Inability to see with one or both eyes. Transient blindness (blackout) can result from vertical acceleration causing high gravitational forces, glomerulonephritis (a kidney disease), or a clot in a blood vessel of the eye. Continuing blindness may arise from injuries or diseases of the eye (e.g., cataract, glaucoma), including the retina, the optic nerve, or the brain's visual centres. Many infectious, noninfectious, and parasitic systemic diseases can cause blindness. Sexually transmitted diseases and rubella in pregnant women can cause blindness in their infants. See also macular degeneration; visual-field defect.

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