People with loss of vision may see nothing whatsoever, or they may be able to distinguish light from dark and may even be able to detect vague shapes Loss of vision is a complete or nearly complete absence of sight.. Loss of vision may involve part or all of the visual field of one or both eyes and may be sudden or gradual, temporary or permanent. People usually notice sudden loss of vision immediately. However, gradual loss may not be noticed and may not be discovered for some time perhaps not until a car accident or other event prompts a thorough vision examination.
Common causes include blockage of the blood supply to the retina, diabetes, disorders that damage the optic nerve, glaucoma, cataracts, macular degeneration, injuries, and, in certain areas of the world, infectionsComplete loss of vision may occur in one or both eyes.. Occasionally, complete or partial loss of vision occurs temporarily. This temporary loss of vision can be caused by a transient ischemic attack (sometimes called a mini stroke).
Many types of loss of vision involve only part of the visual field (visual field defects). A stroke or tumor for example, that affects the left side of the brain could result in an inability to see all or part of the right side of the visual field in both eyes (affected people can still see normally on the other side in both eyes). Another type of visual field defect results in an inability to see the outside part of the visual field in either eye. This pattern of visual field loss can be caused by a problem such as a tumor or aneurysm near the pituitary gland (which lies just below the brain, behind a cross-over of the optic nerve fibers). In the center of their visual field some people lose the ability to see things, but they retain their side or peripheral vision (where things are seen out of the “corner of the eye”). This type of defect can be caused by macular degeneration and certain disorders that damage the optic nerve. We see smaller, irregular patches of vision may be lost as a result of disorders that damage the retina, such as diabetic retinopathy, hypertensive retinopathy, and retinal detachment. Loss of peripheral vision in all directions, so that the only remaining vision is in the middle of the field (tunnel vision), can be caused by glaucoma and certain retinal disorders .
