(dailyRx News) One of the biggest concerns for diabetes patients is vision loss. While steroids and laser treatment can help when eye problems get severe, medications may offer clearer results.
Between 40 to 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy, an eye disease that damages blood vessels in the retina, according to the National Eye Institute. If the disease progresses, it can lead to a more serious condition called macular edema.
A new study found that two medications may provide the most consistently effective treatment for some patients.
John Alexander Ford, MD, of Norwich Medical School at the University of East Anglia in the UK, led a systematic review of 51 articles about 29 studies concerning diabetic macular edema and therapies, and summarized their findings.
The macula is the part of the eye where sharp, straight-ahead vision occurs, and edema means swelling. With some diabetes patients, fluid leaks into the macula, causing it to swell and vision to blur.
Scientists have discovered that a protein called vascular endothelial growth factor-A (VEGF-A) is a major contributor to the inflammatory process in macular edema.
In evaluating the different studies, the authors found that anti-VEGF medications proved to be consistently effective in the short term. Specifically, ranibizumab (trade name Lucentis) and bevacizumab (trade name Avastin) were highlighted for successfully controlling macular edema without producing major unwanted side effects.
Dr. Ford told dailyRx News, "The anti-VEGFs are a significant advance in the treatment of diabetic macular edema. The mainstay of treatment for diabetic macular edema has been laser, which can only halt progression, whereas anti-VEGFs give patients the chance to improve their vision. However, only about half of patients treated with anti-VEGFs will see an improvement."
Bevacizumab was originally developed to treat colorectal cancer, and ranibizumab was created from bevacizumab to be used specifically for the eye.
Ranibizumab is considerably more expensive than bevacizumab, according to the authors. The estimated cost of ranibizumab is $2,000 per dose compared with $50 for bevacizumab. Otherwise, scientists noted no difference between the drugs in terms of effectiveness.
The authors evaluated laser treatment, which has been effective in preserving vision but has been less successful in restoring it, once lost.
They also looked at results from steroid therapy, including dexamethasone (brand name AK-Dex, Ocu-Dex), fluocinolone (brand name Retisert) and triamcinolone (brand name Triesence, Trivaris Intravitreal).
The researchers concluded that steroid treatment has mixed success and, almost uniformly, steroids have increased the incidence of cataracts and intraocular pressure.
Dr. Ford and his colleagues also commented that adding laser therapy to anti-VEGFs did not appear to confer additional benefit, based on the short-term data available.
“The anti-VEGF drugs appear to be a significant advance in the treatment of diabetic macular edema, and are regarded now as the treatment of choice for patients affected by this condition,” concluded the authors. “Despite the current wider spectrum of treatments for diabetic macular edema, only a small proportion of patients recover good vision, and thus the search for new therapies to prevent and manage diabetic macular edema needs to be continued.”
Dr. Ford told dailyRx News, "In terms of future research, there is an urgent need for a head-to-head trial of bevacizumab versus ranibizumab. Research is still needed to find the optimum dose regime of the anti-VEGFs."
The study was published March 1 in BMJ Open, an open access, online-only general medical journal. The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.