Breakthrough in Treating Diabetic Eye Disease

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For people with diabetic macular edema, injections of the drug ranibizumab (brand name Lucentis) in combination with laser therapy result in better eyesight than laser therapy alone, according to new government-funded research. Macular edema, which affects nearly 30% of people who have had diabetes for at least 20 years, is a swelling of the portion of the eye responsible for central vision and is a leading cause of blindness in American adults.

Since 1985, the standard treatment for diabetic macular edema has been laser therapy of the retina, the light-sensing structure of the eye that includes the macula. Recent small studies, however, have indicated a benefit to injecting medicines that block vascular endothelial growth factor (VEGF), such as ranibizumab, into the eye. (VEGF is a chemical that stimulates blood vessel growth.)

To determine whether laser therapy, anti-VEGF injections, or some combination of the two is the most effective treatment for diabetic macular edema, researchers evaluated 854 eyes in 691 people who had been diagnosed with Type 1 or Type 2 diabetes and macular edema. Participants were randomly assigned to receive one of four treatments: placebo injections plus prompt (within a week) laser therapy, ranibizumab injections plus prompt laser therapy, ranibizumab injections plus laser treatment administered at least six months later, or injections of the corticosteroid triamcinolone (Trivaris) plus prompt laser treatment.

In general, the treatments continued until each person’s vision improved or retinal thickness returned to normal, or until further treatment did not improve vision or retinal thickness. Injections of ranibizumab could be given once every four weeks; injections of triamcinolone could be given once every 16 weeks.

After one year, almost 50% of the eyes treated with ranibizumab and either prompt or delayed laser therapy had significantly improved vision, represented by the ability to read at least two additional lines on an eye chart. Fewer than 5% of the eyes that had received one of these treatments had a visual loss of two or more lines. Comparatively, roughly 30% of people receiving a placebo injection and laser therapy or a triamcinolone injection with laser therapy could read at least two additional lines on an eye chart, while 13% to 14% of the eyes in these groups had a visual loss of two or more lines.

Participants in each of the three groups that received either ranibizumab or triamcinolone injections and laser treatment experienced decreased retinal thickness compared with people who had received placebo injections along with laser treatment. However, people receiving triamcinolone had more complications such as high eye pressure requiring medicine and cataracts requiring surgery, while those receiving ranibizumab had fewer complications such as eye infection or worsening of a preexisting retinal detachment.

According to Neil M. Bressler, MD, chief of the Retina Division at the Wilmer Eye Institute, Johns Hopkins University, “These results indicate a treatment breakthrough for saving the vision of people with diabetic macular edema. Eye injections of ranibizumab with prompt or deferred laser treatment should now be considered for patients with characteristics similar to those in this clinical trial.” A physician from the National Eye Institute noted that ranibizumab represents the first new treatment for diabetic macular edema “in a quarter of a century.”

Ranibizumab is not approved by the Food and Drug Administration for the treatment of diabetic macular edema, but it is approved for age-related macular degeneration, so doctors may prescribe it off-label for macular edema.

Researchers will be following the participants for at least three years to obtain further information about the safety and the long-term effectiveness of the various treatments.

To learn more, read the articles “Diabetic Macular Edema: Ranibizumab Injections Plus Laser Therapy Results in Dramatic Visual Improvement” or “A Genetech Eye Treatment Is Found to Help Prevent Vision Loss in Diabetics,” or see the study’s abstract in the journal Ophthalmology.

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