• Tunnel vision (lack of vision in the periphery) and blind spots are examples of visual field loss.
• Legal blindness. In North America this is 20/200 or less central visual acuity in the better eye with best possible correction, or a visual field of 20 degrees or less.

Causes of Low Vision

Eye diseases are a common cause of low vision:

• Hazy, blurry vision can result from cataracts.
• Blurred or partially obscured central vision is typical of macular degeneration.
• Diabetic retinopathy causes blind spots, blurriness and visual distortions.
• Poor peripheral vision is a hallmark of glaucoma.
• Retinitis pigmentosa reduces peripheral vision and the ability to see in the dark.
• Light sensitivity and loss of contrast are other symptoms of these and other diseases.

Heredity and eye injuries also can result in low vision.

Impact of Low Vision

Children as well as adults can be visually impaired, sometimes because of a birth defect or an injury. Children with low vision may have problems in learning concepts, and they need special instruction from their earliest years on. They also need additional help with socialization among other children and adults.

But low vision more commonly affects adults and seniors. Their vision loss can be very traumatic, leading to frustration and depression.

Losing the ability to drive safely, read quickly, watch television or view a computer screen can cause people with low vision to feel shut off from the world. They may be unable to get around town independently or shop for food and other necessities.

Management of Low Vision

If you have a vision impairment that interferes with your ability to perform everyday activities and enjoy life, your first step is to see an eye care professional for a complete eye exam.

Poor vision that cannot be corrected with eyeglasses or contact lenses could be the first sign of a serious eye disease such as age-related macular degeneration, glaucoma or retinitis pigmentosa.

Or it could mean you are developing a cataract that needs removal. Whatever the case, it's wise to take action before further vision loss occurs.

If your eye doctor finds that you have vision loss that cannot be corrected adequately with standard eyewear, medical treatment or surgery, he or she will help you take the next steps toward coping with your new situation.

An ophthalmologist who doesn't work in the low vision area would refer you to a low vision specialist.

A low vision specialist can evaluate the degree and type of vision loss you have, prescribe appropriate low vision aids such as lighted handheld magnifiers, digital desktop magnifiers and bioptic telescopes, and help you learn how to use them.

Newer options include handheld digital magnifiers for shopping or eating out, as well as software that simplifies computer use with magnification and text-to-speech features.

The low vision specialist also can recommend non-optical adaptive devices, such as large-face printed material, audio recordings, special light fixtures and signature guides for signing checks and documents. Special eyewear with tinted UV filters can help with light sensitivity and heighten contrast.

If necessary, your specialist or eye doctor also can refer you to a mental health professional and/or mobility coach to help you cope with your vision loss.