Understanding Diabetes and the Eye
Diabetes is one of the leading causes of blindness in the United States. High levels of sugar in the blood cause damage to the blood vessels in the retina, the nerve layer that covers the back of the eye. These damaged blood vessels can leak and cause vision loss, sometimes sudden and severe. At its worst, diabetic eye disease can result in new, abnormal blood vessel growth, severe glaucoma, retinal detachment and total blindness. It is extremely important for all diabetics to have at least yearly eye exams by an ophthalmologist to identify these potential problems early. Your ophthalmologist will dilate your eyes to view your retina in detail to determine if there is evidence of diabetic retinopathy. Additional testing may also be considered if diabetic retinopathy is found.
Non-Proliferative Diabetic Retinopathy
Non-Proliferative Diabetic Retinopathy or NPDR is the earliest form of diabetic retinopathy. NPDR occurs when small vessels called capillaries are damaged by elevated blood glucose over time. Damage to these small vessels creates areas of weakness in the wall of the vessels leading to hemorrhaging inside the retina called intraretinal hemorrhages and formation of small outpouchings in the vessel wall called microaneurysms. Intraretinal hemorrhages and microaneurysms are the hallmark of NPDR.
Proliferative Diabetic Retinopathy
Proliferative diabetic retinopathy or PDR is an advanced stage of diabetic retinopathy where new abnormal blood vessels form in the retina and vitreous. This process is called neovascularization. These new blood vessels are fragile and bleed easily leading to hemorrhages in the retina and vitreous. These hemorrhages cause scar formation, which eventually can lead to retinal detachment and severe vision loss. It is important to identify PDR early so treatment can be initiated before severe vision loss has occurred.
Diabetic Macular Edema
Microaneurysms leak fluid into the retina causing swelling and deposits to form called exudates. Diabetic macular edema or DME results when this process affects the central retina called the macula, which is responsible for detailed central vision. Fluid accumulation in macula can lead to symptoms of blurred vision, visual distortion, dark spots or a feeling that colors are washed out (decreased contrast). If you experience any of these symptoms early evaluation and treatment are needed to limit permanent vision loss.
Diabetic Eye Disease Treatment
The most important treatment for diabetic eye disease is prevention. Tight control of blood sugar and blood pressure are the keys to reducing your risk of developing diabetic retinopathy. If diabetic retinopathy is found at your screening exam we may recommend special testing to evaluate the extent of the disease with a test called an OCT which is able to provide a microscopic type view of the retina similar to the way a CT or MRI scan images your other body parts. A special dye study called fluorescein angiography may also be obtained to evaluate the health of the blood vessels in the back of the eye. If diabetic retinopathy is significantly affecting vision, treatment with laser, eye injections or surgery may be necessary to improve vision or at least prevent or slow further vision loss.
In some cases medications injected directly into the vitreous cavity may be recommended to treat both diabetic macular edema and proliferative diabetic retinopathy. Medications called anti-vascular endothelial growth factors or anti-VEGF are helpful in blocking the chemicals released by the diseased retina that promote leakage and the formation of abnormal new blood vessels (neovascularization). Several injections may be required to achieve the desired result and may be combined with laser treatments such as focal laser or pan retinal photocoagulation.
Focal Laser Photocoagulation
Focal laser photocoagulation is a laser surgery procedure used to treat leaking blood vessels in diabetic macular edema. In this treatment a low powered laser is applied to areas of leakage to seal the leaking blood vessels and prevent further leakage. With time and healing after laser treatment further macular edema is halted and often improves resulting in better vision.
Pan Retinal Photocoagulation (PRP)
In the advanced form of diabetic retinopathy called proliferative diabetic retinopathy (PDR), the diseased retina releases factors that cause new abnormal blood vessels to grow (neovascularization) and will eventually lead to severe vision loss if left untreated. The standard treatment for PDR is pan retinal photocoagulation or PRP. In this laser surgical treatment, laser energy is applied to the peripheral retina to eliminate the abnormal blood vessels and prevent further neovascularization. The central portion of the retina is left untreated to preserve central vision.