Ask a Teacher

A blind spot is a distortion or absence of sight in a small portion of the visual field. Blind spots that completely eradicate vision are called negative scotomas, while spots that look like steady or flashing lights are called positive scotomas. These spots often go unnoticed unless they interfere significantly with vision.

A wide range of medical problems can lead to the development of blind spots.

Among the most common causes are glaucoma, in which abnormally high fluid pressure builds up inside the eye, and diabetic retinopathy, in which blood vessels in the retina overgrow and burst after a long history of diabetes. Macular degeneration, a deterioration of part of the retina, causes blind spots in the central part of the field of vision; distortion of straight lines is an early sign of the disorder. Atherosclerosis (the buildup of fatty deposits inside arteries) in the artery that feeds the retina can cause a blind spot as well. Strokes, also caused by atherosclerosis, sometimes manifest themselves as blind spots, but other stroke symptoms almost always accompany the visual disturbance. Migraine headaches cause temporary blind spots. Alcohol abuse, multiple sclerosis, and pituitary tumors may also result in blind spots.