Diabetic retinopathy - How is DME treated?


Image caption : Diabetes and Eye Damage: The retina, the delicate, light-sensitive membrane lining the back of the eyeball, may be damaged by diabetes. This is called retinopathy. In the first stage of retinal damage, called nonproliferative retinopathy, the tiny capillaries that feed the retinal tissue balloon out into pouches, called microaneurysms. This is a direct result of damage to the endothelial cells that line the vessels of the retina. Capillaries leak, and many close off, resulting in a decreased flow of blood to the retina called ischemia.

Ischemia causes the formation of abnormal new vessels. These new vessels grow in an irregular pattern and can cause bleeding into the eye, swelling of the macula (a critical area of the retina necessary for sight), and scarring, which can cause the retina to detach. The presence of these abnormal blood vessels is called proliferative retinopathy. Diabetes is the leading cause of blindness in the US in people under the age of 65, with 12,000-24,000 new cases each year.

Diabetes also increases the risk of developing cataracts and glaucoma. Cataracts, the clouding of the eye's lens, develop at an earlier age in people with diabetes. Glaucoma is an increase in fluid pressure inside the eye that leads to optic nerve damage. Someone with diabetes is twice as likely to get glaucoma as someone who doesn't have diabetes.

How is DME
treated?

DME can be treated with several therapies that may be used alone or in combination.

Anti-VEGF Injection Therapy. Anti-VEGF drugs are injected into the vitreous gel to block a protein called vascular endothelial growth factor (VEGF), which can stimulate abnormal blood vessels to grow and leak fluid. Blocking VEGF can reverse abnormal blood vessel growth and decrease fluid in the retina. Available anti-VEGF drugs include Avastin (bevacizumab), Lucentis (ranibizumab), and Eylea (aflibercept). Lucentis and Eylea are approved by the U.S. Food and Drug Administration (FDA) for treating DME. Avastin was approved by the FDA to treat cancer, but is commonly used to treat eye conditions, including DME.

The NEI-sponsored Diabetic Retinopathy Clinical Research Network compared Avastin, Lucentis, and Eylea in a clinical trial. The study found all three drugs to be safe and effective for treating most people with DME. Patients who started the trial with 20/40 or better vision experienced similar improvements in vision no matter which of the three drugs they were given. However, patients who started the trial with 20/50 or worse vision had greater improvements in vision with Eylea.

Most people require monthly anti-VEGF injections for the first six months of treatment. Thereafter, injections are needed less often: typically three to four during the second six months of treatment, about four during the second year of treatment, two in the third year, one in the fourth year, and none in the fifth year. Dilated eye exams may be needed less often as the disease stabilizes.

Avastin, Lucentis, and Eylea vary in cost and in how often they need to be injected, so patients may wish to discuss these issues with an eye care professional.

The two images were taken before (Top) and after anti-VEGF treatment (Bottom).

The two images were taken before (Top) and after anti-VEGF treatment (Bottom).
The retina of a person with diabetic retinopathy and DME, as viewed by optical coherence tomography (OCT). The two images were taken before (Top) and after anti-VEGF treatment (Bottom). The dip in the retina is the fovea, a region of the macula where vision is normally at its sharpest. Note the swelling of the macula and elevation of the fovea before treatment.

Focal/grid macular laser surgery. In focal/grid macular laser surgery, a few to hundreds of small laser burns are made to leaking blood vessels in areas of edema near the center of the macula. Laser burns for DME slow the leakage of fluid, reducing swelling in the retina. The procedure is usually completed in one session, but some people may need more than one treatment. Focal/grid laser is sometimes applied before anti-VEGF injections, sometimes on the same day or a few days after an anti-VEGF injection, and sometimes only when DME fails to improve adequately after six months of anti-VEGF therapy.

Corticosteroids. Corticosteroids, either injected or implanted into the eye, may be used alone or in combination with other drugs or laser surgery to treat DME. The Ozurdex (dexamethasone) implant is for short-term use, while the Iluvien (fluocinolone acetonide) implant is longer lasting. Both are biodegradable and release a sustained dose of corticosteroids to suppress DME. Corticosteroid use in the eye increases the risk of cataract and glaucoma. DME patients who use corticosteroids should be monitored for increased pressure in the eye and glaucoma.

National Eye Institute (NEI)/ National Institutes of Health (NIH)



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