How Do You Treat Low Vision?

Low vision means diminished vision; the visual acuity is 20/70 or worse that cannot be fully corrected by surgery, wearing glasses, or contact lenses. In the low vision, a person does not become completely blind; there is still some sight that can sometimes be coped with or improved with the help of visual aids and visual rehabilitation. With appropriate management and regular follow-up, vision loss can be prevented from worsening.

The American Optometric Association classifies low vision into two categories:

• Partially sighted: The person has visual acuity between 20/70 and 20/200 with conventional prescription lenses.
• Legally blind: The person has visual acuity no better than 20/200 with conventional correction and/or a restricted field of vision, which is less than 20 degrees.

The ratio measurement of vision:

This describes the visual acuity or the sharpness of vision at 20 feet from an object. For example, 20/70 vision means that the patient is at 20 feet to see what a person with normal vision would be able to see at 70 feet.

The most common types of low vision include:

• Loss of central vision: Characterized by a blind spot in the center of one's vision.
• Loss of peripheral (side) vision: The person does not have any vision on either side or above and below eye level. Central vision, however, remains intact.
• Night blindness: The inability to see in poor lighting or dark and when outside at night.
• Blurred vision: Objects both near and far appear blurry or out of focus.
• Hazy vision: The entire field of vision appears to be covered with a film of haze or glare.

Anyone at any age can be affected by low vision. Low vision is relatively more common in adults over the age of 45 and the risk increases further over the age of 75. Low vision is not a typical sign of aging. There may be one or more conditions causing low vision. These are usually the result of disorders or injuries affecting the eye or a systemic disorders affecting the eyes, such as diabetes. There are several causes of low vision, including:

• Diabetes/Diabetic retinopathy
• Macular degeneration
• Glaucoma (increased pressure in the eye)
• Cataracts
• Retinitis pigmentosa
• Inherited diseases
• Eye trauma
• Corneal opacity

Low vision can cause difficulty in performing daily activities. It can also be dangerous because it causes difficulty while driving, crossing the road, and operating heavy machinery. Hence, leading to accidents. People with low vision may experience the following symptoms:

• Loss of central vision
• Night blindness
• Loss of peripheral vision
• Blurred vision
• Hazy vision
• Difficulty distinguishing colors
• Difficulty identifying faces of people
• Difficulty viewing digital screens
• Eyestrain

A thorough eye examination is needed to diagnose the causes of low vision. Several diseases can cause low vision. Low vision can be diagnosed by an ophthalmologist by simple out-patient diagnostic tests as a part of a detailed eye exam. The doctor would ask the patient to read letters and numbers from different distances, near and far. The field of vision is also studied.