Diabetic Eye Problems

Clinical Course

The retinal changes of DM are readily seen through an ophthalmoscope. As in other locations such as the kidneys and legs, the hyperglycemia of diabetes damages small blood vessels in the retina. The first evidence of this damage is called nonproliferative retinopathy, seen as small red bulges in the vessels called microaneurysms. With time, less oxygen is delivered to the retina as a result of this vascular damage, and some areas of the retina may infarct. Patients may notice no change in vision during this early stage, although some visual acuity may be lost if the damage involves the macula, the area of the retina responsible for the sharpest vision. New vessels grow in the retina to compensate for insufficient oxygen levels. This proliferative retinopathy can be seen on ophthalmologic examination as an overabundant number of small vessels. These new vessels can result in irreversible vision loss in two ways. They are fragile and prone to rupture, causing hemorrhage and scarring. These vessels can also contract and cause retinal detachment. In addition to retinopathy, diabetics are also more likely to get cataracts and glaucoma than the general population.

Screening, Prevention, Treatment

Because the damage is often irreversible by the time a person notices visual impairment, screening for diabetic retinopathy is important in the care of any diabetic patient. The American Diabetes Association (ADA) recommends that newly diagnosed type 2 diabetics receive a comprehensive dilated eye examination by an ophthalmologist at the time of diagnosis and then yearly thereafter. Type 1 diabetics should receive yearly eye examinations beginning three to five years after diagnosis and not usually before age 10. More frequent examinations are necessary if retinal damage is discovered.

Good glycemic control, as measured by blood glucose and hemoglobin A1c levels, is important in preventing the progression of diabetic retinopathy and preserving vision. Treating high blood pressure in diabetics, with drugs such as β-blockers or angio-tensin-converting enzyme (ACE) inhibitors, has also been shown to slow the progression of retinopathy. Once retinopathy is seen on ophthalmologic examination, early treatment is necessary to prevent further loss of visual acuity. Standard treatment is laser photocoagulation, in which a laser is used to close or destroy the abnormal retinal vessels that are prone to rupture. While this procedure will not restore any vision that has already been lost, it has been shown to slow further vision loss. In the case of extensive damage or retinal detachment, a vitrectomy is performed, a surgical procedure in which the scar tissue and cloudy bloody fluid in the eye are removed. In the case of detachment, retinal reattachment can also be performed during a vitrectomy, although this is successful in only about half of cases.

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