Blindness

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Neurofibromatosis I, enlarged optic foramen

Overview Treatment

Blindness

Blindness is the lack of vision, or aloss of vision that cannot be corrected with glasses or contact lenses. Blindnessmay be partial, with very limited vision, or complete,with no perception of light. People with vision worse than 20/200, or a field of vision of less than 20 degrees in the better eye, are considered legally blind in most states in the U.S.

Blindness has many causes. In the United States, the leading causes are diabetes, glaucoma, macular degeneration, and accidents (such as chemical burns or injuries from bungie cords, fishing hooks, fireworks, racket balls, and similar objects).

Worldwide, the leading causes of blindness are cataracts, onchocerciasis (river blindness), trachoma, leprosy, and vitamin A deficiency.

Other causes include:

• Blocked blood vessels
• Complications of premature birth (retrolental fibroplasia )
• Complications of eye surgery
• Lazy eye
• Optic neuritis
• Stroke
• Tay-Sachs disease
• Retinitis pigmentosa
• Retinoblastoma
• Lead poisoning
• Optic glioma

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