According to the American Foundation for the Blind, 22.5 million American Adults age 18 and older reported experiencing vision loss, and more than about 80 percent of them could have been avoided or cured.
That’s why regular eye exams are so important, they can be particularly helpful in detecting progressive eye conditions such as vision loss.
Loss of vision can occur suddenly or develop gradually over time. Vision loss may involve both eyes, only one eye or even certain parts of the eye. Vision loss can also be considered as loss of sight that cannot be corrected to a normal level with corrective lenses. The causes of loss of vision are extremely varied and range from conditions affecting the eyes to conditions affecting the visual processing centers in the brain. Impaired vision becomes more common with age. Common causes of vision loss in the elderly include diabetic retinopathy, glaucoma, age-related macular degeneration and cataracts.
Sudden loss of vision has three general causes. If you think you have one of these symptoms, we suggest you have a doctor monitor:
Clouding of normally transparent eye structures
Abnormalities of the retina
Abnormalities of the nerves that carry visual signals from the eye to the brain
Light must travel through several transparent structures before it can be sensed by the retina. First, light passes through the cornea (the clear layer in front of the iris and pupil), then the lens, and then the vitreous humor (the jellylike substance that fills the eyeball). Anything that blocks light from passing through these structures can cause loss of vision.
The most common causes of sudden loss of vision are:
Blockage of a major artery of the retina
Blockage of an artery to the optic nerve
Blockage of a major vein in the retina
Blood in the jellylike vitreous humor near the back of the eye
Sudden retinal artery blockage can result from a blood clot or small piece of atherosclerotic material that breaks off and travels into the artery. The artery to the optic nerve can be blocked in the same ways and can also be blocked by inflammation. A blood clot can form in the retinal vein and block it, particularly in older people with high blood pressure or diabetes. People with diabetes are also at risk of bleeding into the vitreous humor.
Sometimes what seems like a sudden start of symptoms may instead be sudden recognition. For example, a person with long-standing reduced vision in one eye (possibly caused by a dense cataract) may suddenly become aware of the reduced vision in the affected eye after covering the unaffected eye.
Even if a symptom appears and goes away, you are better off checking with your eye specialist if you encounter any of these warning signs. Eye symptoms should never be ignored.