r even left alone. Because of the seriousness of a retinal detachment, however, anyone who notices new flashes and floaters needs to have an exam of the retina promptly. Fixing a retinal detachment requires complicated surgery; it is much better to treat it sooner rather than later.
The part of the retina responsible for central vision and fine visual acuity is the macula. Aging changes in the macula, called age-related macular degeneration, are one of the most common eye problems and the one that people seem to dread the most. Macular degeneration is caused by the breakdown of an insulating, outer layer of the retina. In the common, “dry” stage, the light-converting cells in the macula slowly deteriorate. In the less common but more serious “wet” form, harmful elements in the blood are able to reach the retina, damaging and scarring it.
Macular degeneration never causes total blindness, because it does not affect peripheral vision, but it makes images in the central vision appear extremely warped or blurry, and activities like driving a car or reading become difficult or impossible.
Good nutrition, exercise, adequate zinc intake, and not smoking are thought to prevent or slow the progression of macular degeneration, and many people with early macular degeneration continue to see well enough to lead a normal life. There are also some laser treatments, as well as a type of injectable medicine ranibizumab (brand name Lucentis), for the most severe kind of macular degeneration.
If vision loss reaches the level at which a person can no longer read with ordinary glasses, optical magnification systems and closed-circuit TV systems (although they are bulky and rather expensive) provide even greater magnification. When print is magnified, you only see a small area of what you are reading at any one time. This can take a little getting used to, but it is far better than being unable to read.
The main reason people with diabetes are encouraged to have regular eye exams is to look for changes in the blood vessels of the retina that indicate diabetic retinopathy. Diabetic retinopathy develops as prolonged exposure to high blood glucose weakens the walls of the blood vessels in the eyes. The longer a person has had diabetes and the greater his exposure to high blood glucose, the greater his risk of having this condition.
The earliest signs of diabetic retinopathy are little red or white spots on the retina that can only be seen by an eye doctor. These spots are microaneurysms, tiny pouches of blood that have bulged through the damaged blood vessel walls and can leak blood, fat, and fluid into the retinal tissues. These early changes in the blood vessels are called background, or nonproliferative, retinopathy. Leaking in the retina from background retinopathy can cause some blurring of vision, but it does not usually require immediate treatment.
If diabetic retinopathy causes damage near the macula, however, fluid leaking into the macula makes it swell like a mosquito bite. This swelling, called macular edema, is the most common cause of visual impairment in diabetic retinopathy. (Reduced blood supply to the macula is a less common occurrence. As yet, it is not treatable.)
The earliest changes of retinopathy can even be temporary: here today and gone in six months. If damage continues, though, the risk increases that new, abnormal blood vessels will start to sprout in retina and poke through into the vitreous. This important change is called going from background retinopathy to proliferative retinopathy.
The new blood vessels apparently proliferate in an attempt to increase blood and oxygen supply to the damaged retina. They are so fragile, though, that they rupture at a cough, a sneeze, or even during sleep. Blood pours into the retina, blocking vision suddenly. When the bleeding stops, scar tissue forms, tugging at the retina and adding the potential for a retinal detachment.
Untreated proliferative retinopathy usually leads to blindness. Not long ago, diabetic retinopathy was just about the most discouraging condition that ophthalm