ASK THE DOCTOR

by Paul K. Overland, MD

Artwork:� Medical caduceus

NOTE:� If you have any questions for �Ask the Doctor,� please send them to the VOICE editorial office.

����������� This issue, our column is by Paul K. Overland, MD, an ophthalmologist working at the Rocky Mountain Eye Center, in Missoula, Montana.

Q:� After becoming diabetic, I was afflicted with diabetic retinopathy.� This reduced my vision to 60% of normal in one eye and 10% of normal in the other eye.� Laser surgery has been recommended.� What I want to know is:� How successful is laser surgery?� What are the chances it will, instead, make things worse?� Is this a risk I should take?

A:� My first answer to your question is really a statement of the seriousness of diabetic retinopathy, which is the leading cause of new cases of legal blindness among working-age Americans.� One of our great problems is that type 2 diabetes emerges in adulthood, is frequently undiagnosed for many years, and high blood sugars during this time can cause irreversible damage to the retinal circulation.� Once diabetes has been diagnosed, it is essential to tightly control blood sugars, to prevent continuing damage to the blood vessels throughout the body.

Your question does not state your age or the duration of your diabetes, nor the type of diabetic retinopathy you have.� In general there are two types of diabetic retinopathy, and both can damage or destroy your vision.

The most common form is non-proliferative (�background�) retinopathy in which the tiny blood vessels in the eye develop leaks.� Once the leaking begins, blood and fluid seep into the retina, causing swelling, and fatty material can accumulate within the retina.� Sometimes the fluid accumulates in the retina�s center, called the macula, and the resulting edema causes profound loss of reading vision.� Another cause of permanent loss of clear vision is capillary (small blood vessel) closure, in which blood supply to retinal tissue is stopped and retinal tissue dies.

A more serious type of diabetic retinopathy is called proliferative, and in this case retinal blood vessels become obstructed.� Large areas of the retina lose their source of nutrition and oxygen.� When this happens, the retina tries to build new blood vessels to replace the old damaged ones.� However, the new blood vessels are abnormal.� They do not grow within the retina but rather �proliferate� on the surface of the retina.� This can lead to severe bleeding into the vitreous cavity, followed by scarring and ultimately, retinal detachment.� If this proliferative diabetic retinopathy is not treated promptly, it can cause severe loss of vision and blindness.

Laser surgery can be successful in preventing severe vision loss in proliferative diabetic retinopathy, and this has been proven scientifically over the past 30 years, in many controlled studies.�

Additionally, laser is very useful in preventing visual deterioration in background diabetic retinopathy, where it is used to seal up leaking blood vessels which can cause bleeding and swelling within the retina.

Laser surgery does not ordinarily make the vision worse, but there can be some temporary swelling in the retina following laser treatment.� This ordinarily clears within six weeks� time.� In general, all of our controlled studies on diabetic retinopathy tell us that laser surgery is much safer than and preferable to letting diabetic retinopathy take its natural course, which ordinarily leads to blindness.

You should consult an ophthalmologist, eye MD, who is experienced in retinal laser treatment and diabetic retinopathy.

Your question underscores the need for everyone to have routine eye examinations every two to three years in adulthood to screen for disorders including cataract, glaucoma and diabetic retinopathy.� Individuals diagnosed with diabetes should have such exams once a year.� Eye MD�s (ophthalmologists) are most qualified to diagnose and treat your eye conditions.