Diseases Causing Blindness
Blindness Has No Boundaries
Over 285 million people in the world are visually impaired, with 39 million blind and 246 million with moderate to severe visual impairment.1 In the US alone, 1.3 million people are reported to be legally blind, with about 10% that are totally blind with no light perception.1,2
Causes of Vision Impairment and Blindness
The main causes of blindness are cataract (47.8%) and glaucoma (12.3%), with cataract being the leading cause of blindness in the world. Nearly 67 million people worldwide have glaucoma.1 See the table below for the other diseases that cause blindness, from low to high incidence.
Blindness Incidence and Risk Rates3
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Leber Congenital Amaurosis: Eye disorder that primarily affects the retina, typically presenting with severe visual impairment beginning in infancy. Other features include photophobia, nystagmus (involuntary movements of the eyes) and extreme farsightedness.
Genetic Retinoblastoma: A rare type of eye cancer that usually develops in early childhood, typically before the age of 5. This form of cancer develops in the retina, which is the specialized light‐sensitive tissue at the back of the eye that detects light and color. Signs and symptoms of retinoblastoma strabismus include; persistent eye pain, redness, irritation, and blindness or poor vision in the affected eye(s). 40% of retinoblastomas are germinal.
Cortical Blindness: Visual loss due to bilateral dysfunction of the occipital visual (striate) cortex (V1). It is often used to indicate severe visual impairment due to any type of bilateral dysfunction of the geniculocalcarine visual pathways. The onset of bilateral dysfunction of the geniculocalcarine visual pathways or the occipital cortex may be simultaneous or sequential.
Congenital Glaucoma: Characterized by elevated intraocular pressure, enlargement of the globe, edema, and opacification of the cornea with rupture of Descemet's membrane, thinning of the anterior sclera and iris atrophy, anomalously deep anterior chamber, and structurally normal posterior segment except for progressive glaucomatous optic atrophy. Depending on when treatment is instituted, visual acuity may be reduced and/or visual fields may be restricted. In untreated cases, blindness invariably occurs.
Optic Nerve Hypoplasia (ONH): A congenital anomaly of the optic disc that might result in moderate to severe vision loss in children. The major aspects of ophthalmic evaluation of an infant with possible ONH are visual assessment, fundus examination, and visual electrophysiology. Characteristically, the disc is small, there is a peripapillary double-ring sign, vascular tortuosity, and thinning of the nerve fiber layer.
Retinopathy of Prematurity: Abnormal blood vessel development in the retina of a premature infant. The blood vessels of the retina begin to develop about 3 months into pregnancy. They complete development at the time of normal birth. The eyes may not develop properly if a baby is born very early. The vessels may stop growing or grow abnormally from the retina into the back of the eye. The vessels are fragile. They can leak and cause bleeding in the eye. Scar tissue may develop and pull the retina loose from the inner surface of the eye. In severe cases, this can result in vision loss.
Cerebral Palsy: A group of disorders that can involve brain and nervous system functions, such as movement, learning, hearing, seeing, and thinking. In some people with cerebral palsy, parts of the brain are injured due to low levels of oxygen (hypoxia) in the area. It is not known why this occurs.
There are several different types of cerebral palsy. Some people have a mixture of symptoms. One nervous system symptom is vision problems.
Neuromyelitis Optica (NMO): An uncommon disease syndrome of the central nervous system that affects the optic nerves and spinal cord. Individuals with NMO develop optic neuritis, which causes pain in the eye, vision loss, and transverse myelitis.
Drug Overdose: An overdose is when you take more than the normal or recommended amount of something, usually a drug. An overdose may result in serious, harmful symptoms or death.
Hypoxia: A condition which occurs when there is not enough oxygen getting to the brain, which needs a constant supply of oxygen and nutrients to function. In some case this can cause vision problems. See cerebral palsy for more information.
Retinitis Pigmentosa: An eye disease in which there is damage to the retina. The cells controlling night vision (rods) are most likely to be affected. However, in some cases, retinal cone cells are damaged the most. The main sign of the disease is the presence of dark deposits in the retina. Retinitis Pigmentosa usually presents as "night blindness" and can progress to loss of central vision in advanced cases.
Vitamin Deficiency in Alcoholics: Chronic alcoholic patients are frequently deficient in one or more vitamins. Research shows that taking vitamin B12 with other vitamins including folic acid and vitamin B6 might help prevent the eye disease called age-related macular degeneration, one of the main causes of blindness.
Pernicious Anemia: A condition in which the body can't make enough healthy red blood cells because it doesn't have enough vitamin B12. Severe or long-lasting pernicious anemia can damage the heart, brain, and other organs in the body. It can also cause other problems, such as nerve damage and neurological problems.
Pituitary Tumors: An abnormal growth in the pituitary gland, the part of the brain that regulates the body’s balance of hormones. Symptoms caused by pressure from a larger pituitary tumor may include visual changes such as double vision, drooping eyelids, and visual field loss.
Diabetic Retinopathy: Diabetes can harm the eyes, damaging the small blood vessels in the retina and the back part of the eye. Most often, diabetic retinopathy has no symptoms until the damage to your eyes is severe. Symptoms of diabetic retinopathy include blurred vision and slow vision loss over time, shadows or missing areas of vision, and trouble seeing at night. People with type 1 or 2 diabetes are at risk of this condition.
Glaucoma: A group of eye conditions that lead to damage of the optic nerve, the nerve that carries visual information from the eye to the brain. In most cases, damage to the optic nerve is due to increased pressure in the eye.
Central Retinal Artery Occlusion: A blockage in one of the small arteries that carry blood to the retina. These blockages are more likely if there is hardening of the arteries in the eye. If a branch of the retinal artery is blocked, part of the retina will not receive enough blood and oxygen, possibly resulting in loss of vision.
Ischemic Optic Neuropathy: One of the major causes of blindness or seriously impaired vision. Ischemic optic neuropathy is primarily of two types: anterior (AION) and posterior (PION), involving the optic nerve head (ONH) and the rest of the optic nerve respectively. The development of various types of ischemic optic neuropathy are influenced by the optic nerve circulation, and also the various systemic and local risk factors.
Cataract: A clouding of the eye lens that often leads to decreased vision. It can be surgically treated if burdensome. Cataracts mostly occur with age. However, there are some that are congenital or can arise after injury, surgery to the eye, with diabetes, with steroid use, or with radiation.
Blindness Incidence and Risk Rates3
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Tap each disease for more information.
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References: 1. Lighthouse International Web site. Prevalence of Vision Impairment. http://www.lighthouse.org/research/statistics-on-vision-impairment/prevalence-of-vision-impairment/. Accessed November 5, 2013. 2. Czeisler CA, Shanahan TL, Klerman EB, et al. Suppression of melatonin secretion in some blind patients by exposure to bright light. N Engl J Med. 1995;332(1):6-11. 3. Data on File; Vanda Pharmaceuticals.
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