Low vision is a term for conditions which result in reduced sight and cannot entirely be corrected with eyeglasses, contact lenses, medicines or surgery. Several eye diseases or conditions can cause low vision. Let’s learn more about the four most common causes of low vision and their risk factors.
Macular degeneration is a disorder that affects the retina. This is the light sensitive tissue lining the inside of the eye. Within the retina, the area responsible for sharp central vision (called the macula) deteriorates, causing blurred vision. This can cause a blind spot in the central area of vision, which leads to low vision.
There are two types of macular degeneration – non-exudative (or dry form) and exudative (or wet form). The dry form usually progresses slowly, while the wet form causes more rapid and severe vision loss. Abnormal blood vessels develop under the macula and leak fluid and blood. The biggest risk factor for macular degeneration is age. Other risk factors include genetics, race, smoking, and high blood pressure.
Diabetic retinopathy is a diabetes complication that affects the eyes. High blood sugar levels cause damage to blood vessels in the retina. These blood vessels can swell and leak (called macular edema). Sometimes they close, stopping blood from passing through (called macular ischemia). At first, diabetic retinopathy may cause no symptoms or only mild vision problems. However, over time, it can severely damage the retina, leading to low vision. Anyone who has diabetes can develop diabetic retinopathy. The risk increases for those who have had diabetes longer, as well as those with poor control of blood sugar levels, high blood pressure or cholesterol. Smoking can also increase the risk.
A cataract is a clouding of the lens in the eye that affects vision. This clouding can block the light from reaching the retina at the back of the eye, resulting in general loss of vision. In some cases, a cataract can be surgically removed. Cataract surgery has a high success rate in otherwise healthy eyes. However, cataract surgery is not always possible for people who also have other eye diseases. The risk of cataract increases as you get older. Other risk factors include diabetes, smoking, alcohol use and prolonged exposure to ultraviolet sunlight.
Glaucoma is a disease that damages your eye’s optic nerve. Most commonly, this occurs when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve. There are four types: open angle, normal tension, angle closure, and secondary.