A cheaper drug for a common eye disease called wet macular degeneration is just as effective as a more expensive one, a new study has found.

Vision improvement was the same among patients given monthly shots of Avastin or Lucentis for one year, the study found.

Avastin was originally developed to prevent blood vessel growth that enables cancerous tumors to spread. But when it was discovered to be effective in AMD treatment, many doctors began using it "off-label." Avastin costs about $50 per treatment compared to $2,000 for Lucentis.

While the study found that Avastin is as effective as Lucentis in improving vision, it also showed higher rates of serious side effects in the Avastin group, including effects that required hospitalization; 24 per cent of patients in the Avastin group experienced side effects compared with 19 per cent in the Lucentis group.

The study was not able to determine whether the adverse events and treatment were linked; that requires more study, the authors say.

AMD is the leading cause of vision loss and blindness in older Americans. In its advanced stages, the wet form spurs the growth of abnormal blood vessels, which leak fluid and blood into the macula and obscure vision. Because AMD causes a loss of central vision, many patients are unable to drive, read, or perform tasks that require hand-eye coordination.

For this study, almost 1,200 AMD patients with a median age of 80 were treated. Patients were randomly assigned to one of four regimens for a year: Lucentis, either monthly or when the disease was showing symptoms, or Avastin, either monthly or during symptoms.

Vision improvement was virtually identical for either drug when given monthly. And when each drug was given on an as-needed schedule, there also was no difference between drugs. The as-needed dosing schedule meant four to five fewer injections per year than monthly treatment. There was less improvement with vision in those taking the drug on an as-needed basis, rather than as a monthly treatment but overall visual results were still excellent.

Results were published online Thursday by the New England Journal of Medicine and will be presented at a meeting on Sunday.