Combination Drug-Laser Therapy Shows Great Promise in Treating Diabetic Retinopathy
Clinical studies at 52 different sites nationwide have shown that combining standard laser treatments with injections of the drug ranibizumab (Lucentis) offers substantially better results for treating macular edema than laser treatments alone. The research showed that almost 50 percent of patients treated with the combination therapy showed substantial improvement in their vision after one year, compared with 28 percent of patients who had been treated solely with laser.
Diabetes patients often experience macular edema-the swelling and leaking of small blood vessels in the retina-as an effect of the inflammatory high blood sugar levels brought on by their disease. Complications from the condition can include gradual loss of sharpness of vision, and at their most extreme, total loss.
Laser treatments, which have been a standard therapy for the past 25 years, use intensely focused beams of light to seal leaking blood vessels and forestall the damage that they can cause to the retina. Currently, diabetes researchers have focused on developing drugs to block the chemical signal that stimulates the growth of blood vessels, which in people with diabetes tend be weak and leaky. Repeated injections of a drug like ranibizumab seem to counter the leakage.
The study, conducted by the Diabetic Retinopathy Clinical Research Network (DRCR.net), and supported by the National Eye Institute and the National Institute of Diabetes and Digestive and Kidney Diseases, tracked treatment results on 854 eyes among 691 type 1 and type 2 patients with macular edema who had either one eye or both eyes treated. The patients, whose average age was in the early 60s, were randomly placed in four groups:
- Sham injections followed by prompt (within a week) laser treatments
- Ranibizumab injections followed by prompt (within a week) laser treatments
- Ranibizumab injections followed by laser treatments deferred six or more months
- Injections of triamcinolone followed by prompt (within a week) laser treatment. (Triamcinolone is a corticosteroid, a naturally or artificially produced steroid hormone that, when administered as a drug, is used to treat inflammation.)
The researchers continued treatment until the patients' vision or retinal thicknesses returned to normal or there was no further improvement in either condition. At the end of a year, they found that 50 percent of eyes that had been treated with a combination of ranibizumab and either prompt or delayed laser treatment could read at least an additional two lines on an eye chart. In the groups that received the combination drug-laser therapy, less than 5 percent of the eyes treated experienced a decline in visual acuity.
In the groups that received either laser treatment plus a sham drug, or a combination of laser and triamcinolone, a little less than 30 percent showed improved vision that allowed them to read at least two additional lines on an eye chart. About 13 percent of eyes in those two groups experienced a decline in visual acuity of two or more lines on the chart.
All participants who received injections of either ranibizumab or triamcinolone experienced a greater decrease in retinal thickness than members of the group that received only laser treatment. However, participants who took triamcinolone had a greater rate of complications. Thirty percent of people in that group developed high internal eye pressure that required medications, and 60 percent developed cataracts that had to be treated surgically.
The Diabetic Retinopathy Clinical Research Network is planning to monitor study participants for three years to see what risks or side effects the combination ranibizumab-laser therapy may create.
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