23 Jul Why Diabetics Need to Get Eye Exams
Whether or not you are newly diagnosed or a veteran of diabetes, you need to get your eyes checked at least once a year.
Recommendations by the ADA and the AAO are that every diabetic get a complete eye exam, including a dilated exam (pupils get dilated) to allow proper examination of the retina.
If you are newly diagnosed, you may have noticed blurry vision recently. Large fluctuations of your serum glucose (blood sugar) can change the water content of your lens and cause transient blurry vision. Most likely, since diagnosis, your blood glucose is now lower than it has been in a long time; changing the water content of your natural lens. The refractive power of the eye is now changed and it changes the power of the glasses or contact lenses that you may need.
We are most concerned about diabetic changes in the retina. Most diabetics (over 80%) will develop some degree of diabetic retinopathy in their lifetime. The most common stage of diabetic retinopathy is the so-called “background” or “non-proliferative” phase. Doctors are looking for signs of swelling near the macula, the functional center of the retina. The goal is to prevent swelling in the macula and thus preserve vision. If macular edema has already developed, the goal is to treat the retina with laser or sometimes medicines, to reduce the amount of swelling. This may lead to better vision. Sometimes the gest we can do is to simply limit additional swelling.
Unfortunately, diabetics can NOT self monitor themselves. It is better not to wait for changes in the vision before seeking medical attention. In a perfect world, it is ideal if a patient is still 20/20, yet needs treatment. The chances of preserving the perfect vision are better than trying to regain lost vision.
About 20% of patients that have developed diabetic retinopathy progress to the prolifertive phase of the disease. In this phase, abnormal blood vessels develop on the surface of the retina and other parts of the eye. This retinal neovascularization can cause hemorrhaging into the vitreous and cause significant loss of vision. More importantly, a diabetic retinal detachment can occur. The neovascularization (aka “neovascularization elsewhere”) can grow on the retina surface much like ivy on the forest floor. It can grow from one point to another and start to contract. This pulling on the retina can lead to retinal detachment if not caught in time. This is the mechanism by which diabetics go blind.
The treatment for proliferative diabetic retinopathy is panretinal photocoagulation, that is, diffuse laser photocoagulation to the peripheral or side vision. Proliferative diabetic retinopathy occurs when the retina is “ischemic.” To say another way, ischemia results when the demand for oxygen is greater than the supply. In this state, a growth factor is produced by the retina causing abnormal proliferation of blood vessels. Laser photocoagulation, in this setting, is aimed at “killing” or reducing the need for oxygen in the peripheral or side retina. When the demand for oxygen is reduced sufficiently, the growth factor is no longer produced causing regression of the abnormal blood vessls. The proliferative phase the disease is now stabilized.
Advanced cases may require vitrectomy surgery.
What does this mean to you? Regardless of the number of years that you have been diabetic, make sure you get a dilated eye exam at least annually. Vision does not correlate with the severity of the disease, nor does the disease correlate with sugar control (you can be well controlled, but still suffer from diabetic retinopathy). We, as eye doctors, do a much better job at treating you early and preventing vision loss than vice versa.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist