Patterns of vision and vision loss
- Central vision. The detailed vision we use when we look directly at something. Macular degeneration (AMD) affects central vision. Diabetic retinopathy can affect central or peripheral vision.
- Peripheral vision. The less detailed vision we use to see everything around the edges. Glaucoma affects peripheral vision first. Strokes can affect one side of the peripheral vision.
Contrast sensitivity. The ability to distinguish between objects of similar tones like milk in a white cup or to distinguish facial features. All eye problems can decrease contrast sensitivity.
- Depth perception. The ability to judge the position of objects. New vision loss in one eye can affect depth perception.
- Visual processing. The lens in our eye focuses light rays onto our retina. The retina converts these light rays into signals that are sent through the optic nerve to our brain, where they are interpreted as the images we see. A problem with any of these processes affects our vision in various ways.
The experience of vision loss
It is always a shock to learn that your vision loss cannot be reversed. It is important to recognize the anger and frustration you may feel, to get help working through these feelings, and to apply the strategies of vision rehabilitation to stay active. Doing all of these things will help you avoid depression (which may appear as fatigue or lack of interest). If you are depressed, seek treatment and counseling. A good support group can help you recognize that your value to yourself and others does not depend on your vision and that you are worth the effort it takes to make the most of the vision you have.
 Hazy vision. |
What are the symptoms of low vision?
With low vision, you cannot see well enough to do everyday tasks — even with regular glasses, contact lenses, medicine or surgery.
There are many signs of vision loss: finding it difficult or impossible to read, write, shop, watch television, drive a car or recognize faces. It may be difficult to set dials or manage glare.
You might have trouble picking out and matching the color of your clothes. The lights may seem dimmer than they used to, making work or household chores more difficult.
The phantom visions of Charles Bonnet syndrome
About 20 to 30 percent of people with vision loss see lifelike images they know are not real. This is called Charles Bonnet syndrome (CBS). It is important to understand that this syndrome is not a loss of mental capacity, but just part of vision loss for some.
The most common types of low vision include loss of central vision, loss of peripheral (side) vision, night blindness, blurred vision and hazy vision.
Who is at risk for low vision?
Low vision can be caused by eye injuries or by diseases, such as:
- Macular degeneration;
- Glaucoma;
- Diabetic retinopathy;
- Retinitis pigmentosa.
These conditions can occur at any age but are more common in older people. However, normal aging of the eye does not lead to low vision.
Low vision may also result from cancer of the eye, albinism or a brain injury. If you have these disorders or are at risk for them, you are also at greater risk for low vision.
Regular medical eye exams by an ophthalmologist (Eye M.D.) are important to diagnose eye diseases, treat those conditions that can be helped, and start the process of vision rehabilitation for people with low vision.
How is low vision diagnosed?
Your Eye M.D. can tell the difference between normal changes in an aging eye and those caused by eye diseases. If you have noticed changes in your vision, see your eye doctor right away.
A complete eye exam involves a number of tests designed to evaluate your vision and check for eye diseases. Your doctor may use a variety of instruments, aim bright lights directly at your eyes, and ask you to look through an array of lenses.
The eye exam usually begins with questions about your medical history and any vision problems you might be experiencing.
Next, your doctor will check your eyes with a light to see whether the outside of your eyes are functioning correctly and whether there are any signs of injury or disease. Your eyes will also be tested for visual acuity — how well you see.
Last reviewed and updated in March 2010,
by the American Academy of Ophthalmology.
