Diabetic retinopathy occurs when high blood sugar damages the blood vessels supplying oxygen to the retina. This leads to retinal damage and decreasing vision.
Anyone with diabetes is at risk for developing diabetic retinopathy. The longer a person has diabetes, the greater their chance of developing diabetic retinopathy. It is the leading cause of blindness in working-aged adults in the United States.
Diabetes damages the retina in two ways. The first, known as non-proliferative diabetic retinopathy, occurs when the blood vessels of the retina begin to bleed or leak fluid. This results in retinal swelling (macular edema), small hemorrhages, and the formation of deposits known as exudates.
The second way that diabetes damages the retina is known as proliferative diabetic retinopathy. This is a more severe type of retinal damage. It occurs when blood vessels in the retina or optic nerve become blocked, consequently starving the retina of necessary nutrients. In response, the retina grows new blood vessels (neovascularization). Unfortunately these new vessels are abnormal, causing bleeding or formation of scar tissue.
Proliferative diabetic retinopathy may lead to any one of the following:
- Vitreous hemorrhage – the new vessels bleed profusely into the eye, blocking vision.
- Retinal detachment – scar tissue pulls on the retina, causing it to tear or detach.
- Neovascular glaucoma – abnormal blood vessels block drainage of fluid out of the eye, causing high eye pressure.
Diabetic retinopathy is diagnosed with a dilated exam of the retina by an ophthalmologist. The ophthalmologist may wish to study the retinal blood vessels with photographs or by using a test called fluorescein angiography. During this test, a dye is injected into the arm and quickly travels throughout the blood system. Once the dye reaches the blood vessels of the retina, a photograph is taken of the eye. The dye allows the ophthalmologist to detect damaged blood vessels as they leak into the retina.
The best way to prevent diabetic retinopathy is through strict control of blood sugar and blood pressure. These measures significantly reduce the risk of long-term vision loss. With annual eye exams and prompt treatment of diabetic retinopathy, few people progress to serious vision loss.
In the early stages of diabetic retinopathy, the blood vessels in the eye leak, causing swelling of the retina. For decades, this swelling has been treated with retinal laser, which has been shown to slow the progression of vision loss. Recently, ophthalmologists have also been injecting anti-leakage medicines into the eye. These medicines include steroids such as triamcinolone acetate and anti-vascular endothelial growth factors (anit-VEGF) such as bevacizumab or ranibizumab. In combination with laser, these injections have been shown to reduce retinal swelling and improve vision loss. Some of these medicines have side-effects, however, so the decision to receive an injection should be discussed with your doctor.
Thanks to recent advances in retinal imaging (Optical Coherence Tomography), we are learning much more about the pathophysiology of diabetic retinopathy. Nationwide clinical studies are underway to determine the best combination of laser and injections for treatment of this disease (DRCR.net). Pharmaceutical companies are also working to create longer lasting injections with lower side-effect profiles.
The Bascom Palmer Eye Institute advantage
The 30 clinical faculty members at the Bascom Palmer Eye Institute have accumulated years of clinical experience in the management of diabetic retinopathy. Drs. Harry Flynn and William Smiddy have been active in diabetic retinopathy clinical studies for more than 18 years. At the request of the American Academy of Ophthalmology, Drs. Flynn and Smiddy organized a 350-page monograph titled Diabetes and Ocular Disease: Past, Present and Future Therapies. Diabetic patients also have a number of non-retinal abnormalities including increased rates of cataract, glaucoma, ocular muscle abnormalities, corneal diseases, and susceptibility to infection. The faculty at the Bascom Palmer Eye Institute are familiar with these potential complications and have experience in the management of these problems when they occur.