Macular degeneration is a progressive eye disease characterized by damage to the macula, the central part of the retina. There are two types of macular degeneration. Dry macular degeneration causes damage to light-sensitive cells, while wet macular degeneration causes leaking blood vessels that scar the eye, according to the Merck Manual of Health and Aging. Both wet and dry macular degeneration cause a loss of central vision, although additional signs and symptoms may vary slightly by type.
Loss of Central Vision
A hallmark symptom of macular degeneration is the loss of central vision. While those with dry macular degeneration tend to experience slow, painless vision loss, individuals with the wet type of the disorder more often experience a sudden deterioration over a period of only days or weeks, according to the Merck Manual of Health and Aging. As macular degeneration progresses, the retina thins, which leads to a centralized blind spot in one or both eyes. This type of vision loss can make it difficult to see faces straight on, or to read, drive or watch television. To compensate, affected individuals may turn their heads and use their peripheral vision--which is usually spared in this condition--to help them see things.
Other Visual Distortions
Wet macular degeneration can cause visual distortions such as straight lines appearing wavy or crooked or doorways or signs appearing lopsided, according to the Mayo Clinic. It may also affect depth perception, causing objects to appear smaller or farther away than they actually are. Those with dry macular degeneration may have a particularly hard time seeing in dimly lit environments such as restaurants or theaters. The brightness and intensity of colors may also diminish, and everything in their view may be very hazy. According to the Merck Manual of Health and Aging, it is rare for macular degeneration to cause total blindness; however, if both eyes are affected, blindness can occur.
Charles Bonnet Syndrome
Charles Bonnet syndrome is a condition characterized by visual hallucinations that can commonly occur in individuals with later-stage macular degeneration. Those with advanced wet or dry macular degeneration may develop the syndrome.
A study published in the May-June 2008 issue of "Ophthalmic Epidemiology" found that poor visual acuity significantly increased the odds of visual hallucinations among macular degeneration patients. The most common visual images reported were of people, followed by geometric patterns. Most images were in color and appeared straight ahead in their central line of vision. They also tended to have moving parts and occur an average of once per day.
According to the Mayo Clinic, these images are the result of impaired communication between the macula and retina and the brain. Unlike some other types of hallucinations, visual hallucinations associated with Charles Bonnet syndrome are not a sign of mental illness.
References
- Merck Manual of Health and Aging: Macular Degeneration
- Mayo Clinic: Wet Macular Degeneration
- "Ophthalmic Epidemiology;" Charles Bonnet syndrome in age-related macular degeneration: the nature and frequency of images in subjects with end-stage disease; Khan JC et al.; May-June 2008
