A New Standard of Care for Patients with Diabetic Macular Edema
By A.Paul Chous, MA, OD, FAAO
Diabetic Macular Edema (DME) occurs when the tiny capillaries serving the macula—the central area of the eye’s light-sensitive retina that allow detailed, color vision—leak fluid resulting in tissue swelling, damage to the cells of the retina, and loss of vision. Patients with significant DME typically will have difficulty performing everyday visual tasks such as reading, driving, and distinguishing faces. DME is the most common, serious eye complication resulting from diabetes, with about 100 thousand cases in the United States each year. In the 1980s, a groundbreaking clinical trial called the Early Treatment of Diabetic Retinopathy Study (ETDRS) showed that prompt laser therapy of severe DME cut the odds of significant, permanent vision loss in half. Ever since that time, laser treatment has been used to help preserve the sight of tens of thousands of Americans with diabetes. While a 50% reduction in risk is impressive, it means that many patients with DME still experience significant vision loss despite laser therapy.
Over the last fifteen years, a number of newer therapies have been developed and tested to try to improve results obtained with laser treatment alone. These treatments include topical (eye drop) steroidal and non-steroidal anti-inflammatory medications, steroid injections into the eye, time-released steroid implants that are surgically implanted into the eye, and, more recently, injection of so-called anti-VEGF medications such as Avastin, Macugen, and Lucentis. VEGF is an acronym for ‘vascular endothelial growth factor,’ an inflammatory protein released by damaged cells within the retina that promotes fluid leakage. Anti-VEGF drugs act to block the effects of VEGF on retinal capillaries.
So should anti-VEGF therapy be part of the new standard of care for patients with DME? A recent study supported by the National Eye Institute, a division of the National Institutes of Health, compared the effectiveness of the anti-VEGF medication, Lucentis (ranibizumab), against standard laser therapy for patients with type 1 and type 2 diabetes and a diagnosis of DME. This study included a total of 854 eyes of 691 people, who had one or both eyes treated. They were randomly assigned to one of four study groups: sham injections plus prompt laser treatment within one week; Lucentis injections plus prompt laser treatment; Lucentis plus deferred laser treatment after six months or more; or injections of steroid medication known as triamcinolone plus prompt laser treatment.
At the end of a year, 50% of patients who received Lucentis in addition to any laser therapy experienced substantial improvement in their ability to read the eye chart (at least two lines smaller than they could prior to treatment), whereas only 30% of patients receiving laser alone or a combination of steroid plus laser showed such improvement. Patients receiving steroid treatment had higher rates of serious complications, like increased eye pressure requiring medication (30%) or development of cataract requiring surgery (60%), whereas complications from treatment with Lucentis were rare. Specifically, the study found that injections of Lucentis were not associated with any serious risks such as heart attack or stroke (see my previous dLife article titled “Can Medication for Severe Retinopathy Lead to Stroke?”). Researchers will continue to monitor the study participants for at least three years to obtain additional information about the safety and effectiveness of these macular edema treatments.
"These results indicate a treatment breakthrough for saving the vision of people with diabetic macular edema," said Neil M. Bressler, M.D., chief of the Retina Division at the Wilmer Eye Institute at Johns Hopkins University. “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."
Lucentis still costs about one hundred times as much Avastin (bevacizumab), another anti-VEGF medicine that has been more widely used by retinal specialists for precisely this reason. What we now need is a head-to-head comparison of these two medicines for the treatment of patients with DME. Stay tuned.
For more information on diabetic eye disease, consult Dr. Chous’ book Diabetic Eye Disease: Lessons From a Diabetic Eye Doctor, Fairwood Press, Seattle, 2003.
Read more about Dr. Chous here.
Visit Dr. Chous' website here.
NOTE: The information is not intended to be a replacement or substitute for consultation with a qualified medical professional or for professional medical advice related to diabetes or another medical condition. Please contact your physician or medical professional with any questions and concerns about your medical condition.
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