A new treatment can reverse a common cause of vision loss in patients with diabetes, researchers reported this week at a U.S. National Eye Institute conference.

Researchers with the Diabetic Retinopathy Clinical Research Network found that that eye drug Lucentis works better than laser treatment alone to treat diabetic macular edema. The findings are published in the journal Ophthalmology.

The finding could help the 3 million Canadians with type 1 or type 2 disease, since between 40 and 45 per cent will develop some stage of diabetic retina damage.

"For the first time in 25 years, we have definitive proof that a new treatment can lead to better results for the eye health of people with diabetes," said Dr. Neil M. Bressler, who oversaw the study.

"We expect the results of this study to have a major impact on how ophthalmologists treat macular edema in people with diabetes," he said.

Diabetic macular edema is a condition in which fluid caused by leaking blood vessels builds up near the centre of the retina. For decades, the standard treatment has been to use a laser to remove the overgrowth of tiny vessels that impair vision.

This study found that nearly 50 per cent of patients given eye injections of Lucentis along with laser treatments showed improvement in vision after a year of treatment, compared to just over a quarter of patients treated with laser alone.

Lucentis, known generically as ranibizumab, is an engineered product called a monoclonal antibody that is derived from the cancer drug Avastin. The newer biologic is already used to treat macular degeneration, the leading cause of blindness in the elderly that's caused by blood vessel growth in the retina.

For the study, researchers tested 691 patients with diabetic macular edema. They randomly received either laser treatment alone, laser plus Lucentis or laser plus another drug, a corticosteroid called Trivaris (triamcinolone). (Some had both eyes tested for a total of 850 eyes treated). The patients receiving Lucentis injections had eight or nine injections over the course of a year.

The researchers found that those in the Lucentis treatment group showed greatly improved results, with no serious side-effects.

"After one year, nearly 50 per cent of eyes treated with ranibizumab and prompt or deferred laser treatment showed a substantial visual improvement," they wrote.

Only 28 per cent of patients treated with laser alone or with triamcinolone saw this improvement. Patients treated with injections of the corticosteroid Trivaris and laser showed no greater improvement in vision than patients treated with laser alone.

Those patients who saw improvements with Lucentis reported they could read at least two additional lines on an eye chart, or letters that were one-third smaller than could be recognized before treatment. Most of the improvement was seen after two months of injections.