Diabetic Retinopathy
Diabetic retinopathy is an eye condition that can develop in people with diabetes. It happens when high blood sugar levels harm the small blood vessels in the retina, the part of the eye that senses light and helps you see. Over time, this damage can affect your vision and, if not treated, may eventually lead to blindness.
The early form of this disease is called non-proliferative or background diabetic retinopathy. It involves small hemorrhages (spots of blood) and small out-pouched blood vessel walls (microaneurysms) that can lead to swelling in the central retina. This is known as a macular edema.
As the duration of diabetes continues, particularly when blood sugar is poorly controlled, diabetic retinopathy eventually leads to loss of blood vessels and damage to nerve tissue in the retina. If the disease progresses, the part of the retina that has inadequate blood flow produces a molecule called a vascular endothelial growth factor (VEGF) that leads to new blood vessel formation from pre-existing blood vessels. Although this may sound like a form of healing, the new blood vessels are abnormal and grow into the gel of the middle of the eye (vitreous). These new blood vessels are fragile and may leak fluid or bleed. This stage of the disease is called proliferative diabetic retinopathy, since new blood vessels are multiplying.
Adults who are newly diagnosed with diabetes should have an exam to rule out retinopathy, since the body is often diabetic years before the diagnosis is made. Childhood onset diabetes can typically wait 5-10 years before an initial exam, since retinopathy rarely develops before the 10-year duration of the disease.
Before
After
Above demonstrates neovascularization of the disc (arrow), neovascularization from the supero-temporal retinal capillaries (arrowhead), and dot-and-blot hemorrhages with some exudates
Diabetic Retinopathy Treatment
The goal of treatment is to maintain good vision and prevent permanent vision loss from chronic swelling, lack of blood flow, or retinal detachment. Good blood sugar control, healthy diet, and exercise are critical to prevent progression and worsening of the disease.
Non-proliferative diabetic retinopathy is treated when a macular edema is present by using office lasers that target microaneurysms, injections that block VEGF, and anti-inflammatory medications. Lasers and injections are typically repeated for a period of time until the macular edema resolves.
Before
After
2 months following PASCAL pan-retinal photocoagulation, the neovascularization is regressing, and laser scars demonstrate early pigmentation (arrow)
Proliferative diabetic retinopathy is treated with office lasers, injections, and sometimes surgery. In the early stages of proliferative diabetic retinopathy, laser treatment called panretinal photocoagulation is performed to improve oxygen levels and decrease the demand for oxygen that causes new blood vessel growth.
If bleeding occurs in the middle part of the eye, a vitreous hemorrhage results that blocks light and can cause floaters, leading to a significant decrease in vision. This form of the disease is treated with injections and lasers. It may eventually require surgery if the blood does not reabsorb over a reasonable period.
With long-standing severe diabetic retinopathy, new blood vessels growing into the vitreous can contract and form scar tissue that leads to mechanical separation of the retina from its underlying skin layer. This is called a traction retinal detachment and is treated with surgery to remove scar tissue and allow the retina to settle back into its natural position.
Traction retinal detachment is a severe form of proliferative diabetic retinopathy that usually has a significant underlying lack of blood flow. While surgery can correct the scar tissue component, most patients will have some permanent vision loss based on the reduced level of blood flow to the central retina and other factors. Diabetic macular edema and proliferative diabetic retinopathy are often present together and must both be treated to attempt to preserve vision.