Age-related macular degeneration (AMD) is the leading cause of blindness in the United States in individuals over 55 years old. In a normal eye, light enters the eye through the pupil and is then focused by the lens onto the retina, which lines the back of the eye. Here, color and images are defined, telling our brain what we are seeing. The macula (known as the macula lutea or yellow spot) is a small area that sits directly in the center of the retina and is responsible for defining details of an image and sorting out color. The underlying cause of macular degeneration is not yet well understood, although it appears a number of factors contribute to it.
As the macular area deteriorates, central vision worsens. AMD presents in two main forms: "wet" and "dry." Dry AMD, the most common form of the disease, results in a gradual thinning and atrophy of the retina. Wet AMD develops as a result of leakage from abnormal new blood vessels that occur underneath the retina in the macular area. This leakage ultimately leads to scarring of the macular retina with loss of central vision, although peripheral vision usually is preserved.
Laser photocoagulation* is a surgical procedure that may be used to treat the abnormal blood vessels in some forms of "wet" AMD. Recent evidence suggests that the progression of early AMD in some individuals who are at high risk for vision loss may be slowed with antioxidant dietary supplements.
Although fitness and diving issues for this disease are not well studied, there are no obvious restrictions for individuals diving with AMD, as long as his or her visual acuity is adequate to dive safely. There is no known increased risk of barotrauma or DCS from macular degeneration. (The described risk of abnormal retinal blood vessels leaking with pressure is a complex issue that is beyond the scope of this article.)
When diving, you should first have the approval of your physician for physical activity. If the diver has had laser photocoagulation therapy for AMD, he or she should wait two weeks and be cleared by an ophthalmologist before returning to diving. Motivated divers will find a way to get some diving in, but not at the risk of their eyesight. As we get older, an eye exam should be part of a regular physical examination to prevent or detect disease.
*A direction of an intense light beam to an area of the eye that produces localized coagulation by the absorption of light energy and its resultant conversion to heat. It is also used for treating retinal detachment and other ocular conditions.