is typically defined as visual acuity of less than 20/70 in the better-seeing eye after best correction, or a visual field of less than 20 degrees in the better-seeing eye.

People with low vision may have difficulty performing everyday tasks such as reading, recognizing faces, watching television, driving, or simply navigating their environment. They may also experience symptoms such as sensitivity to light, glare, or contrast, and may benefit from the use of visual aids, assistive devices, and rehabilitation services to help them maximize their remaining vision and maintain their independence.

Low vision can result from a variety of causes, including eye diseases such as macular degeneration, diabetic retinopathy, glaucoma, or cataracts, as well as congenital or inherited conditions, brain injuries, or aging. It is important for individuals with low vision to receive regular eye examinations and consult with a low vision specialist to determine the best course of treatment and management.

Onchocerciasis, Ocular is a medical condition that specifically refers to the eye manifestations caused by the parasitic infection, Onchocerca volvulus. Also known as "river blindness," this disease is spread through the bite of infected blackflies.

Ocular onchocerciasis affects various parts of the eye, including the conjunctiva, cornea, iris, and retina. The infection can cause symptoms such as itching, burning, and redness of the eyes. Over time, it may lead to more serious complications like punctate keratitis (small, scattered opacities on the cornea), cataracts, glaucoma, and ultimately, blindness.

The infection is diagnosed through a skin snip or blood test, which can detect the presence of microfilariae (the larval stage of the parasite) or antibodies against the parasite. Treatment typically involves administering oral medications such as ivermectin, which kills the microfilariae and reduces the risk of eye damage. However, it does not kill the adult worms, so multiple doses are often required to control the infection. In some cases, surgery may be necessary to remove advanced ocular lesions.

A cataract is a clouding of the natural lens in the eye that affects vision. This clouding can cause vision to become blurry, faded, or dim, making it difficult to see clearly. Cataracts are a common age-related condition, but they can also be caused by injury, disease, or medication use. In most cases, cataracts develop gradually over time and can be treated with surgery to remove the cloudy lens and replace it with an artificial one.

Medical definitions for visual impairment often vary, but according to the World Health Organization (WHO), visually impaired persons are those who have a best-corrected visual acuity of less than 0.3 (6/12) in their better eye or a visual field of less than 20 degrees in their better eye. This includes people who are blind, as well as those with partial sight.

Visual impairment can range from mild to severe and may result from a variety of causes, including genetic disorders, diseases, trauma, or aging. It is important to note that visual impairment does not necessarily mean total blindness; many visually impaired individuals have some remaining vision and can benefit from low vision services and assistive devices.

Xerophthalmia is a medical condition characterized by dryness of the conjunctiva and cornea due to vitamin A deficiency. It can lead to eye damage, including night blindness (nyctalopia) and, if left untreated, potentially irreversible blindness. Xerophthalmia is often associated with malnutrition and affects children in low-income countries disproportionately.

Trachoma is a chronic infectious disease caused by the bacterium Chlamydia trachomatis. It primarily affects the eyes, causing repeated infections that lead to scarring of the inner eyelid and eyelashes turning inward (trichiasis), which can result in damage to the cornea and blindness if left untreated.

The disease is spread through direct contact with eye or nose discharge from infected individuals, often through contaminated fingers, shared towels, or flies that have come into contact with the discharge. Trachoma is prevalent in areas with poor sanitation and limited access to clean water, making it a significant public health issue in many developing countries.

Preventive measures include improving personal hygiene, such as washing hands regularly, promoting facial cleanliness, and providing safe water and sanitation facilities. Treatment typically involves antibiotics to eliminate the infection and surgery for advanced cases with trichiasis or corneal damage.

Hereditary eye diseases refer to conditions that affect the eyes and are passed down from parents to their offspring through genetics. These diseases are caused by mutations or changes in an individual's DNA that are inherited from their parents. The mutations can occur in any of the genes associated with eye development, function, or health.

There are many different types of hereditary eye diseases, some of which include:

1. Retinitis Pigmentosa - a group of rare, genetic disorders that involve a breakdown and loss of cells in the retina.
2. Macular Degeneration - a progressive disease that damages the central portion of the retina, impairing vision.
3. Glaucoma - a group of eye conditions that damage the optic nerve, often caused by an increase in pressure inside the eye.
4. Cataracts - clouding of the lens inside the eye, which can lead to blurry vision and blindness.
5. Keratoconus - a progressive eye disease that causes the cornea to thin and bulge outward into a cone shape.
6. Color Blindness - a condition where an individual has difficulty distinguishing between certain colors.
7. Optic Neuropathy - damage to the optic nerve, which can result in vision loss.

The symptoms and severity of hereditary eye diseases can vary widely depending on the specific condition and the individual's genetic makeup. Some conditions may be present at birth or develop in early childhood, while others may not appear until later in life. Treatment options for these conditions may include medication, surgery, or lifestyle changes, and are often most effective when started early.

Visual acuity is a measure of the sharpness or clarity of vision. It is usually tested by reading an eye chart from a specific distance, such as 20 feet (6 meters). The standard eye chart used for this purpose is called the Snellen chart, which contains rows of letters that decrease in size as you read down the chart.

Visual acuity is typically expressed as a fraction, with the numerator representing the testing distance and the denominator indicating the smallest line of type that can be read clearly. For example, if a person can read the line on the eye chart that corresponds to a visual acuity of 20/20, it means they have normal vision at 20 feet. If their visual acuity is 20/40, it means they must be as close as 20 feet to see what someone with normal vision can see at 40 feet.

It's important to note that visual acuity is just one aspect of overall vision and does not necessarily reflect other important factors such as peripheral vision, depth perception, color vision, or contrast sensitivity.

Eye diseases are a range of conditions that affect the eye or visual system, causing damage to vision and, in some cases, leading to blindness. These diseases can be categorized into various types, including:

1. Refractive errors: These include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia, which affect the way light is focused on the retina and can usually be corrected with glasses or contact lenses.
2. Cataracts: A clouding of the lens inside the eye that leads to blurry vision, glare, and decreased contrast sensitivity. Cataract surgery is the most common treatment for this condition.
3. Glaucoma: A group of diseases characterized by increased pressure in the eye, leading to damage to the optic nerve and potential blindness if left untreated. Treatment includes medications, laser therapy, or surgery.
4. Age-related macular degeneration (AMD): A progressive condition that affects the central part of the retina called the macula, causing blurry vision and, in advanced stages, loss of central vision. Treatment may include anti-VEGF injections, laser therapy, or nutritional supplements.
5. Diabetic retinopathy: A complication of diabetes that affects the blood vessels in the retina, leading to bleeding, leakage, and potential blindness if left untreated. Treatment includes laser therapy, anti-VEGF injections, or surgery.
6. Retinal detachment: A separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly with surgery.
7. Amblyopia (lazy eye): A condition where one eye does not develop normal vision, often due to a misalignment or refractive error in childhood. Treatment includes correcting the underlying problem and encouraging the use of the weaker eye through patching or other methods.
8. Strabismus (crossed eyes): A misalignment of the eyes that can lead to amblyopia if not treated promptly with surgery, glasses, or other methods.
9. Corneal diseases: Conditions that affect the transparent outer layer of the eye, such as keratoconus, Fuchs' dystrophy, and infectious keratitis, which can lead to vision loss if not treated promptly.
10. Uveitis: Inflammation of the middle layer of the eye, which can cause vision loss if not treated promptly with anti-inflammatory medications or surgery.

Vision disorders refer to a wide range of conditions that affect the visual system and result in various symptoms, such as blurry vision, double vision, distorted vision, impaired depth perception, and difficulty with visual tracking or focusing. These disorders can be categorized into several types, including:

1. Refractive errors: These occur when the shape of the eye prevents light from focusing directly on the retina, resulting in blurry vision. Examples include myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia (age-related loss of near vision).
2. Strabismus: Also known as crossed eyes or walleye, strabismus is a misalignment of the eyes where they point in different directions, which can lead to double vision or loss of depth perception.
3. Amblyopia: Often called lazy eye, amblyopia is a condition where one eye has reduced vision due to lack of proper visual development during childhood. It may be caused by strabismus, refractive errors, or other factors that interfere with normal visual development.
4. Accommodative disorders: These involve problems with the focusing ability of the eyes, such as convergence insufficiency (difficulty focusing on close objects) and accommodative dysfunction (inability to maintain clear vision at different distances).
5. Binocular vision disorders: These affect how the eyes work together as a team, leading to issues like poor depth perception, eye strain, and headaches. Examples include convergence insufficiency, divergence excess, and suppression.
6. Ocular motility disorders: These involve problems with eye movement, such as nystagmus (involuntary eye movements), strabismus, or restricted extraocular muscle function.
7. Visual processing disorders: These affect the brain's ability to interpret and make sense of visual information, even when the eyes themselves are healthy. Symptoms may include difficulty with reading, recognizing shapes and objects, and understanding spatial relationships.
8. Low vision: This term refers to significant visual impairment that cannot be fully corrected with glasses, contact lenses, medication, or surgery. It includes conditions like macular degeneration, diabetic retinopathy, glaucoma, and cataracts.
9. Blindness: Complete loss of sight in both eyes, which can be caused by various factors such as injury, disease, or genetic conditions.

Glaucoma is a group of eye conditions that damage the optic nerve, often caused by an abnormally high pressure in the eye (intraocular pressure). This damage can lead to permanent vision loss or even blindness if left untreated. The most common type is open-angle glaucoma, which has no warning signs and progresses slowly. Angle-closure glaucoma, on the other hand, can cause sudden eye pain, redness, nausea, and vomiting, as well as rapid vision loss. Other less common types of glaucoma also exist. While there is no cure for glaucoma, early detection and treatment can help slow or prevent further vision loss.

Cataract extraction is a surgical procedure that involves removing the cloudy lens (cataract) from the eye. This procedure is typically performed to restore vision impairment caused by cataracts and improve overall quality of life. There are two primary methods for cataract extraction:

1. Phacoemulsification: This is the most common method used today. It involves making a small incision in the front part of the eye (cornea), inserting an ultrasonic probe to break up the cloudy lens into tiny pieces, and then removing those pieces with suction. After removing the cataract, an artificial intraocular lens (IOL) is inserted to replace the natural lens and help focus light onto the retina.

2. Extracapsular Cataract Extraction: In this method, a larger incision is made on the side of the cornea, allowing the surgeon to remove the cloudy lens in one piece without breaking it up. The back part of the lens capsule is left intact to support the IOL. This technique is less common and typically reserved for more advanced cataracts or when phacoemulsification cannot be performed.

Recovery from cataract extraction usually involves using eye drops to prevent infection and inflammation, as well as protecting the eye with a shield or glasses during sleep for a few weeks after surgery. Most people experience improved vision within a few days to a week following the procedure.

Refractive errors are a group of vision conditions that include nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. These conditions occur when the shape of the eye prevents light from focusing directly on the retina, causing blurred or distorted vision.

Myopia is a condition where distant objects appear blurry while close-up objects are clear. This occurs when the eye is too long or the cornea is too curved, causing light to focus in front of the retina instead of directly on it.

Hyperopia, on the other hand, is a condition where close-up objects appear blurry while distant objects are clear. This happens when the eye is too short or the cornea is not curved enough, causing light to focus behind the retina.

Astigmatism is a condition that causes blurred vision at all distances due to an irregularly shaped cornea or lens.

Presbyopia is a natural aging process that affects everyone as they get older, usually around the age of 40. It causes difficulty focusing on close-up objects and can be corrected with reading glasses, bifocals, or progressive lenses.

Refractive errors can be diagnosed through a comprehensive eye exam and are typically corrected with eyeglasses, contact lenses, or refractive surgery such as LASIK.

Vitamin A deficiency (VAD) is a condition that occurs when there is a lack of vitamin A in the diet. This essential fat-soluble vitamin plays crucial roles in vision, growth, cell division, reproduction, and immune system regulation.

In its severe form, VAD leads to xerophthalmia, which includes night blindness (nyctalopia) and keratomalacia - a sight-threatening condition characterized by dryness of the conjunctiva and cornea, with eventual ulceration and perforation. Other symptoms of VAD may include Bitot's spots (foamy, triangular, white spots on the conjunctiva), follicular hyperkeratosis (goose bump-like bumps on the skin), and increased susceptibility to infections due to impaired immune function.

Vitamin A deficiency is most prevalent in developing countries where diets are often low in animal source foods and high in plant-based foods with low bioavailability of vitamin A. It primarily affects children aged 6 months to 5 years, pregnant women, and lactating mothers. Prevention strategies include dietary diversification, food fortification, and supplementation programs.

Eye injuries refer to any damage or trauma caused to the eye or its surrounding structures. These injuries can vary in severity and may include:

1. Corneal abrasions: A scratch or scrape on the clear surface of the eye (cornea).
2. Chemical burns: Occurs when chemicals come into contact with the eye, causing damage to the cornea and other structures.
3. Eyelid lacerations: Cuts or tears to the eyelid.
4. Subconjunctival hemorrhage: Bleeding under the conjunctiva, the clear membrane that covers the white part of the eye.
5. Hyphema: Accumulation of blood in the anterior chamber of the eye, which is the space between the cornea and iris.
6. Orbital fractures: Breaks in the bones surrounding the eye.
7. Retinal detachment: Separation of the retina from its underlying tissue, which can lead to vision loss if not treated promptly.
8. Traumatic uveitis: Inflammation of the uvea, the middle layer of the eye, caused by trauma.
9. Optic nerve damage: Damage to the optic nerve, which transmits visual information from the eye to the brain.

Eye injuries can result from a variety of causes, including accidents, sports-related injuries, violence, and chemical exposure. It is important to seek medical attention promptly for any suspected eye injury to prevent further damage and potential vision loss.

Electroretinography (ERG) is a medical test used to evaluate the functioning of the retina, which is the light-sensitive tissue located at the back of the eye. The test measures the electrical responses of the retina to light stimulation.

During the procedure, a special contact lens or electrode is placed on the surface of the eye to record the electrical activity generated by the retina's light-sensitive cells (rods and cones) and other cells in the retina. The test typically involves presenting different levels of flashes of light to the eye while the electrical responses are recorded.

The resulting ERG waveform provides information about the overall health and function of the retina, including the condition of the photoreceptors, the integrity of the inner retinal layers, and the health of the retinal ganglion cells. This test is often used to diagnose and monitor various retinal disorders, such as retinitis pigmentosa, macular degeneration, and diabetic retinopathy.

Macular degeneration, also known as age-related macular degeneration (AMD), is a medical condition that affects the central part of the retina, called the macula. The macula is responsible for sharp, detailed vision, which is necessary for activities such as reading, driving, and recognizing faces.

In AMD, there is a breakdown or deterioration of the macula, leading to gradual loss of central vision. There are two main types of AMD: dry (atrophic) and wet (exudative). Dry AMD is more common and progresses more slowly, while wet AMD is less common but can cause rapid and severe vision loss if left untreated.

The exact causes of AMD are not fully understood, but risk factors include age, smoking, family history, high blood pressure, obesity, and exposure to sunlight. While there is no cure for AMD, treatments such as vitamin supplements, laser therapy, and medication injections can help slow its progression and reduce the risk of vision loss.

Corneal diseases are a group of disorders that affect the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an important role in focusing vision, and any damage or disease can cause significant visual impairment or loss. Some common types of corneal diseases include:

1. Keratoconus: A progressive disorder in which the cornea thins and bulges outward into a cone shape, causing distorted vision.
2. Fuchs' dystrophy: A genetic disorder that affects the inner layer of the cornea called the endothelium, leading to swelling, cloudiness, and decreased vision.
3. Dry eye syndrome: A condition in which the eyes do not produce enough tears or the tears evaporate too quickly, causing discomfort, redness, and blurred vision.
4. Corneal ulcers: Open sores on the cornea that can be caused by infection, trauma, or other factors.
5. Herpes simplex keratitis: A viral infection of the cornea that can cause recurrent episodes of inflammation, scarring, and vision loss.
6. Corneal dystrophies: Inherited disorders that affect the structure and clarity of the cornea, leading to visual impairment or blindness.
7. Bullous keratopathy: A condition in which the endothelium fails to pump fluid out of the cornea, causing it to swell and form blisters.
8. Corneal trauma: Injury to the cornea caused by foreign objects, chemicals, or other factors that can lead to scarring, infection, and vision loss.

Treatment for corneal diseases varies depending on the specific condition and severity of the disease. Options may include eyedrops, medications, laser surgery, corneal transplantation, or other treatments.

I'm sorry for any confusion, but "Nepal" is not a medical term. It is a country located in South Asia, between China and India. If you have any questions about medical terminology or health-related topics, I would be happy to try and help answer those for you.

Prevalence, in medical terms, refers to the total number of people in a given population who have a particular disease or condition at a specific point in time, or over a specified period. It is typically expressed as a percentage or a ratio of the number of cases to the size of the population. Prevalence differs from incidence, which measures the number of new cases that develop during a certain period.

Color vision defects, also known as color blindness, are conditions in which a person has difficulty distinguishing between certain colors. The most common types of color vision defects involve the inability to distinguish between red and green or blue and yellow. These deficiencies result from an alteration or absence of one or more of the three types of cone cells in the retina that are responsible for normal color vision.

In red-green color vision defects, there is a problem with either the red or green cones, or both. This results in difficulty distinguishing between these two colors and their shades. Protanopia is a type of red-green color vision defect where there is an absence of red cone cells, making it difficult to distinguish between red and green as well as between red and black or green and black. Deuteranopia is another type of red-green color vision defect where there is an absence of green cone cells, resulting in similar difficulties distinguishing between red and green, as well as between blue and yellow.

Blue-yellow color vision defects are less common than red-green color vision defects. Tritanopia is a type of blue-yellow color vision defect where there is an absence of blue cone cells, making it difficult to distinguish between blue and yellow, as well as between blue and purple or yellow and pink.

Color vision defects are usually inherited and present from birth, but they can also result from eye diseases, chemical exposure, aging, or medication side effects. They affect both men and women, although red-green color vision defects are more common in men than in women. People with color vision defects may have difficulty with tasks that require color discrimination, such as matching clothes, selecting ripe fruit, reading colored maps, or identifying warning signals. However, most people with mild to moderate color vision defects can adapt and function well in daily life.

'Onchocerca volvulus' is a species of parasitic roundworm that is the causative agent of human river blindness, also known as onchocerciasis. This disease is named after the fact that the larval forms of the worm are often found in the rivers and streams where the blackfly vectors breed.

The adult female worms measure about 33-50 cm in length and live in nodules beneath the skin, while the much smaller males (about 4 cm long) move between the nodules. The females release microfilariae, which are taken up by blackflies when they bite an infected person. These larvae then develop into infective stages within the blackfly and can be transmitted to another human host during a subsequent blood meal.

The infection leads to various symptoms, including itchy skin, rashes, bumps under the skin (nodules), and in severe cases, visual impairment or blindness due to damage caused to the eyes by the migrating larvae. The disease is prevalent in certain regions of Africa, Latin America, and Yemen. Preventive measures include avoiding blackfly bites, mass drug administration with anti-parasitic drugs, and vector control strategies.

Optic atrophy is a medical term that refers to the degeneration and shrinkage (atrophy) of the optic nerve, which transmits visual information from the eye to the brain. This condition can result in various vision abnormalities, including loss of visual acuity, color vision deficiencies, and peripheral vision loss.

Optic atrophy can occur due to a variety of causes, such as:

* Traumatic injuries to the eye or optic nerve
* Glaucoma
* Optic neuritis (inflammation of the optic nerve)
* Ischemic optic neuropathy (reduced blood flow to the optic nerve)
* Compression or swelling of the optic nerve
* Hereditary or congenital conditions affecting the optic nerve
* Toxins and certain medications that can damage the optic nerve.

The diagnosis of optic atrophy typically involves a comprehensive eye examination, including visual acuity testing, refraction assessment, slit-lamp examination, and dilated funduscopic examination to evaluate the health of the optic nerve. In some cases, additional diagnostic tests such as visual field testing, optical coherence tomography (OCT), or magnetic resonance imaging (MRI) may be necessary to confirm the diagnosis and determine the underlying cause.

There is no specific treatment for optic atrophy, but addressing the underlying cause can help prevent further damage to the optic nerve. In some cases, vision rehabilitation may be recommended to help patients adapt to their visual impairment.

The retina is the innermost, light-sensitive layer of tissue in the eye of many vertebrates and some cephalopods. It receives light that has been focused by the cornea and lens, converts it into neural signals, and sends these to the brain via the optic nerve. The retina contains several types of photoreceptor cells including rods (which handle vision in low light) and cones (which are active in bright light and are capable of color vision).

In medical terms, any pathological changes or diseases affecting the retinal structure and function can lead to visual impairment or blindness. Examples include age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinitis pigmentosa among others.

Retinal diseases refer to a group of conditions that affect the retina, which is the light-sensitive tissue located at the back of the eye. The retina is responsible for converting light into electrical signals that are sent to the brain and interpreted as visual images. Retinal diseases can cause vision loss or even blindness, depending on their severity and location in the retina.

Some common retinal diseases include:

1. Age-related macular degeneration (AMD): A progressive disease that affects the central part of the retina called the macula, causing blurred or distorted vision.
2. Diabetic retinopathy: A complication of diabetes that can damage the blood vessels in the retina, leading to vision loss.
3. Retinal detachment: A serious condition where the retina becomes separated from its underlying tissue, requiring immediate medical attention.
4. Macular edema: Swelling or thickening of the macula due to fluid accumulation, which can cause blurred vision.
5. Retinitis pigmentosa: A group of inherited eye disorders that affect the retina's ability to respond to light, causing progressive vision loss.
6. Macular hole: A small break in the macula that can cause distorted or blurry vision.
7. Retinal vein occlusion: Blockage of the retinal veins that can lead to bleeding, swelling, and potential vision loss.

Treatment for retinal diseases varies depending on the specific condition and its severity. Some treatments include medication, laser therapy, surgery, or a combination of these options. Regular eye exams are essential for early detection and treatment of retinal diseases.

Ophthalmology is a branch of medicine that deals with the diagnosis, treatment, and prevention of diseases and disorders of the eye and visual system. It is a surgical specialty, and ophthalmologists are medical doctors who complete additional years of training to become experts in eye care. They are qualified to perform eye exams, diagnose and treat eye diseases, prescribe glasses and contact lenses, and perform eye surgery. Some subspecialties within ophthalmology include cornea and external disease, glaucoma, neuro-ophthalmology, pediatric ophthalmology, retina and vitreous, and oculoplastics.

Corneal opacity refers to a condition in which the cornea, the clear front part of the eye, becomes cloudy or opaque. This can occur due to various reasons such as injury, infection, degenerative changes, or inherited disorders. As a result, light is not properly refracted and vision becomes blurred or distorted. In some cases, corneal opacity can lead to complete loss of vision in the affected eye. Treatment options depend on the underlying cause and may include medication, corneal transplantation, or other surgical procedures.

Diabetic retinopathy is a diabetes complication that affects the eyes. It's caused by damage to the blood vessels of the light-sensitive tissue at the back of the eye (retina).

At first, diabetic retinopathy may cause no symptoms or only mild vision problems. Eventually, it can cause blindness. The condition usually affects both eyes.

There are two main stages of diabetic retinopathy:

1. Early diabetic retinopathy. This is when the blood vessels in the eye start to leak fluid or bleed. You might not notice any changes in your vision at this stage, but it's still important to get treatment because it can prevent the condition from getting worse.
2. Advanced diabetic retinopathy. This is when new, abnormal blood vessels grow on the surface of the retina. These vessels can leak fluid and cause severe vision problems, including blindness.

Diabetic retinopathy can be treated with laser surgery, injections of medication into the eye, or a vitrectomy (a surgical procedure to remove the gel-like substance that fills the center of the eye). It's important to get regular eye exams to detect diabetic retinopathy early and get treatment before it causes serious vision problems.

Retinal degeneration is a broad term that refers to the progressive loss of photoreceptor cells (rods and cones) in the retina, which are responsible for converting light into electrical signals that are sent to the brain. This process can lead to vision loss or blindness. There are many different types of retinal degeneration, including age-related macular degeneration, retinitis pigmentosa, and Stargardt's disease, among others. These conditions can have varying causes, such as genetic mutations, environmental factors, or a combination of both. Treatment options vary depending on the specific type and progression of the condition.

Retinitis pigmentosa (RP) is a group of rare, genetic disorders that involve a breakdown and loss of cells in the retina - a light-sensitive tissue located at the back of the eye. The retina converts light into electrical signals which are then sent to the brain and interpreted as visual images.

In RP, the cells that detect light (rods and cones) degenerate more slowly than other cells in the retina, leading to a progressive loss of vision. Symptoms typically begin in childhood with night blindness (difficulty seeing in low light), followed by a gradual narrowing of the visual field (tunnel vision). Over time, this can lead to significant vision loss and even blindness.

The condition is usually inherited and there are several different genes that have been associated with RP. The diagnosis is typically made based on a combination of genetic testing, family history, and clinical examination. Currently, there is no cure for RP, but researchers are actively working to develop new treatments that may help slow or stop the progression of the disease.

X-linked genetic diseases refer to a group of disorders caused by mutations in genes located on the X chromosome. These conditions primarily affect males since they have only one X chromosome and therefore don't have a second normal copy of the gene to compensate for the mutated one. Females, who have two X chromosomes, are typically less affected because they usually have one normal copy of the gene on their other X chromosome.

Examples of X-linked genetic diseases include Duchenne and Becker muscular dystrophy, hemophilia A and B, color blindness, and fragile X syndrome. Symptoms and severity can vary widely depending on the specific condition and the nature of the genetic mutation involved. Treatment options depend on the particular disease but may include physical therapy, medication, or in some cases, gene therapy.

I'm sorry for any confusion, but "India" is not a medical term or concept. It is a country in South Asia, the second-most populous country in the world, known for its rich history, diverse culture, and numerous contributions to various fields including medicine. If you have any questions related to medical topics, I would be happy to help answer them!

Onchocerciasis is a neglected tropical disease caused by the parasitic worm Onchocerca volvulus. The infection is primarily transmitted through the bites of infected blackflies (Simulium spp.) that breed in fast-flowing rivers and streams. The larvae of the worms mature into adults in nodules under the skin, where females release microfilariae that migrate throughout the body, including the eyes.

Symptoms include severe itching, dermatitis, depigmentation, thickening and scarring of the skin, visual impairment, and blindness. The disease is also known as river blindness due to its association with riverside communities where blackflies breed. Onchocerciasis can lead to significant social and economic consequences for affected individuals and communities. Preventive chemotherapy using mass drug administration of ivermectin is the primary strategy for controlling onchocerciasis in endemic areas.

Amaurosis fugax is a medical term that describes a temporary loss of vision in one eye, which is often described as a "shade or curtain falling over the field of vision." It's usually caused by a temporary interruption of blood flow to the retina or optic nerve. This condition is often associated with conditions such as giant cell arteritis, carotid artery stenosis, and cardiovascular disease.

It's important to note that Amaurosis fugax can be a warning sign for a more serious medical event, such as a stroke, so it's essential to seek medical attention promptly if you experience any symptoms of this condition.

Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:

1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.

Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.

Keratitis is a medical condition that refers to inflammation of the cornea, which is the clear, dome-shaped surface at the front of the eye. The cornea plays an essential role in focusing vision, and any damage or infection can cause significant visual impairment. Keratitis can result from various causes, including bacterial, viral, fungal, or parasitic infections, as well as trauma, allergies, or underlying medical conditions such as dry eye syndrome. Symptoms of keratitis may include redness, pain, tearing, sensitivity to light, blurred vision, and a feeling of something foreign in the eye. Treatment for keratitis depends on the underlying cause but typically includes antibiotics, antivirals, or anti-fungal medications, as well as measures to alleviate symptoms and promote healing.

"Age distribution" is a term used to describe the number of individuals within a population or sample that fall into different age categories. It is often presented in the form of a graph, table, or chart, and can provide important information about the demographic structure of a population.

The age distribution of a population can be influenced by a variety of factors, including birth rates, mortality rates, migration patterns, and aging. Public health officials and researchers use age distribution data to inform policies and programs related to healthcare, social services, and other areas that affect the well-being of populations.

For example, an age distribution graph might show a larger number of individuals in the younger age categories, indicating a population with a high birth rate. Alternatively, it might show a larger number of individuals in the older age categories, indicating a population with a high life expectancy or an aging population. Understanding the age distribution of a population can help policymakers plan for future needs and allocate resources more effectively.

Dark adaptation is the process by which the eyes adjust to low levels of light. This process allows the eyes to become more sensitive to light and see better in the dark. It involves the dilation of the pupils, as well as chemical changes in the rods and cones (photoreceptor cells) of the retina. These changes allow the eye to detect even small amounts of light and improve visual acuity in low-light conditions. Dark adaptation typically takes several minutes to occur fully, but can be faster or slower depending on various factors such as age, prior exposure to light, and certain medical conditions. It is an important process for maintaining good vision in a variety of lighting conditions.

Open-angle glaucoma is a chronic, progressive type of glaucoma characterized by the gradual loss of optic nerve fibers and resulting in visual field defects. It is called "open-angle" because the angle where the iris meets the cornea (trabecular meshwork) appears to be normal and open on examination. The exact cause of this condition is not fully understood, but it is associated with increased resistance to the outflow of aqueous humor within the trabecular meshwork, leading to an increase in intraocular pressure (IOP). This elevated IOP can cause damage to the optic nerve and result in vision loss.

The onset of open-angle glaucoma is often asymptomatic, making regular comprehensive eye examinations crucial for early detection and management. Treatment typically involves lowering IOP using medications, laser therapy, or surgery to prevent further optic nerve damage and preserve vision.

Aphakia is a medical condition that refers to the absence of the lens in the eye. This can occur naturally, but it's most commonly the result of surgery to remove a cataract, a cloudy lens that can cause vision loss. In some cases, the lens may not be successfully removed or may be accidentally lost during surgery, leading to aphakia. People with aphakia typically have significant vision problems and may require corrective measures such as glasses, contact lenses, or an intraocular lens implant to improve their vision.

Leber Congenital Amaurosis (LCA) is a group of inherited retinal degenerative disorders that affect the development and function of the retina, a light-sensitive tissue at the back of the eye. It is characterized by severe visual impairment or blindness from birth or early infancy.

The condition is caused by mutations in various genes involved in the normal functioning of photoreceptor cells (rods and cones) in the retina, which are responsible for capturing light and transmitting visual signals to the brain. As a result, the photoreceptors fail to develop properly or degenerate over time, leading to vision loss.

Symptoms of LCA may include roving eye movements (nystagmus), lack of fixation, decreased or absent response to light, and abnormal pupillary reflexes. Some individuals with LCA may also have other ocular abnormalities such as keratoconus, cataracts, or glaucoma.

LCA is typically inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. Currently, there is no cure for LCA, but various treatments such as gene therapy and assistive devices may help improve visual function and quality of life for affected individuals.

Retinopathy of Prematurity (ROP) is a potentially sight-threatening proliferative retinal vascular disorder that primarily affects prematurely born infants, particularly those with low birth weight and/or young gestational age. It is characterized by the abnormal growth and development of retinal blood vessels due to disturbances in the oxygen supply and metabolic demands during critical phases of fetal development.

The condition can be classified into various stages (1-5) based on its severity, with stages 4 and 5 being more severe forms that may lead to retinal detachment and blindness if left untreated. The pathogenesis of ROP involves an initial phase of vessel loss and regression in the central retina, followed by a secondary phase of abnormal neovascularization, which can cause fibrosis, traction, and ultimately, retinal detachment.

ROP is typically managed with a multidisciplinary approach involving ophthalmologists, neonatologists, and pediatricians. Treatment options include laser photocoagulation, cryotherapy, intravitreal anti-VEGF injections, or even surgical interventions to prevent retinal detachment and preserve vision. Regular screening examinations are crucial for early detection and timely management of ROP in at-risk infants.

I'm sorry for any confusion, but "Nigeria" is not a medical term. It is a country located in West Africa, and it is the most populous country in Africa. If you have any questions about medical conditions or terms, I would be happy to help clarify those for you.

Retinal rod photoreceptor cells are specialized neurons in the retina of the eye that are primarily responsible for vision in low light conditions. They contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a single photon of light. This triggers a cascade of biochemical reactions that ultimately leads to the generation of electrical signals, which are then transmitted to the brain via the optic nerve.

Rod cells do not provide color vision or fine detail, but they allow us to detect motion and see in dim light. They are more sensitive to light than cone cells, which are responsible for color vision and detailed sight in bright light conditions. Rod cells are concentrated at the outer edges of the retina, forming a crescent-shaped region called the peripheral retina, with fewer rod cells located in the central region of the retina known as the fovea.

Trichiasis is a medical condition where the eyelashes are abnormally positioned and grow inward, so that they rub against the cornea or the inner surface of the eyelid. This can cause irritation, discomfort, and potentially lead to corneal abrasions, scarring, or infection if left untreated. It is often caused by inflammation, injury, or an aging process that affects the eyelids. Treatment options include epilation (removal of the lashes), electrolysis, or surgery to reposition or remove the misdirected lashes and prevent recurrence.

Rural health is a branch of healthcare that focuses on the unique health challenges and needs of people living in rural areas. The World Health Organization (WHO) defines rural health as "the state of complete physical, mental and social well-being and not merely the absence of disease or infirmity, in the rural population."

Rural populations often face disparities in healthcare access and quality compared to their urban counterparts. Factors such as geographic isolation, poverty, lack of transportation, and a shortage of healthcare providers can contribute to these disparities. Rural health encompasses a broad range of services, including primary care, prevention, chronic disease management, mental health, oral health, and emergency medical services.

The goal of rural health is to improve the health outcomes of rural populations by addressing these unique challenges and providing high-quality, accessible healthcare services that meet their needs. This may involve innovative approaches such as telemedicine, mobile health clinics, and community-based programs to reach people in remote areas.

Special education is a type of education that is designed to meet the unique needs of students with disabilities. According to the Individuals with Disabilities Education Act (IDEA) in the United States, special education is defined as:

"Specially designed instruction, at no cost to the parents, to meet the unique needs of a child with a disability, including—

(A) Instruction conducted in the classroom, in the home, in hospitals and institutions, and in other settings; and

(B) Instruction in physical education."

Special education may include a variety of services, such as:

* Specially designed instruction to meet the unique needs of the child
* Related services, such as speech therapy, occupational therapy, or physical therapy
* Assistive technology devices and services
* Counseling and behavioral supports
* Transportation services

Special education is provided in a variety of settings, including regular classrooms, resource rooms, self-contained classrooms, and specialized schools. The goal of special education is to provide students with disabilities with the skills and knowledge they need to be successful in school and in life.

Ocular vision refers to the ability to process and interpret visual information that is received by the eyes. This includes the ability to see clearly and make sense of the shapes, colors, and movements of objects in the environment. The ocular system, which includes the eye and related structures such as the optic nerve and visual cortex of the brain, works together to enable vision.

There are several components of ocular vision, including:

* Visual acuity: the clarity or sharpness of vision
* Field of vision: the extent of the visual world that is visible at any given moment
* Color vision: the ability to distinguish different colors
* Depth perception: the ability to judge the distance of objects in three-dimensional space
* Contrast sensitivity: the ability to distinguish an object from its background based on differences in contrast

Disorders of ocular vision can include refractive errors such as nearsightedness or farsightedness, as well as more serious conditions such as cataracts, glaucoma, and macular degeneration. These conditions can affect one or more aspects of ocular vision and may require medical treatment to prevent further vision loss.

Cis-trans isomeres are molecules that have the same molecular formula and skeletal structure, but differ in the arrangement of their atoms around a double bond. In a cis isomer, the two larger groups or atoms are on the same side of the double bond, while in a trans isomer, they are on opposite sides.

Cis-trans isomerases are enzymes that catalyze the interconversion between cis and trans isomers of various molecules, such as fatty acids, steroids, and retinals. These enzymes play important roles in various biological processes, including membrane fluidity, vision, and the biosynthesis of hormones and other signaling molecules.

Examples of cis-trans isomerases include:

* Fatty acid desaturases, which introduce double bonds into fatty acids and can convert trans isomers to cis isomers
* Retinal isomerases, which interconvert the cis and trans isomers of retinal, a molecule involved in vision
* Steroid isomerases, which catalyze the interconversion of various steroids, including cholesterol and its derivatives.

A cartoon, in the context of medical definition, can refer to a simplified or exaggerated drawing or illustration that is used to explain complex medical concepts or procedures in a way that is easy for patients and their families to understand. These types of cartoons are often used in patient education materials, such as brochures, posters, and videos.

In addition, the term "cartoon" can also be used more broadly to refer to any humorous or satirical illustration that relates to medical topics or healthcare issues. These types of cartoons may appear in medical journals, newsletters, or other publications, and are often used to highlight problems within the healthcare system or to make light of certain aspects of medical practice.

Overall, the use of cartoons in a medical context is intended to help communicate important information in a way that is engaging, memorable, and accessible to a wide audience.

"Sex distribution" is a term used to describe the number of males and females in a study population or sample. It can be presented as a simple count, a percentage, or a ratio. This information is often used in research to identify any differences in health outcomes, disease prevalence, or response to treatment between males and females. Additionally, understanding sex distribution can help researchers ensure that their studies are representative of the general population and can inform the design of future studies.

The education of visually disabled refers to the specialized teaching and learning methods, materials, and environments designed to meet the unique needs and abilities of individuals with visual impairments. This includes those who are blind, have low vision, or have other visual disorders that impact their ability to access and process information in traditional educational settings.

The education of visually disabled may involve the use of assistive technologies such as screen readers, magnifiers, and Braille displays, as well as adaptive teaching strategies that emphasize tactile, auditory, and kinesthetic learning modalities. It also includes training in daily living skills, orientation and mobility, and social interaction to promote independence and self-advocacy.

The goal of the education of visually disabled is to provide students with equal access to educational opportunities and to help them develop the knowledge, skills, and attitudes necessary for success in academic, vocational, and personal pursuits.

Photoreceptor cells in vertebrates are specialized types of neurons located in the retina of the eye that are responsible for converting light stimuli into electrical signals. These cells are primarily responsible for the initial process of vision and have two main types: rods and cones.

Rods are more numerous and are responsible for low-light vision or scotopic vision, enabling us to see in dimly lit conditions. They do not contribute to color vision but provide information about the shape and movement of objects.

Cones, on the other hand, are less numerous and are responsible for color vision and high-acuity vision or photopic vision. There are three types of cones, each sensitive to different wavelengths of light: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red, respectively. The combination of signals from these three types of cones allows us to perceive a wide range of colors.

Both rods and cones contain photopigments that consist of a protein called opsin and a light-sensitive chromophore called retinal. When light hits the photopigment, it triggers a series of chemical reactions that ultimately lead to the generation of an electrical signal that is transmitted to the brain via the optic nerve. This process enables us to see and perceive our visual world.

I must clarify that the term "pedigree" is not typically used in medical definitions. Instead, it is often employed in genetics and breeding, where it refers to the recorded ancestry of an individual or a family, tracing the inheritance of specific traits or diseases. In human genetics, a pedigree can help illustrate the pattern of genetic inheritance in families over multiple generations. However, it is not a medical term with a specific clinical definition.

Vision screening is a quick and cost-effective method used to identify individuals who are at risk of vision problems or eye diseases. It is not a comprehensive eye examination, but rather an initial evaluation that helps to determine if a further, more in-depth examination by an eye care professional is needed. Vision screenings typically involve tests for visual acuity, distance and near vision, color perception, depth perception, and alignment of the eyes. The goal of vision screening is to detect potential vision issues early on, so that they can be treated promptly and effectively, thereby preventing or minimizing any negative impact on a person's overall vision and quality of life.

Myopia, also known as nearsightedness, is a common refractive error of the eye. It occurs when the eye is either too long or the cornea (the clear front part of the eye) is too curved. As a result, light rays focus in front of the retina instead of directly on it, causing distant objects to appear blurry while close objects remain clear.

Myopia typically develops during childhood and can progress gradually or rapidly until early adulthood. It can be corrected with glasses, contact lenses, or refractive surgery such as LASIK. Regular eye examinations are essential for people with myopia to monitor any changes in their prescription and ensure proper correction.

While myopia is generally not a serious condition, high levels of nearsightedness can increase the risk of certain eye diseases, including cataracts, glaucoma, retinal detachment, and myopic degeneration. Therefore, it's crucial to manage myopia effectively and maintain regular follow-ups with an eye care professional.

Uveitis is the inflammation of the uvea, the middle layer of the eye between the retina and the white of the eye (sclera). The uvea consists of the iris, ciliary body, and choroid. Uveitis can cause redness, pain, and vision loss. It can be caused by various systemic diseases, infections, or trauma. Depending on the part of the uvea that's affected, uveitis can be classified as anterior (iritis), intermediate (cyclitis), posterior (choroiditis), or pan-uveitis (affecting all layers). Treatment typically includes corticosteroids and other immunosuppressive drugs to control inflammation.

Eyeglasses are a medical device used to correct vision problems. Also known as spectacles, they consist of frames that hold one or more lenses through which a person looks to see clearly. The lenses may be made of glass or plastic and are designed to compensate for various visual impairments such as nearsightedness, farsightedness, astigmatism, or presbyopia. Eyeglasses can be custom-made to fit an individual's face and prescription, and they come in a variety of styles, colors, and materials. Some people wear eyeglasses all the time, while others may only need to wear them for certain activities such as reading or driving.

Rhodopsin, also known as visual purple, is a light-sensitive pigment found in the rods of the vertebrate retina. It is a complex protein molecule made up of two major components: an opsin protein and retinal, a form of vitamin A. When light hits the retinal in rhodopsin, it changes shape, which initiates a series of chemical reactions leading to the activation of the visual pathway and ultimately results in vision. This process is known as phototransduction. Rhodopsin plays a crucial role in low-light vision or scotopic vision.

I'm sorry for any confusion, but "Oman" is not a medical term or concept. It is the name of a country, which is located on the southeastern coast of the Arabian Peninsula in Western Asia. If you have any questions related to medicine or healthcare, I would be happy to try and help answer those for you!

"Fundus Oculi" is a medical term that refers to the back part of the interior of the eye, including the optic disc, macula, fovea, retinal vasculature, and peripheral retina. It is the area where light is focused and then transmitted to the brain via the optic nerve, forming visual images. Examinations of the fundus oculi are crucial for detecting various eye conditions such as diabetic retinopathy, macular degeneration, glaucoma, and other retinal diseases. The examination is typically performed using an ophthalmoscope or a specialized camera called a retinal camera.

Medical Definition of Vitamin A:

Vitamin A is a fat-soluble vitamin that is essential for normal vision, immune function, and cell growth. It is also an antioxidant that helps protect the body's cells from damage caused by free radicals. Vitamin A can be found in two main forms: preformed vitamin A, which is found in animal products such as dairy, fish, and meat, particularly liver; and provitamin A carotenoids, which are found in plant-based foods such as fruits, vegetables, and vegetable oils.

The most active form of vitamin A is retinoic acid, which plays a critical role in the development and maintenance of the heart, lungs, kidneys, and other organs. Vitamin A deficiency can lead to night blindness, dry skin, and increased susceptibility to infections. Chronic vitamin A toxicity can cause nausea, dizziness, headaches, coma, and even death.

Sensory aids are devices or equipment that are used to improve or compensate for impaired sensory functions such as hearing, vision, or touch. They are designed to help individuals with disabilities or impairments to better interact with their environment and perform daily activities. Here are some examples:

1. Hearing aids - electronic devices worn in or behind the ear that amplify sounds for people with hearing loss.
2. Cochlear implants - surgically implanted devices that provide sound sensations to individuals with severe to profound hearing loss.
3. Visual aids - devices used to improve vision, such as eyeglasses, contact lenses, magnifiers, or telescopic lenses.
4. Low vision devices - specialized equipment for people with significant visual impairment, including large print books, talking watches, and screen readers.
5. Tactile aids - devices that provide tactile feedback to individuals with visual or hearing impairments, such as Braille displays or vibrating pagers.

Overall, sensory aids play an essential role in enhancing the quality of life for people with sensory impairments by improving their ability to communicate, access information, and navigate their environment.

I'm sorry for any confusion, but "Tonga" is not a medical term. It is a country in the South Pacific Ocean, known officially as the Kingdom of Tonga. If you have any medical terms or concepts that you would like me to define or explain, I would be happy to help!

Vision tests are a series of procedures used to assess various aspects of the visual system, including visual acuity, accommodation, convergence, divergence, stereopsis, color vision, and peripheral vision. These tests help healthcare professionals diagnose and manage vision disorders, such as nearsightedness, farsightedness, astigmatism, amblyopia, strabismus, and eye diseases like glaucoma, cataracts, and macular degeneration. Common vision tests include:

1. Visual acuity test (Snellen chart or letter chart): Measures the sharpness of a person's vision at different distances.
2. Refraction test: Determines the correct lens prescription for glasses or contact lenses by assessing how light is bent as it passes through the eye.
3. Color vision test: Evaluates the ability to distinguish between different colors and color combinations, often using pseudoisochromatic plates or Ishihara tests.
4. Stereopsis test: Assesses depth perception and binocular vision by presenting separate images to each eye that, when combined, create a three-dimensional effect.
5. Cover test: Examines eye alignment and the presence of strabismus (crossed eyes or turned eyes) by covering and uncovering each eye while observing eye movements.
6. Ocular motility test: Assesses the ability to move the eyes in various directions and coordinate both eyes during tracking and convergence/divergence movements.
7. Accommodation test: Evaluates the ability to focus on objects at different distances by using lenses, prisms, or dynamic retinoscopy.
8. Pupillary response test: Examines the size and reaction of the pupils to light and near objects.
9. Visual field test: Measures the peripheral (side) vision using automated perimetry or manual confrontation techniques.
10. Slit-lamp examination: Inspects the structures of the front part of the eye, such as the cornea, iris, lens, and anterior chamber, using a specialized microscope.

These tests are typically performed by optometrists, ophthalmologists, or other vision care professionals during routine eye examinations or when visual symptoms are present.

Onchocerca is a genus of filarial nematode worms that are the causative agents of onchocerciasis, also known as river blindness. The most common species to infect humans is Onchocerca volvulus. These parasites are transmitted through the bite of infected blackflies (Simulium spp.) that breed in fast-flowing rivers and streams.

The adult female worms live in nodules beneath the skin, while the microfilariae, which are released by the females, migrate throughout various tissues, including the eyes, where they can cause inflammation and scarring, potentially leading to blindness if left untreated. The infection is primarily found in Africa, with some foci in Central and South America. Onchocerciasis is considered a neglected tropical disease by the World Health Organization (WHO).

"World Health" is not a term that has a specific medical definition. However, it is often used in the context of global health, which can be defined as:

"The area of study, research and practice that places a priority on improving health and achieving equity in health for all people worldwide. It emphasizes trans-national health issues, determinants, and solutions; involves many disciplines within and beyond the health sciences and engages stakeholders from across sectors and societies." (World Health Organization)

Therefore, "world health" could refer to the overall health status and health challenges faced by populations around the world. It encompasses a broad range of factors that affect the health of individuals and communities, including social, economic, environmental, and political determinants. The World Health Organization (WHO) plays a key role in monitoring and promoting global health, setting international standards and guidelines, and coordinating responses to global health emergencies.

Health surveys are research studies that collect data from a sample population to describe the current health status, health behaviors, and healthcare utilization of a particular group or community. These surveys may include questions about various aspects of health such as physical health, mental health, chronic conditions, lifestyle habits, access to healthcare services, and demographic information. The data collected from health surveys can be used to monitor trends in health over time, identify disparities in health outcomes, develop and evaluate public health programs and policies, and inform resource allocation decisions. Examples of national health surveys include the National Health Interview Survey (NHIS) and the Behavioral Risk Factor Surveillance System (BRFSS).

"Field Dependence-Independence" is not a term used in medical definitions. However, it is a concept in the field of psychology, particularly in the area of perception and cognition.

Field dependence-independence is a personality trait that refers to an individual's ability to perceive and process information independently from the surrounding environment or "field." It is a measure of how much an individual's cognitive style is influenced by contextual cues and stimuli in their environment.

Individuals who are field-dependent tend to be heavily influenced by their surroundings and have difficulty separating relevant from irrelevant information. They may have trouble focusing on specific details when there are distractions or competing stimuli in the environment. In contrast, individuals who are field-independent are less influenced by their surroundings and can focus more easily on specific details and tasks, even in the presence of distractions.

Field dependence-independence is often assessed using psychometric tests such as the Embedded Figures Test (EFT) or the Rod and Frame Test (RFT). These tests measure an individual's ability to perceive and process information independently from their environment, providing insights into their cognitive style and problem-solving abilities.

I'm sorry for any confusion, but "Sudan" is not a medical term. It is a country located in Northeast Africa, known as the Sudan or Sudan proper, and the southern region that seceded to become South Sudan in 2011. If you have any medical terms you would like me to define, please let me know!

Color perception tests are a type of examination used to evaluate an individual's ability to perceive and distinguish different colors. These tests typically consist of a series of plates or images that contain various patterns or shapes displayed in different colors. The person being tested is then asked to identify or match the colors based on specific instructions.

There are several types of color perception tests, including:

1. Ishihara Test: This is a commonly used test for red-green color deficiency. It consists of a series of plates with circles made up of dots in different sizes and colors. Within these circles, there may be a number or symbol visible only to those with normal color vision or to those with specific types of color blindness.
2. Farnsworth D-15 Test: This test measures an individual's ability to arrange colored caps in a specific order based on their hue. It is often used to diagnose and monitor the progression of color vision deficiencies.
3. Hardy-Rand-Rittler (HRR) Test: This is another type of color arrangement test that measures an individual's ability to distinguish between different colors based on their hue, saturation, and brightness.
4. Color Discrimination Tests: These tests measure an individual's ability to distinguish between two similar colors that are presented side by side or in close proximity.
5. Anomaloscope Test: This is a more sophisticated test that measures the degree of color vision deficiency by asking the person to match the brightness and hue of two lights.

Color perception tests are often used in occupational settings, such as aviation, military, and manufacturing, where color discrimination is critical for safety and performance. They may also be used in educational and clinical settings to diagnose and monitor color vision deficiencies.

... and cortical visual impairment (CVI), which refers to the partial loss of vision caused by cortical damage, ... Cortical blindness can be acquired or congenital, and may also be transient in certain instances. Acquired cortical blindness ... Fundoscopy should be normal in cases of cortical blindness. Cortical blindness can be associated with visual hallucinations, ... The development of cortical blindness into the milder cortical visual impairment is a more likely outcome. Furthermore, some ...
Visual deficits, such as agnosia, prosopagnosia or cortical blindness (with bilateral infarcts) may be a product of ischemic ... Peripheral Territory Lesions Contralateral homonymous hemianopsia cortical blindness with bilateral involvement of the ... Stroke syndromes: Cortical blindness. [Internet]. [updated 1999 July; cited 2011 May 13]. Retrieved from http://www. ...
Cortical blindness Roman-Lantzy, Christine (2019). Cortical Visual Impairment: Advanced Principles. Louisville, Ky: AFB Press. ... CVI is also sometimes known as cortical blindness, although most people with CVI are not totally blind. The term neurological ... Cortical Blindness)". The Marshall Cavendish Encyclopedia of Personal Relationships.[page needed] "What is CVI? Why your child/ ... covers both CVI and total cortical blindness. Delayed visual maturation, another form of NVI, is similar to CVI, except the ...
diabetes, etc.) Brain damage - cortical blindness is a known but uncommon complication of acute hypoxic damage to the cerebral ... Kam, C.A.; Yoong, Florence F.Y.; Ganendran, A. (1978). "Cortical blindness following hypoxia during cardiac arrest". Anaesth. ...
Heywood, C.A.; Kentridge, R.W.; Cowey, A. (September 1998). "Cortical Color Blindness is Not "Blindsight for Color"". ... Color blindness (or color vision deficiency) is a defect of normal color vision. Because color blindness is a symptom of ... color blindness causes difficulty in all four kinds of color tasks. However, cerebral color blindness may cause issues only in ... Sometimes, color blindness derived from brain damage (e.g. cerebral achromatopsia can affect the other color tasks while ...
... cortical blindness, awareness or denial of blindness; tactile naming, achromatopia (color blindness), failure to see to-and-fro ... The cortical branches are: Anterior temporal, distributed to the uncus and the anterior part of the fusiform gyrus Posterior ... cortical segment Within the sulci of the occipital lobe The branches of the posterior cerebral artery are divided into two sets ... ganglionic and cortical. The following are central branches of the PCA, also known as perforating branches: Thalamoperforating ...
Recovery from blindness See for example: Uri Polat (2008). "Restoration of underdeveloped cortical functions: Evidence from ...
Symptoms of cortical blindness vary greatly across individuals and may be more severe in periods of exhaustion or stress. It is ... Blindness-presenting visual acuity worse than 1/60 with light perception Category 5: Blindness-irreversible blindness with no ... Cortical blindness results from injuries to the occipital lobe of the brain that prevent the brain from correctly receiving or ... Blindness at Curlie Chisholm, Hugh, ed. (1911). "Blindness" . Encyclopædia Britannica (11th ed.). Cambridge University Press. ...
Bilateral lesions of the occipital lobe can lead to cortical blindness (see Anton's syndrome). The two occipital lobes are the ... Damage to the primary visual areas of the occipital lobe can cause partial or complete blindness. The occipital lobe is divided ... Functional neuroimaging reveals similar patterns of response in cortical tissue of the lobes when the retinal fields are ... can cause blindness due to the holes in the visual map on the surface of the visual cortex that resulted from the lesions. ...
Alterations in vision (vision blurring, hemivisual field defects, color blindness, cortical blindness) are common. They occur ... Brain ventricles are compressed, cortical gyri flattened.[citation needed] Diagnostic methods for hypertensive encephalopathy ...
Siu T. L.; Morley J. W. (2008). "Suppression of visual cortical evoked responses following deprivation of pattern vision in ... "Recovery from Early Blindness". Retrieved 2010-05-04. "recovery from blindness: Information from Answers.com". Answers.com. ... Recovery from blindness is the phenomenon of a blind person gaining the ability to see, usually as a result of medical ... May's early blindness benefited him so far; he developed very precise senses of hearing and touch. In 2006, journalist Robert ...
Other cerebral signs that may precede the convulsion include nausea, vomiting, headaches, and cortical blindness. If the ... or cortical blindness, which affects the vision from both eyes. There are also potential complications in the lungs. The woman ... OCLC 727346377.{{cite book}}: CS1 maint: others (link) Cunningham FG, Fernandez CO, Hernandez C (April 1995). "Blindness ... one-sided blindness (either temporary due to amaurosis fugax or potentially permanent due to retinal detachment), ...
"Blunt cervical spine trauma as a cause of spinal cord injury and delayed cortical blindness". Spinal Cord. 45 (10): 687-689. ...
... or cortical blindness, results from much larger lesions in the occipital cortex. Cortical blindness appears as a complete loss ... Throughout his research he discovered that cortical lesions in the visual areas lead to blindness. He called blindness ... The dogs normally recovered from psychic blindness in 4 to 6 weeks and did appear to relearn faster than they first learned ... While suffering from psychic blindness, dogs were able to navigate effectively but showed no sign that they recognized what the ...
It is not uncommon for the erroneous diagnoses of malingering or cortical blindness to be made. If possible, an urgent neuro- ... To prevent impending blindness, it is urgent to rule out giant cell arteritis when a patient over 50 presents with sudden ... Restricted blood flow can lead to permanent damage to the optic nerve and result in blindness (often in both eyes). For ... Pazos GA, Leonard DW, Blice J, Thompson DH (1999). "Blindness after bilateral neck dissection: case report and review". ...
Achromatopsia Cortical blindness Color blindness Ishihara color test Jaeger W, Krastel H, Braun S (December 1988). "[Cerebral ... A case of cerebral achromatopsia, acquired after a cortical lesion, was described by Dr. Verrey in 1888. but the evidence was ... Cerebral achromatopsia is a type of color-blindness caused by damage to the cerebral cortex of the brain, rather than ... It is a consequence of cortical damage that arises through ischemia or infarction of a specific area in the ventral ...
Color blindness, a color vision deficiency. Cortical blindness, a loss of vision caused by damage to the visual area in the ... Inattentional blindness or perceptual blindness, failing to notice some stimulus that is in plain sight. Motion blindness, a ... Change blindness, the inability to detect some changes in busy scenes. Choice blindness, a result in a perception experiment by ... Flash blindness, a visual impairment following exposure to a light flash. Hysterical blindness (nowadays known as conversion ...
Saigal G, Bhatia R, Bhatia S, Wakhloo AK (February 2004). "MR findings of cortical blindness following cerebral angiography: is ... of the cases experience cortical blindness from 3 minutes to 12 hours after the procedure. It is a condition where those ...
... and cortical blindness. It is caused by recessive mutations in D2HGDH (type I) or by dominant gain-of-function mutations in ...
"A 3.1-Mb microdeletion of 3p21.31 associated with cortical blindness, cleft lip, CNS abnormalities, and developmental delay". ...
Cortical blindness refers to any partial or complete visual deficit that is caused by damage to the visual cortex in the ... Bilateral lesions can cause complete cortical blindness and can sometimes be accompanied by a condition called Anton-Babinski ... and hyperammonemia can cause cortical blindness. Occipital cortex lesions tend to cause homonymous hemianopias of variable size ... Lesions involving the whole optic nerve cause complete blindness on the affected side, that means damage at the right optic ...
... normal outcome in a patient with late diagnosis after prolonged status epilepticus causing cortical blindness". Neuropediatrics ...
1899, S. 86 - On the self-perception of focal lesions in patients with cortical blindness and cortical deafness. Über den ...
This cut off oxygen to her brain, resulting in a brain stem contusion, cervical cord injury, and cortical blindness. She was ...
... and/or cortical visual impairment). In rare cases, decreased visual acuity(blindness) can occur. dental enamel hypoplasia/ ... Severe cortical involvement is uncommon. SBE is a chronic state of mild bilirubin-induced neurological dysfunction (BIND). ...
Yusof utilized the metaphor of Anton-Babinski syndrome (cortical blindness), emptying the city of Kuala Lumpur of people ...
... and autobiographical amnesia following recovery from cortical blindness: case M.H.". Neuropsychologia. 31 (6): 571-589. doi: ...
Cortical area Cortical blindness Feature integration theory List of regions in the human brain Retinotopy Visual processing ... MT is connected to a wide array of cortical and subcortical brain areas. Its input comes from visual cortical areas V1, V2 and ... the influence of higher-tier cortical areas on lower-tier cortical areas) and lateral connections from pyramidal neurons (Hupe ... In mammals, it is located in the posterior pole of the occipital lobe and is the simplest, earliest cortical visual area. It is ...
Dandolo had cortical blindness as a result of a severe blow to the back of the head received sometime between 1174 and 1176. ... This piece of primary evidence seems to support Madden's theory that Dandolo's blindness was cortical, since his eyes appeared ... Dandolo's blindness appears to have been total. Geoffrey de Villehardouin, whom Dandolo accompanied on the Fourth Crusade, ...
He would later be diagnosed to be suffering from epilepsy and cortical blindness, though the apparent life-threatening event ...
Cortical blindness and cortical visual impairment (CVI), which refers to the partial loss of vision caused by cortical damage, ... Cortical blindness can be acquired or congenital, and may also be transient in certain instances. Acquired cortical blindness ... Fundoscopy should be normal in cases of cortical blindness. Cortical blindness can be associated with visual hallucinations, ... The development of cortical blindness into the milder cortical visual impairment is a more likely outcome. Furthermore, some ...
Cortical" by people in this website by year, and whether "Blindness, Cortical" was a major or minor topic of these publications ... "Blindness, Cortical" is a descriptor in the National Library of Medicines controlled vocabulary thesaurus, MeSH (Medical ... MR findings of cortical blindness following cerebral angiography: is this entity related to posterior reversible ... Anton syndrome is characterized by the psychic denial of true, organic cortical blindness. (Adams et al., Principles of ...
This work is being financed by the FCT project with the reference PTDC/EGE-OGE/7995/2020 ...
CASE REPORT: We report a case of a 14-year-old African boy from Nigeria with bilateral cortical blindness caused by NCC due to ... In this report, we present a case of bilateral cortical blindness due to NCC in a 14-year-old African boy from Nigeria. The ... In addition, there have been reports of very rare cases of bilateral cortical blindness caused by helminths in children. It is ... The remaining lesions were caused by chiasmal and retrochiasmal lesions [8]. The etiology of cortical blindness due to ...
Cortical blindness is a "no treatment" diagnosis. The proper term is cerebral or cortical visual impairment (CVI). The ... Cortical Blindness is a negative cue that each and every doctor sees, anytime your child is ill. From a parents point of view ... Cortical Blindness occurs in babies with birth asphyxia, more in full-term than preterm infants. In children, it is an outdated ... The diagnosis of cortical blindness is initially a clinical diagnosis made by the presence of roving nystagmus. The baby seems ...
Blindness: May be cortical [3] or retinal. * Dyspnea. * Edema: Sudden increase in edema or facial edema ...
Optic nerve involvement (may lead to blindness) Seizure symptoms include the following:. * Seizures are most common during ...
... cortical blindness, brain atrophy. 1993. Michigan. 9 mo. Male. Unknown. Unknown. Serologic. Neurologic deficits, cortical ... Neurologic deficits, cortical blindness, seizures. 2004‡. Louisiana. 4 y. Male. 1,920 (12). 954 (55). Serologic. Full recovery ... Neurologic deficits, blindness, seizures, brain atrophy. 1996. Illinois. 6 y. Male. 605 (5). 2 (,1). Serologic. Neurologic ... Neurologic deficits, blindness, generalized spasticity. 2000. California. 17 y. Male. 2,385 (15). 7 (37). Brain biopsy, ...
Cortical Blindness (Anton Syndrome);. Gerstmann Syndrome;. Lateral Medullary Syndrome (Wallenberg Syndrome);. Lateral Pontine ...
3 = Bilateral hemianopia (blind including cortical blindness).. 4: Facial Palsy Instructions Ask or use pantomime to encourage ... If there is unilateral blindness or enucleation, visual fields in the remaining eye are scored. Score 1 only if a clear-cut ... In case of blindness, test by having the patient touch nose from extended arm position. ... Patients with ocular trauma, bandages, pre-existing blindness, or other disorder of visual acuity or fields should be tested ...
4 cases with transient cortical blindness (0.10%) and 2 cases of transient global amnesia (0.05%). The permanent ones were: 1 ...
Cortical visual impairment is when children show abnormal visual responses that arent caused by the eyes themselves. Learn ... It is now widely accepted that "cortical blindness" is not an appropriate diagnostic term for children with early, acquired ... Cortical Visual Impairment , Symptoms & Causes. Cortical visual impairment. Presently, cortical visual impairment (CVI) is the ... Thus, "cerebral visual impairment" is preferred to "cortical blindness.". Common causes CVI in infants and young children ...
... and blindness can have many causes. If you lose vision, you cant get it back. But there are ways to manage; learn how. ... Cortical Visual Impairment (American Association for Pediatric Ophthalmology and Strabismus) * Delayed Visual Maturation ( ... ClinicalTrials.gov: Blindness (National Institutes of Health) * ClinicalTrials.gov: Vision Disorders (National Institutes of ... The leading causes of low vision and blindness in the United States are age-related eye diseases: macular degeneration, ...
Seizures, Cortical Blindness, Microcephaly Syndrome (SCBMS) approved 616632. Licence Committee minutes- PGD ...
Ishai, A. et al (2005). Face perception is mediated by a distributed cortical network Brain Res. Bull. 67: 87-93 (2005). [PDF] ... The form of face blindness is congenital: those who inherit a genetic mutation are born with an impaired ability to recognize ... Also known as face blindness, prosopagnosia is associated with damage to specific parts of the temporal lobes. But there are ...
... inattention blindness’. Scientists already know that performing a task involving high information load - a ‘high load ... Study unveils the engagement of different cortical networks while humans are unconscious. Nov 27, 2023 ... Inattention blindness due to brain load. by University College London "When we perform a task which demands processing a high ... But it also leads to inattentional blindness, where we cant perceive unattended stimuli that are not part of the task even in ...
Visual recovery in cortical blindness is limited by high internal noise.﻽. Cavanaugh MR, Zhang R, Melnick MD, Das A, Roberts M ... Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness.﻽. Cavanaugh MR, Huxlin KR ... Author response: Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness.﻽. Huxlin ...
Internal hydrocephalus: state after implantation of a VP-shunt; epilepsy; spastic quadriparesis; cortical blindness; delay in ...
Cross References Agnosia; Alexia; Cortical blindness; Optic aphasia; Prosopagnosia; RiddochпїЅs phenomenon; Simultanagnosia; ... Constitutes a medical emergency because blindness might physician visits yearly (Schappert, 1995); return visits ensue all of a ...
RIT researcher receives award to advance study of cortical blindness Gabriel Diaz, associate professor in the Chester F. ... Cortical blindness affects nearly half a million stroke patients in the United States each year. ... and his team are aiming to understand the effects of cortical blindness on the processing of visual information used to guide ...
Cortical blindness during chemotherapy: clinical, CT and MR correlations. J Comput Assist Tomogr 1990;14:262-266. ... The development of cortical laminar necrosis with cortical hyperintensity and diffuse cortical atrophy on T1-weighted images ... Transient cortical blindness secondary to vincristine therapy in childhood malignancies. Cancer 1981;47:37-40. ... In the few cases of cortical blindness related to vincristine reported in the literature, CT findings were normal and no MR ...
Both serous retinal detachment and cortical blindness may occur. C. Pulmonary System. Pulmonary edema may occur with severe ... T2-weighed MRI scans show high signal in the cortical and subcortical white matter. Most of the abnormalities lie in the ...
Mean cortical thickness analysis revealed a significant increase in values in the advanced glaucoma group in the right Brodmann ... Volume and cortical thickness analyses were performed using the open-source automated software package FreeSurfer. Results: ... Glaucoma is the second-leading cause of blindness worldwide and the most frequent cause of irreversible blindness worldwide [2, ... Table 2. Mean cortical thickness results in selected visual regions based on Destrieux cortical parcellation atlas in control ...
Focal neurologic signs include aphasia, hemiparesis, ataxia, cortical blindness, limb apraxia, brainstem symptoms and, less ... The demyelinating plaques involve subcortical U fibers but tend to spare the cortical ribbons and deep gray matter structures; ... Mild cortical atrophy may be seen on biopsy specimens. Immunohistochemistry or in situ hybridization is the best method to ... such foci may be seen in the cortical gray matter. Foci may become confluent (see the images below). Oligodendrocytes at the ...
Some cases of strokes and seizures were also preceded by visual disturbances (blurred vision, and transient cortical blindness ...
Tragically, the baby has cortical blindness, seizures, and significant developmental delays. This birth injury claim settled ... resulting in cerebral palsy and cortical blindness. The mother and father sued the hospital, and the nurse midwife and her ...
Three children with malignancies developed severe neurotoxicity, including transient cortical blindness, following chemotherapy ... Three children with malignancies developed severe neurotoxicity, including transient cortical blindness, following chemotherapy ... Byrd RL, Rohrbaugh TM, Raney RB Jr, Norris DG. Transient cortical blindness secondary to vincristine therapy in childhood ... Byrd RL, Rohrbaugh TM, Raney RB Jr, Norris DG. Transient cortical blindness secondary to vincristine therapy in childhood ...
Specific events reported include, but are not limited to, spinal cord infarction, paraplegia, quadriplegia, cortical blindness ... Ophthalmic Exophthalmos, glaucoma, increased intraocular pressure, posterior subcapsular cataracts, rare instances of blindness ...
hearing loss, visual impairment, blindness, learning difficulties, epilepsy. *most infected women have symptoms similar to mono ...
  • The adult male donor had a history of cerebral palsy, seizures, and blindness. (cdc.gov)
  • 6 Despite its name, the disease is not restricted to cerebral white matter as the presentation may be with cortical deficits such as dysphasia, cortical blindness, or seizures. (bmj.com)
  • These two and nine other reported patients share the following features: ragged red fibers evident on muscle biopsy, normal early development, short stature, seizures, and hemiparesis, hemianopia, or cortical blindness. (nih.gov)
  • According to the boy's mother, symptoms began with headaches, vomiting, fatigue, visual loss, and fever (40.0 °C). Clinical investigations led to a diagnosis of cortical blindness and encephalitis due to NCC. (researchsquare.com)
  • A thorough neurological examination with CSF analysis and imaging studies was conducted, and a diagnosis of cortical blindness and encephalitis due to NCC was made. (researchsquare.com)
  • The diagnosis of cortical blindness is initially a clinical diagnosis made by the presence of roving nystagmus. (karenpapemd.com)
  • The diagnosis of cortical blindness, along with its diagnostic code, is put on the baby's chart. (karenpapemd.com)
  • At the parent meeting, I saw several children who have carried the diagnosis of cortical blindness that were perfectly capable of fixing and following, to some extent, objects put within their line of sight. (karenpapemd.com)
  • Once you get an ophthalmologist to agree that the child has some sight, then parents should get the diagnosis of cortical blindness off their child's medical record and the more correct CVI diagnosis added. (karenpapemd.com)
  • Acquired cortical blindness is most often caused by loss of blood flow to the occipital cortex from either unilateral or bilateral posterior cerebral artery blockage (ischemic stroke) and by cardiac surgery. (wikipedia.org)
  • In addition, there have been reports of very rare cases of bilateral cortical blindness caused by helminths in children. (researchsquare.com)
  • We report a case of a 14-year-old African boy from Nigeria with bilateral cortical blindness caused by NCC due to Taenia solium . (researchsquare.com)
  • The term "cortical" is misleading because the visual impairment is due to abnormality of bilateral, post-chiahydrocephalus shunt failure, se smal visual pathways, including damage to cortical (gray matter), subcortical (white matter), or both. (childrenshospital.org)
  • 3 = Bilateral hemianopia (blind including cortical blindness) stimulation is performed at this point. (medscape.com)
  • My research involves investigation of conditions which cause monocular or bilateral blindness in infants and children. (ski.org)
  • Thus, "cerebral visual impairment" is preferred to "cortical blindness. (childrenshospital.org)
  • Less than 20% of children with CVI (Cortical/Cerebral Visual Impairment) have been diagnosed with this leading cause of childhood blindness, according to new research conducted by the CVI Center at Perkins School for the Blind with analysis from McKinsey & Company. (perkins.org)
  • Cortical blindness can be acquired or congenital, and may also be transient in certain instances. (wikipedia.org)
  • citation needed] The most common symptoms of acquired and transient cortical blindness include: A complete loss of visual sensation and of vision Preservation/sparing of the abilities to perceive light and/or moving, but not static objects (Riddoch syndrome) A lack of visual fixation and tracking Denial of visual loss (Anton-Babinski syndrome) Visual hallucinations Macular sparing, in which vision in the fovea is spared from the blindness. (wikipedia.org)
  • Furthermore, some patients regain vision completely, as is the case with transient cortical blindness associated with eclampsia and the side effects of certain anti-epilepsy drugs. (wikipedia.org)
  • Congenital cortical blindness is most often caused by perinatal ischemic stroke, encephalitis, and meningitis. (wikipedia.org)
  • The form of face blindness is congenital: those who inherit a genetic mutation are born with an impaired ability to recognize faces. (scienceblogs.com)
  • The NEI Small Business program funds clinical studies developing AI and telemedicine imaging tools that can provide early detection and prompt diagnostics for glaucoma, diabetic retinopathy (DR), and retinopathy of prematurity (ROP), a significant cause of blindness for very low birthweight premature infants. (nih.gov)
  • The research includes basic and clinical studies of retinopathy of prematurity and cortical visual impairment, the 2 leading causes of blindness in children in the United States. (ski.org)
  • For these reasons, the first FDA-approved gene therapy treats a form of childhood blindness caused by a mutation in a gene discovered at NEI. (nih.gov)
  • What are the symptoms of cortical visual impairment? (childrenshospital.org)
  • Summary: We report three patients in whom neurologic symptoms and cortical laminar necrosis developed after immunosuppressive treatment (cyclosporin A and FK 506) and polychemotherapy (vincristine and methotrexate). (ajnr.org)
  • One diagnostic marker of this distinction is that the pupils of individuals with cortical blindness will respond to light whereas those of individuals with ocular visual impairment will not. (wikipedia.org)
  • Therefore, one diagnostic test for cortical blindness is to first objectively verify the optic nerves and the non-cortical functions of the eyes are functioning normally. (wikipedia.org)
  • It is now widely accepted that "cortical blindness" is not an appropriate diagnostic term for children with early, acquired visual impairment due to non-ocular causes. (childrenshospital.org)
  • This portable system based on AI and virtual reality can improve diagnostic testing for glaucoma, a leading cause of blindness in African Americans and Hispanics. (nih.gov)
  • Initial neuroradiologic studies showed cortical and white matter involvement. (ajnr.org)
  • Cortical involvement may also be evident on MRI and in the neuropathological findings. (bmj.com)
  • In most cases, the complete loss of vision is not permanent and the patient may recover some of their vision (cortical visual impairment). (wikipedia.org)
  • Cortical blindness and cortical visual impairment (CVI), which refers to the partial loss of vision caused by cortical damage, are both classified as subsets of neurological visual impairment (NVI). (wikipedia.org)
  • NVI and its three subtypes-cortical blindness, cortical visual impairment, and delayed visual maturation-must be distinguished from ocular visual impairment in terms of their different causes and structural foci, the brain and the eye respectively. (wikipedia.org)
  • Cortical blindness can be associated with visual hallucinations, denial of visual loss (Anton-Babinski syndrome), and the ability to perceive moving but not static objects (Riddoch syndrome). (wikipedia.org)
  • The development of cortical blindness into the milder cortical visual impairment is a more likely outcome. (wikipedia.org)
  • The correct term is cerebral or cortical visual impairment. (karenpapemd.com)
  • However, the adult visual cortex represents approximately 40% of our cortical real estate. (karenpapemd.com)
  • Patients with ocular trauma, bandages, pre-existing blindness, or other disorder of visual acuity or fields should be tested with reflexive movements, and a choice made by the investigator. (nih.gov)
  • Cortical Visual Impairment (CVI) is diagnosed when children show abnormal visual responses that aren't caused by the eyes themselves. (childrenshospital.org)
  • Presently, cortical visual impairment (CVI) is the most common cause of permanent visual impairment in children (1-3). (childrenshospital.org)
  • Author response: Visual discrimination training improves Humphrey perimetry in chronic cortically induced blindness. (rochester.edu)
  • Visual recovery in cortical blindness is limited by high internal noise. (rochester.edu)
  • Patients with ocular trauma, bandages, pre-existing blindness or other 2 = Forced deviation, or total gaze paresis not overcome by the disorder of visual acuity or fields should be tested with reflexive oculocephalic maneuver. (medscape.com)
  • If there is unilateral ______ blindness or enucleation, visual fields in the remaining eye are scored. (medscape.com)
  • To this aim, through electrophysiology in cats, we explored that visual neurons, throughout the cortical column, have a tendency to alter their inherent properties even when presented a non-visual stimulus. (intechopen.com)
  • Follow-up studies showed cortical hyperintense lesions on T1-weighted MR images, consistent with cortical laminar necrosis. (ajnr.org)
  • Rarely, a patient with acquired cortical blindness may have little or no insight that they have lost vision, a phenomenon known as Anton-Babinski syndrome. (wikipedia.org)
  • Anton syndrome is characterized by the psychic denial of true, organic cortical blindness. (umassmed.edu)
  • Cortical Blindness occurs in babies with birth asphyxia, more in full-term than preterm infants. (karenpapemd.com)
  • Brain damage, such as cortical blindness, is an uncommon but known complication when the cerebral cortex experiences acute hypoxic damage. (nolan-law.com)
  • More than a decade ago, Lavie, a professor of Psychology and Neuroscience at UCL, originated load theory , explaining why inattention blindness only occurs during more demanding high-load tasks. (medicalxpress.com)
  • These effects of load on neural response explain inattentional blindness. (medicalxpress.com)
  • Fundoscopy should be normal in cases of cortical blindness. (wikipedia.org)
  • But it also leads to inattentional blindness, where we can't perceive unattended stimuli that are not part of the task even in cases when it's quite important to perceive them for example, an animal on the road while we're driving. (medicalxpress.com)
  • Vincristine-induced neurotoxicity is also well documented, but only a few cases of cortical blindness have been reported (4, 5) . (ajnr.org)
  • Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain's occipital cortex. (wikipedia.org)
  • MR findings of cortical blindness following cerebral angiography: is this entity related to posterior reversible leukoencephalopathy? (umassmed.edu)
  • Blindness is when someone has little, or no sight, and needs to rely on their other senses like touch and hearing to understand and get around. (va.org.au)
  • Cortical blindness and agnosia are usually stroke related, which can also link to dementia. (agingcare.com)
  • Patients with cortical blindness will not be able to identify the item being questioned about at all or will not be able to provide any details other than color or perhaps general shape. (wikipedia.org)
  • In patients with acquired cortical blindness, a permanent complete loss of vision is rare. (wikipedia.org)
  • In this article, we report three patients treated with immunosuppressive drugs and chemotherapy (vincristine, methotrexate) in whom cortical laminar necrosis developed. (ajnr.org)
  • Also known as face blindness, prosopagnosia is associated with damage to specific parts of the temporal lobes. (scienceblogs.com)
  • There is a difference between blindness and low vision even though these terms are often used interchangeably. (va.org.au)
  • This graph shows the total number of publications written about "Blindness, Cortical" by people in this website by year, and whether "Blindness, Cortical" was a major or minor topic of these publications. (umassmed.edu)
  • This fact underscores the metamodal theory of sensory cortical function and can be used to devise effective strategies to train the blind to compensate their loss through better use of the remaining sensory modalities. (bvsalud.org)