- Corticosteroids Improve Vision in Diabetics With Macular Edema
Results from a two-year clinical trial at the University of Sydney in Australia further establish the drug triamcinolone acetonide, a corticosteroid, as a promising treatment for people with diabetic macular edema.
Following an injection of the drug into the eye of 4 mg of triamcinolone, 19 eyes (in 34 patients) showed a five-letter improvement on a standard eye chart, compared with only nine eyes treated with a placebo. The average improvement was 5.7 letters. The drug also reduced the thickness of the macula. Benefits of the drug lasted up to two years with repeated treatment.
The standard treatment for macular edema is laser photocoagulation, a procedure that closes the new blood vessels with a laser. But the treatment only improves vision in about 10% of cases. Researchers believe that the drug triamcinolone may block the growth and movement of cells necessary for forming new blood vessels. And the drug may prevent leakage by conserving the tight spaces between cells in the blood vessel walls.
The treatment isn’t without complications, however -- specifically, the development of cataracts and elevation of intraocular pressure, although the researchers say these are manageable with surgery and other drugs. They are conducting an additional clinical trial combining laser treatment with triamcinolone. Results from this study were reported in the journal Ophthalmology (Volume 113, page 1533).
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New Drug Stems Blood Vessel Growth in Diabetic Retinopathy
In proliferative diabetic retinopathy -- when new blood vessel growth blocks vision -- the best treatment has been photocoagulation, using lasers to close new blood vessels. Three small studies now suggest that the drug bevacizumab (Avastin), which blocks the activity of a protein that increases blood vessel growth, may be safe and effective.
In the largest study of 45 eyes in 32 patients, the drug reduced blood vessel leakage completely or in part within a week of injection. Leaking had not recurred at an 11-week follow-up in all but one case. One concern: At the largest drug dose, the fellow eye was affected, suggesting the drug was affecting the patient’s entire system, not just the treated eye. Lower doses of the drug did not have that effect.
In a smaller study of three patients, blood vessel growth halted within one to three weeks of injection. And in a study of seven eyes in five patients who had blood vessel growth in the iris after photocoagulation, growth halted after one week of treatment, although two eyes needed a second injection later. These studies were reported in Ophthalmology (Volume 113, page 1695) and in the American Journal of Ophthalmology (Volume 142, page 685).
