If you have diabetes mellitus, your body does not use and store sugar properly.  High blood-sugar levels can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain.  The damage to retinal vessels is referred to as diabetic retinopathy.

A medical eye examination is the only way to find changes inside your eye.  An ophthalmologist can often diagnose and treat serious retinopathy before you are aware of any vision problems.  The ophthalmologist dilates your pupil and looks inside of the eye with an ophthalmoscope.

If your ophthalmologist finds diabetic retinopathy, he or she may order color photographs of the retina or a special test called fluorescein angiography to find out if you need treatment.  In this test a dye is injected in your arm and photos of your eye are taken to detect where fluid is leaking.

The best treatment is to prevent the development of retinopathy as much as possible.  Strict control of your blood sugar will significantly reduce the long-term risk of vision loss from diabetic retinopathy.  If high blood pressure and kidney problems are present, they need to be treated.

Laser surgery:
Laser surgery is often recommended for people with macular edema, PDR and neovascular glaucoma.

For macular edema, the laser is focused on the damaged retina near the macula to decrease the fluid leakage.  The main goal of treatment is to prevent further loss of vision.  It is uncommon for people who have blurred vision from macular edema to recover normal vision, although some may experience partial improvement.  A few people may see the laser spots near the center of their vision following treatment.  The spots usually fade with time, but may not disappear.

For PDR, the laser is focused on all parts of the retina except the macula.  This panretinal photocoagulation treatment causes abnormal new vessels to shrink and often prevents them from growing in the future.  It also decreases the chance that vitreous bleeding or retinal distortion will occur.

Multiple laser treatments over time are sometimes necessary.  Laser surgery does not cure diabetic retinopathy and does not always prevent further loss of vision.