Infections caused by herpes or improper use of contact lenses can damage the cornea and lead to scarring. This prevents light from traveling through the eye. Contact sports injuries may cause issues such as a detached retina, which results in the eye being unable to sense light rays correctly. Swelling or blood clots can cut off the blood supply to the retina and cause similar issues. However, the most common cause of sudden loss of vision or blindness is ischemia.

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