Sometimes an older and cheaper drug beats the shiny, newer competition by being just as effective for a fraction of the cost. But it takes a lot of time and money to prove it.

A government-sponsored study released yesterday compared Lucentis, a drug approved to treat a common form of blindness in the elderly called macular degeneration, to Avastin, a cancer drug eye doctors have been using to treat the eye disease for years.

It found that patients who got Avastin could read an average of 8 more letters on an eye chart after a year - while Lucentis patients were able to read 8.5 more letters after a year of treatment.

“Health care providers and payers worldwide will now have to justify the cost of using ranibizumab [Lucentis,]” said an editorial accompanying the study in the New England Journal of Medicine.

As we reported before, getting the trial going took years and was pretty complicated, since drug companies are loathe to pay for these kinds of head-to-head studies. It highlights the challenges the government faces in doing comparative effectiveness research.

But since Avastin costs about $50 a pop, while Lucentis costs $2,000, results like this suggest Medicare could save a bundle if people choose the cheaper option.

About 1.75 million people in the U.S. have macular degeneration, but before you get too excited, the drug is used to treat those with the wet form of the disease — only about 15 percent of that population.

Genentech, which makes both drugs, told the New York Times on Thursday that it still believes that Lucentis is safer and better. It’s better at drying the fluid in the eye that is believed to cause the vision loss, and the trial showed it was associated with slightly fewer serious complications.

However, the authors of the study said there weren’t enough patients in the trial to draw conclusions about safety. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.