November is Diabetes Awareness Month, and despite the advances in diabetic eye care that have been made during the past 30 years, diabetic retinopathy remains the leading cause of blindness in the working age population in the industrialized world. The personal and economic costs related to this disorder are staggering, and only increasing in significance as the cases of diabetes reach epidemic proportions.

An estimated 18 million to 21 million Americans have diabetes, about 6 million to 7 million of whom remain undiagnosed and therefore are unaware that they have the disease. And almost 50 percent of patients with diabetes have diabetic retinopathy.

Diabetes remains the leading cause of blindness from age 21 to 65. Indeed, clinical signs of diabetes frequently present themselves through a routine eye examination. Although diabetic retinopathy is a major cause of vision loss, timely detection and management with therapy can significantly reduce this risk in many patients. The American Academy of Ophthalmology recommends that every patient with diabetes has a dilated comprehensive eye examination at least once a year, and sometimes more frequently to allow for detection and management of this disease.

There are two forms of the disease: nonproliferative retinopathy and proliferative retinopathy.

In the nonproliferative form, edema, or fluid, in the retina often causes vision loss. The treatment of this condition includes focal laser therapy and, in severe cases, injections of a steroid drug into the vitreous space of the eye.

In the proliferative type, bleeding into the vitreous gel can occur and panretinal photocoagulation (a laser to the entire peripheral retina) is needed to quiet the disease. This is the more severe type and is often seen in uncontrolled diabetics.

In some instances, the proliferative type progresses to a tractional retinal detachment for which surgery is needed. There is a drug now available, called Avastin, however, that has been shown in recent studies to improve the proliferative form of diabetic retinopathy.

In all cases of diabetes, the ultimate treatment is good blood sugar control. We recommend patients have their Hemoglobin A1C level drawn every three months. We suggest a recommended level no higher than 6.5 percent. This corresponds to an average blood sugar under 130 mg/dl over the previous three months.

If you have diabetes, you should not only be monitoring your blood sugar at home in a daily log, but you should also know the level of your last hemoglobin test.

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Ophthalmologists Drs. Nigel H. Timothy and Adam P. Beck maintain a practice in North Andover and Londonderry, N.H. They are on staff at the Massachusetts Eye and Ear Infirmary and the Joslin Diabetes Center in Boston.