How does the eye work?
The eye works in much the same way as a camera (figure 1). The cornea, pupil lens and vitreous gel are clear and allow light to focus on a thin sheet of tissue in the back called the retina. The retina itself has photoreceptor cells to transform light energy into nerve impulses as well as nerve fibers to transmit those impulses back to the optic nerve.

What is the macula?
The macula is a small area in the center of the retina and it contains a very high concentration of photoreceptor cells. It allows us to use our central vision to see small details.

What is macular degeneration?
Macular degeneration is a specific disease affecting about 15% of us as we age. The pigmented cells behind the retinal photoreceptor cells change in ways that may eventually affect vision. The changes are typically referred to as "dry" if there are no bleeding or leaking blood vessels involved. A recent study has shown that taking vitamin C (500mg), E (400 IU), beta carotene (15mg) and zinc (80mg) can reduce the risk of vision loss in patients with this condition.

What is "wet" macular degeneration?
In some eyes with macular degeneration abnormal vessels form and grow under the macula. These vessels are very leaky and cause blurred, distorted vision. These eyes generally benefit from laser treatment. Currently we are using a dye called visudyne to enhance the effectiveness of laser for this condition.

What is diabetic retinopathy?
Diabetic retinopathy is a primarily a disease of the retinal veins and capillaries. Patients with a history of diabetes for five or more years are at risk for retinopathy. Retinopathy can be diagnosed on a routine eye examination using the dilating drops to give your doctor a good view of the retina. The doctor looks for evidence of retinal swelling which occurs when retinal capillaries begin to leak. Retinal swelling can blur central vision if it involves the macula. She also looks for neovascularization or new vessels growing from the surface of the retina or optic nerve. These can bleed into the vitreous causing clouding of the vision.

How is diabetic retinopathy treated?
Laser is a very effective treatment for both retina swelling and neovascularization. Visual results however, depend largely on the timing of these treatments. The best way for diabetic patients to protect their vision is with a dilated retinal examination every year.

Can diabetic retinopathy be prevented?
When blood sugar is maintained below 150 at all times the risk of diabetic retinopathy is reduced by 50%. Other factors that may reduce the risk of diabetic retinopathy are blood pressure and lipid control. Daily aspirin may also help to protect the blood vessels.