Rare, inherited vision disorder in which a person has little or no ability to see color. People with achromatopsia also commonly experience some vision loss, especially in bright light, to which they are extremely sensitive. The severity of achromatopsia varies. Although there is no cure or treatment for this disorder, people with achromatopsia can manage its symptoms. For example, they can wear sunglasses or tinted contact lenses to cope with bright light. They can use magnifiers and other devices for low vision to help them read, and telescopes to help them see distant objects.
Age-related macular degeneration (ARMD)
See macular degeneration.
A hereditary condition characterized by a variable lack of pigment in the eyes, skin, or hair. People with albinism may have pale pink skin and blond to white hair, but there are different types of albinism, and the amount of pigment varies. The irises of their eyes may be white or pinkish. They are sensitive to bright light and glare and commonly have other vision problems. While some people with albinism can see well enough to drive, many have impaired vision or may even be legally blind. Tinted eyeglasses, bifocals, magnifiers, and other optical devices can help people with this condition. Albinism is often accompanied by nystagmus or strabismus. People with albinism are sensitive to bright light and glare and may wear tinted eyeglasses. Bifocals, magnifiers, and other optical devices can help people with albinism.
A condition in which a person’s vision does not develop properly in early childhood because the eye and the brain are not working together correctly. Amblyopia, which usually affects only one eye, is also known as “lazy eye.” A person with amblyopia experiences blurred vision in the affected eye. However, children often do not complain of blurred vision in the amblyopic eye because this seems normal to them. Early treatment is advisable, because if left untreated, this condition may lead to permanent vision problems or even partial blindness. Treatment options include vision therapy exercises, prescription eyeglasses, or surgery. People with amblyopia may need to wear an eye patch over their stronger eye in order to force the affected eye to function as it should.
Partial or complete absence of the iris of the eye. This rare condition, usually present at birth, results in impaired vision and sensitivity to light. People with aniridia are also at high risk for certain other eye conditions, such as glaucoma, nystagmus, and cataracts. People with aniridia may benefit from wearing tinted contact lenses or sunglasses, using magnifiers, and avoiding intense or glaring light.
Rare condition in which one or both eyes do not form during pregnancy. When both eyes are affected, blindness results. There is no cure for anopthalmia. Prosthetic eyes can promote proper growth of the eye sockets and development of facial bones and also serve cosmetic purposes.
Absence of the lens of the eye. Aphakia is usually associated with the surgical removal of a cataract but may also result from a wound or other cause. Without the lens, the eye cannot adjust its focus for seeing at different distances. Contact lenses or eyeglasses are used to correct the vision of someone with aphakia. In cataract surgery, an artificial lens is inserted to replace the lens removed. A person with aphakia will benefit from good, but not excessive, lighting and high-contrast reading materials.
Common vision condition, usually present from birth, caused by an irregularly curved cornea or lens. People with astigmatism may experience blurred vision, eyestrain, or headaches. Two-thirds of Americans who have myopia also have astigmatism. Astigmatism can be corrected with eyeglasses or contact lenses. Corrective surgery is another option.
Rare, inherited condition that affects the macula, the area in the middle of the retina, and can cause blurred or distorted vision or a loss of central vision. Best’s Disease, also known as Vitelliform Macular Dystrophy, may affect both eyes. The disease’s effects on sight vary and may not become severe for many years, if ever. Most people are not significantly affected until after age 40. There is no treatment for Best’s Disease, but a person whose vision is impaired by this disease may benefit from devices for low vision.
A condition in which the lens of the eye, which is normally clear, becomes cloudy or opaque. Cataracts generally form slowly and without pain. They can affect one or both eyes. Over time, a cataract may interfere with vision, causing images to appear blurred or fuzzy and colors to seem faded. Most cataracts are related to aging. In fact, cataracts affect more than 50 percent of all adults by age 80 and are the primary cause of vision loss in people 55 and older. People with early cataract may benefit from new eyeglasses, bright lighting, anti-glare sunglasses, or magnifying lenses. If, despite such devices, cataract interferes with daily activities, surgery is the only effective treatment. Cataract surgery, which is common, involves removal of the cloudy lens and replacement with an artificial lens.
Charles Bonnet syndrome
Visual disturbances usually occurring in people who have experienced visual impairment or sight loss later in life, as through macular degeneration. People with Charles Bonnet syndrome may see a wide range of images, from simple patterns to people, animals, and buildings. The visual disturbances associated with this syndrome are not signs of mental illness, and people realize that the images they are seeing are not real. There is no cure for Charles Bonnet syndrome. However, the symptoms often stop on their own. People who have Charles Bonnet syndrome should consult with an eye care spet because treatment for vision disorders may help.
Rare disorder that causes progressive loss of the choroid, an important layer under the retina that is responsible for some of its blood supply. Choroideremia is an inherited disorder that generally affects males only. It commonly begins as night blindness in childhood and gradually advances to increasing vision loss. Most people with this disorder are able to retain good vision until age 40 or 50. There is no treatment for choroideremia, but people who have the disorder may find it helpful to use optical, electronic, or computer-based devices for low vision.
A cleft or gap in some part of the eye, such as the iris, lens, or retina, that is caused by a defect in the development of the eyeball. How much coloboma affects a person’s vision depends on the size and location of the cleft and on whether it occurs in one or both eyes. For example, someone with only a tiny defect in the iris may have normal vision. However, a person with large defects in the retina and optic nerve may have limited vision. Children whose vision is impaired by coloboma may benefit from using reading materials that have large black print and well-spaced letters and words. They may also find it helpful to read one line at a time with the aid of a cutout reading window.
A vision problem in which a person has difficulty distinguishing certain colors—most commonly red and green, but sometimes blue and green or blue and yellow. Color blindness is not really a form of blindness, but rather a deficiency in color perception. It usually affects both eyes and is much more common in males than in females. There is no treatment or cure for this problem, but a color-blind person can learn to adapt in various ways. For example, a color-blind driver can remember that the light positioned at the top of a traffic light is the red one. It is beneficial to diagnose color blindness in children at an early age so that steps can be taken to avoid learning problems related to color perception.
Inherited disease that, over time, causes deterioration of the specialized light-sensitive cells of the retina. People with cone-rod dystrophy typically experience decreased sharpness of vision followed by a loss of peripheral vision and color perception. The most common form of cone-rod dystrophy is retinitis pigmentosa. There is no treatment or cure for this disease, which is also referred to as cone-rod degeneration, progressive cone-rod dystrophy, and retinal cone dystrophy.
Congenital eye defects
Any of various conditions present at birth that affect the eyes or vision. Some congenital eye conditions, such as retinitis pigmentosa, are passed on through genes. Others, such as vision loss due to German measles, result from a disease or deficiency during pregnancy. Sometimes, as in the case of coloboma, the cause of a congenital eye defect is not known. Congenital eye defects can impair vision or even cause blindness. Some conditions are immediately apparent in an infant, while others may not become known until later in life.
Disease or disorder that affects the cornea, the clear, curved surface that covers the front of the eye. The effects of corneal disease vary. Some corneal conditions cause few, if any, vision problems. For example, infections of the cornea can often be treated with antibiotics. However, if the cornea becomes cloudy, light cannot penetrate the eye to reach the retina, and severe visual impairment, or even blindness, may result. Corneal dystrophies are usually inherited conditions in which one or more parts of the cornea lose their clarity due to a buildup of cloudy material. Keratoconus is the most common corneal dystrophy in the United States. When corneal disease causes the cornea to become permanently clouded or scarred, doctors may be able to restore vision with a corneal transplant—surgical replacement of the old cornea with a new one.
Cortical visual impairment
Visual impairment caused by damage to the part of the brain related to vision. Although the eye is normal, the brain cannot properly process the information it receives. The degree of vision loss may be mild or severe and can vary greatly, even from day to day. Cortical visual impairment may be temporary or permanent. People with cortical visual impairment have difficulty using what their eye sees. For example, they may have trouble recognizing faces, interpreting drawings, perceiving depth, or distinguishing between background and foreground. Children with cortical visual impairment are often able to see better when told in advance what to look for. Cortical visual impairment is also known as neurological visual impairment (NVI).
Rare disorder, present at birth, in which the optic nerve is underdeveloped, the pituitary gland does not function properly, and often a portion of brain tissue is not formed. De Morsier’s Syndrome, also known as septo-optic dysplasia, may cause blindness in one or both eyes and is also often accompanied by nystagmus and various other symptoms. Some children with De Morsier’s Syndrome have normal intelligence, while others may be developmentally delayed, learning-disabled, or mentally retarded. Some symptoms of this disorder can be treated, but the visual impairment usually cannot be corrected. Visual devices, such as a magnifier or a computer designed for visually impaired users, may benefit some people with De Morsier’s Syndrome.
Eye condition that results from the damaging effect of diabetes on the circulatory system of the retina. The longer someone has had diabetes, the greater the person’s likelihood of developing diabetic retinopathy. Changes in the tiny blood vessels of the retina can lead to vision loss. People with diabetes should have routine eye examinations so that diabetes-related problems can be diagnosed and treated as soon as possible. Maintaining strict control of blood sugar levels helps to prevent diabetic retinopathy. Surgical and laser treatments can help many people affected with this condition.
Dry eye syndrome
Persistent dryness of the eyes resulting from too little production of tears or too rapid evaporation of tears. People with dry eye syndrome may experience such symptoms as itching, burning, or stinging eyes. Some people feel as though something is caught in their eye, causing an irritation. Dry eye syndrome has many causes. For example, it may be linked to wearing contact lenses for long periods of time or to living in a dry or dusty climate. It may be a side effect of medication or a symptom of certain diseases. An eye doctor may recommend the application of special eye drops—”artificial tears”—to moisten the eyes or the use of a humidifier to increase humidity in the air. Not rubbing the eyes and avoiding such irritants as tobacco smoke can also help persons with dry eye syndrome. There is also now medication to treat moderate to severe dry eye.
Floaters and spots
Specks or strands that seem to float across the field of vision. Floaters and spots are actually shadows on the retina cast by tiny bits of gel or cells inside the clear fluid that fills the eye. Floaters and spots usually are normal and harmless. However, in some cases they may warn of serious conditions such as retinal detachment, diabetic retinopathy, or infection. Someone who experiences a sudden decline in vision accompanied by flashes and floaters or a sudden increase in the number of floaters should consult an ophthalmologist urgently. Floaters and spots generally do not require treatment. In those rare instances when they significantly impair vision, surgery may be an option.
Disease in which the pressure of the fluid inside the eye is too high, resulting in a loss of peripheral vision. If the condition is not diagnosed and treated, the increased pressure can damage the optic nerve and eventually lead to total blindness. Vision lost as a result of such damage cannot be restored. A person who has glaucoma may not realize it at first, because the disease often progresses with no symptoms or warning signs. Early detection through regular eye examination and prompt treatment is essential to prevent vision loss. Daily medication (usually eye drops), surgery, or a combination of both enables most people to control their intraocular pressure and retain their vision.
Blindness affecting half of the field of vision. Hemianopia, also known as hemianopsia, may be caused by various medical conditions, but usually results from a stroke or brain injury. It may affect either the right or left side of the visual field and is usually permanent. Hemianopia can produce various effects, from minor to severe. For example, a person may be able to see only to one side when looking ahead, or objects that the person sees may differ in clarity or brightness. Such visual impairment can make it difficult to perform daily tasks, from reading to crossing streets. There is no specific treatment for hemianopia, but low vision rehabilitation spets can help people learn to make the most of the sight that they have. In addition, some people with hemianopia benefit from the use of magnifiers or special prism lenses.
This common vision problem, also known as farsightedness, occurs when light rays entering the eye focus behind the retina, not directly on it. People with hyperopia are usually able to see distant objects well, but close objects appear blurry. Hyperopia may cause eyestrain or headaches, especially with reading. Eyeglasses or contact lenses can correct hyperopia. For people who do not want to wear glasses or contact lenses, laser vision correction is sometimes possible.
Rare condition, often inherited, in which the cornea becomes progressively thinner and gradually bulges outward, causing blurred or distorted vision. Keratoconus usually affects both eyes. At first, people with this condition can correct their sight with eyeglasses. However, as symptoms worsen over time, specially designed contact lenses are needed to improve vision. Most people with keratoconus will not experience severe visual impairment. However, as many as one in five will eventually require a corneal transplant (surgical replacement of the old cornea with a new one).
Rare, inherited disorder affecting many parts of the body. People with this condition have retinitis pigmentosa accompanied by mental retardation, paralysis of the legs, and various other symptoms.
Leber’s congenital amaurosis
Inherited condition, probably caused by degeneration of the retina, in which an infant is born blind or develops severe vision loss soon after birth. Children with Leber’s congenital amaurosis typically also have nystagmus, and some also have mental retardation and hearing disorders. At present, there is no treatment for this condition.
A level of visual impairment that has been defined by law to determine eligibility for benefits. It refers to central visual acuity of 20/200 or less in the better eye with the best possible correction, as measured on a Snellen vision chart, or a visual field of 20 degrees or less.
Vision loss that may be severe enough to impede a person’s ability to carry on everyday activities, but still allows some functionally useful sight. Low vision may be caused by macular degeneration, cataracts, glaucoma, or other eye conditions or diseases. Low vision may range from moderate impairment to near-total blindness. It cannot be fully corrected by eyeglasses, contact lenses, or surgery. However, a person with low vision may benefit from any of a variety of available optical devices, such as electronic magnifying glasses or eyeglass-mounted telescopes. In addition, special software developed for computer users with low vision can display type in large size or read text aloud.
Disease that causes dysfunction of the macula, the area in the middle of the retina that makes possible the sharp central vision needed for such everyday activities as reading, driving, and recognizing faces and colors. The condition is commonly known as age-related macular degeneration (ARMD) and is the leading cause of visual impairment among older people. However, there are also other types of macular degeneration, such as Stargardt’s Disease and Best’s Disease. Macular degeneration causes blurred, distorted, or dim vision or a blind spot in the center of the visual field. Peripheral vision is generally not affected. This condition is painless and may progress so gradually that the affected person at first notices little change. There is no cure for macular degeneration, but drug therapy, laser surgery, or other medical treatment may in some cases be able to slow the disease’s progression or prevent further vision loss. People with macular degeneration can also benefit from the use of various devices for low vision, such as magnifiers, high-intensity lamps, and pocket-sized telescopes.
Disorder of the connective tissue, affecting the heart and blood vessels, skeletal system, eyes, and other parts of the body. The condition is present at birth. Symptoms vary from person to person, ranging from mild to severe. People with Marfan syndrome are often nearsighted (see myopia), and about half have dislocation of one or both lenses of the eye. There is no cure for Marfan syndrome. Treatment depends on which body systems are affected. Early eye examinations can detect vision problems related to the disorder, which can usually be corrected with eyeglasses or contact lenses.
Rare disorder, usually inherited, in which one or both eyes are abnormally small. The degree of visual impairment varies, from reduced vision to blindness. Extreme microphthalmia resembles some forms of anopthalmia. There is no treatment or cure for micropthalmia. In certain cases, artificial eyes can be used to promote proper growth of the eye sockets and to help with cosmetic appearance.
This condition, commonly known as nearsightedness, occurs when light rays entering the eye focus in front of the retina, not directly on it. People with myopia are usually able to see close objects well, but objects in the distance—such as highway signs or writing on a chalkboard—appear blurred. People with this condition may squint to see distant objects and experience eyestrain or, sometimes, headaches. Eyeglasses or contact lenses can correct myopia. Surgery is another alternative.
Neurological visual impairment (NVI)
See cortical visual impairment.
Condition that involves involuntary, rapid, repetitive movements of one or both eyes from side to side, up and down, or in a circular motion. Nystagmus may be present at birth or, less commonly, may result from disease or injury. In some cases, the condition can reduce or interfere with vision. For example, children with nystagmus may frequently lose their place when reading. Placing a cutout reading window over words or using a card to “underline” text can be helpful.
Optic nerve atrophy
Degeneration of the optic nerve, which carries vision information from the eye to the brain. People who have optic nerve atrophy may have dimmed or blurred vision as well as a reduced field of vision. They may also have difficulty seeing contrast and fine detail. Vision loss through optic nerve atrophy is permanent. However, if the underlying cause can be identified and successfully treated, further vision loss may be prevented. Bright lighting, high contrast, and bold colors can help children with optic nerve atrophy see more clearly.
Optic nerve hypoplasia
Condition, present at birth, in which the optic nerve is underdeveloped, so that adequate visual information is not carried from the eye to the brain. The effects of optic nerve hypoplasia have a broad range, from little or no visual impairment to near-total blindness. The condition may affect one or both eyes. There is no treatment or cure for optic nerve hypoplasia. However, depending on the degree of visual impairment, a person with this condition may benefit from the use of devices for low vision.
The eye’s gradually decreasing ability to focus on nearby objects. Presbyopia is a normal part of aging and affects virtually everyone, usually becoming noticeable after age 40. People with presbyopia typically hold reading materials at arm’s length in order to bring the words into focus. They may experience headaches or eyestrain while reading, viewing a computer screen, or doing close work. Presbyopia can be corrected with reading glasses, bifocal or variable focus lenses, or contact lenses. Using bright, direct light when reading is also helpful.
Separation of the retina from the underlying supportive tissues. Retinal detachment may result from injury, disease, or other causes. This condition occurs most often in middle-aged and elderly people. A person with retinal detachment usually does not experience pain, but may see floaters (see floaters and spots) or bright flashes of light, may have blurred vision, or may see a shadow or curtain over part of the field of vision. Retinal detachment requires prompt medical attention to prevent permanent vision loss. There are several methods of treatment for retinal detachment, including laser surgery.
Degeneration of the retina, resulting in decreased night vision, a gradual loss of peripheral vision, and in some cases, loss of central vision. The degeneration progresses over time and can lead to total blindness. Retinitis pigmentosa is a rare, inherited disease for which there is as yet no treatment or cure. Some opthalmologists believe that treatment with high s of Vitamin A can slow the progression of retinitis pigmentosa, and that taking Vitamin E makes it worse. Early diagnosis enables a person with the disease to plan and prepare for its progression. In addition, depending on the degree of vision loss, electronic magnifiers, night-vision scopes, and other such special devices for impaired vision can provide some benefit for people with the disease.
Malignant tumor (cancer) of the retina, generally affecting children under the age of 6. Usually hereditary, retinoblastoma may affect one or both eyes. Retinoblastoma has a cure rate of over 90 percent if treated early. Without prompt reatment, the cancer can spread to the eye socket, the brain, and elsewhere, and can cause death. Depending on the size and location of the tumor, treatment options include laser surgery, cryotherapy (a freezing treatment), radiation, and chemotherapy. In some cases, the affected eye may need to be removed.
Retinopathy of prematurity (ROP)
Condition associated with premature birth, in which the growth of normal blood vessels in the retina stops, and abnormal blood vessels develop. As a result, the infant has an increased risk of detachment of the retina (see retinal detachment). Retinopathy of prematurity can lead to reduced vision or blindness. Laser therapy can help this condition if diagnosis and treatment occur early. Children who experience minor effects may benefit from the use of devices for low vision as they get older. Retinopathy of prematurity was formerly called retrolental fibroplasia.
See retinopathy of prematurity.
See Cone-rod dystrophy.
Gap or blind spot in the field of vision that may result from damage to the retina. How much a scotoma impairs sight depends mainly on whether it affects central or peripheral vision. Common causes of scotoma include macular degeneration, glaucoma, and inflammation of the optic nerve. People who experience significant vision loss because of scotomas may benefit from the use of magnifiers, bright lighting, and large-print reading materials.
Septo-Optic Dysplasia (SOD)
See DeMorsier’s Syndrome.
Inherited disease that causes gradual degeneration of the macula, the area in the middle of the retina that makes possible the central vision needed for reading, driving, recognizing colors, and other activities of daily life. Effects of Stargardt’s Disease, which start at an early age, vary from minor to total loss of detail vision. Over a period of years, people with the disease typically lose sharpness of vision, experience decreased color vision, and may have blind spots. However, peripheral and night vision usually remain unaffected, and complete loss of sight is rare. There is no cure or treatment for Stargardt’s Disease, but such devices as magnifying screens and binocular lenses can help people cope with vision limitations.
Condition in which the eyes are not both directed toward the same point simultaneously. Strabismus occurs when eye muscles are not working together properly. It is most commonly an inherited condition, but may also be caused by disease or injury. If diagnosed early, strabismus can usually be corrected. The condition may be treated with corrective eyeglasses, eye-muscle exercises, surgery, or a combination of these approaches. Young children with this condition may need to wear an eye patch over their stronger eye to force their weaker eye to function correctly. Children whose strabismus is not corrected may develop amblyopia.
Disorder, present at birth, characterized by a facial birthmark and any of various neurological, visual, and developmental symptoms. People with Sturge-Weber syndrome may, for example, experience seizures, glaucoma, partial paralysis, and learning disabilities. There is no cure for Sturge-Weber syndrome, but many of the symptoms can be treated. For instance, medications may be prescribed to control seizures, and surgery or eye drops may be used to treat glaucoma.
Contagious eye infection, caused by bacteria, that affects the eyelid and cornea. Trachoma can lead to scarring and blindness if not treated. The infection is spread by contact with discharge from the eyes or nose of infected persons and also transmitted by certain flies. Trachoma is rare in the United States, but it affects millions of people around the world, many of them children. Antibiotics are generally an effective treatment for trachoma, especially if used early in the infection. In certain cases, eyelid surgery may be needed.
Inherited condition that causes partial or total hearing loss accompanied by gradual vision loss resulting from retinitis pigmentosa. Some people with Usher Syndrome also have problems with balance. There is no cure for the condition. However, early diagnosis makes it possible to help people with Usher Syndrome by providing hearing aids, training in sign language and lip reading, devices for impaired vision, and counseling for preparing for the future.
Inflammation inside the eye, affecting the structures that provide most of the blood supply to the retina. Uveitis may affect one or both eyes. The condition may be associated with an underlying disease or have other causes, but in many cases it affects people who are otherwise healthy. People with uveitis typically experience redness of the eye, blurred vision, and light sensitivity. They may also feel pain and see floaters (see floaters and spots). If not properly treated, uveitis can lead to scarring and vision loss. Treatment depends on which eye structures are affected and whether there is an underlying disease. Eye drops and other medications are commonly prescribed to reduce inflammation.
Vitelliform Macular Dystrophy
See Best’s Disease.
Courtesy Of Medlineplus.com