Diabetic Retinopathy

Lakshmana Kooragayala, M.D. – Retina Specialist

Diabetic Retinopathy Diagnosis and Treatment

If you have diabetes mellitus, your body does not use and store sugar properly. High blood sugar levels can damage blood vessels in the retina, the back lining of the eye. The retina is like the film in an old camera. Therefore, any damage to the retina can adversely affect vision. The damage to retinal blood vessels is referred to as diabetic retinopathy.

Types of Diabetic Retinopathy

There are two types of diabetic retinopathy:

• Nonproliferative diabetic retinopathy (NPDR) or background retinopathy
• Proliferative diabetic retinopathy (PDR)

Nonproliferative Diabetic Retinopathy

NPDR is an early stage of diabetic retinopathy. Many people with diabetes have mild NPDR, which usually does not affect vision. However, there are two forms of NPDR that can cause vision loss:

• Macular edema: swelling of the macula, a small area in the center of the retina that allows us to see fine details clearly in the center of our vision. The swelling is caused by fluid leaking from retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral vision continues to function.
• Macular ischemia: occurs when small blood vessels in the macula close. Central vision blurs because the macula no longer receives sufficient blood supply to work properly.

Proliferative Diabetic Retinopathy

PDR is present when abnormal new vessels (neovascularization) begin growing on the surface of the retina. PDR may cause more severe vision loss than NPDR because it can affect both central and peripheral vision. The new, abnormal blood vessels do not resupply the retina with normal blood flow. The new vessels can bleed and cause scar tissue, which can adversely affect retinal function. Proliferative diabetic retinopathy causes visual loss in the following ways:

• Vitreous hemorrhage: The fragile new vessels may bleed into the vitreous, a clear, gel-like substance that fills the center of the eye. If the vitreous hemorrhage is small, a person might see only a few new dark floaters. A very large vitreous hemorrhage might block out all vision. It may take days, months or even years to resorb the blood, depending on the amount of blood present.
• Traction retinal detachment: When PDR is present, scar tissue associated with neovascularization can shrink, wrinkling and pulling the retina from its normal position. Macular wrinkling can cause central visual distortion. More severe vision loss can occur if large areas of the retina are detached or torn off the back of the eye.

Diabetic Retinopathy Diagnosis

A Marietta Eye Clinic physician will dilate your eyes and look inside at the retina with an instrument called an ophthalmoscope. If diabetic retinopathy is found, you may undergo a special test called a flourescein angiography to find out if you need treatment. In this test, a dye is injected into your arm and photos of your eye are taken to see where the retinal vessels are leaking.

Treatment for Diabetic Retinopathy

The best treatment is to prevent the development of retinopathy as much as possible. Strict control of your blood sugar will significantly reduce the long-term risk of vision loss from diabetic retinopathy. Other treatments include:

• Laser surgery: For macular edema, the laser is focused on the swollen, damaged retina near the macula to decrease fluid leakage. The main goal of treatment is to prevent further vision loss. It is uncommon for people who have blurred vision from macular edema to recover normal vision, although some may experience partial improvement. For PDR, the laser is focused on all parts of the retina except the macula. This treatment, called panretinal photocoagulation, causes abnormal new vessels to shrink and prevents them from growing in the future. It also decreases the chance that vitreous bleeding or retinal distortion will occur.
• Vitrectomy: In advanced PDR or vitreous hemorrhage that doesn’t clear, your doctor may recommend a vitrectomy. During this microsurgical procedure, the blood-filled vitreous is removed and replaced with a clear solution. Vitrectomy often prevents further bleeding by removing neovascularization that caused the bleeding. If the retina is detached, it can be repaired during vitrectomy surgery

Vision Loss is Largely Preventable

If you have diabetes, it is important to know that with improved methods of diagnosis and treatment only a small percentage of people who develop retinopathy have serious vision problems. Early detection of diabetic retinopathy is the best protection against loss of vision. You can significantly lower your risk of vision loss by maintaining strict control of your blood sugar and visiting your ophthalmologist regularly.

When to Schedule an Examination

People with diabetes should schedule examinations at least once a year. More frequent eye exams may be necessary after a diagnosis of diabetic retinopathy has been made. Pregnant women with diabetes should schedule an appointment during the first trimester because retinopathy can progress quickly during pregnancy.