Diabetic Eye Disease

Diabetes can affect the eyes primarily by causing retina and lens problems. That is why it is important to examine the eyes of diabetics at least once a year and more frequently if mild or moderate findings are discovered. 

To use the analogy of a camera, the retina is like the traditional film in a camera (in the past when we used film instead of digital) and diabetic retinopathy can result. A cataract occurs when the normal lens becomes cloudy, much like the lens in a camera when it becomes smudged or damaged. But the lens can also change shape in diabetes which leads to a change in focus and prescription without developing a cataract.

Diabetic retinopathy comes in two forms: (1) diabetic retinopathy or (2) diabetic macular edema. 

(1) Diabetic retinopathy occurs when there is ischemia (poor blood flow) from damaged capillaries in the retina, which can be mild or severe. The body responds to the poor blood flow with changes in the retina. In the bad or proliferative form of diabetic retinopathy, abnormal blood vessels develop (called neovascularization) which can, if not detected on exam and treated in time, lead to vitreous blood (bleeding inside the cavity of the eye) that can block vision or tractional retinal detachment (scar bands pulling the retina off of inside wall of the eye). Treatment may consist of laser spots applied using a microscope/laser beam device to the ischemic retina with poor blood flow. Or, injection of tiny amounts of medications (anti-vascular endothelial growth factor, [anti-VEGF]) through the sclera (white wall of the eye) may help the abnormal capillaries to get better or go away altogether. 

(2) Clinically significant diabetic macular edema occurs when the abnormal capillaries near the center of vision (macula) leak fluid. The fluid causes the macula to swell and may leave deposits of protein and lipid that can distort the vision much like bad film in a camera can distort the photograph that one takes. Generally, if the macular edema is bad enough, injection of the anti-VEGF medication mentioned earlier for diabetic retinopathy is the preferred treatment. 

We have special cameras and laser scanning devices (optical coherence tomography or OCT with angiography capability) to evaluate and diagnose diabetic retinopathy or diabetic macular edema.

Diabetic Cataracts:  For lens problems related to diabetes, one can get swelling of the lens due to high concentrations of sugar drawing in excess water into the lens. This can result in a change in one’s glasses prescription. However, this is usually temporary. As the blood sugar gets under control, the glasses prescription usually changes back to normal. So it is important to keep the blood sugar under control through medication and exercise. 

If a cataract develops in a diabetic, it tends to be the posterior subcapsular kind (cloudiness of the center-back part of the lens) rather than in the nucleus [center-mid portion] as usually occurs if it is age-related. Cataract surgery is performed as typical, but if a patient has diabetic retinopathy, that may get a little worse after cataract surgery, so one has decide whether some kind of treatment needs to be performed before or after cataract surgery to lower the risk.

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