British researchers led by David Garway-Heath, of the Moorfields Eye Hospital and UCL Institute of Ophthalmology in London, tracked outcomes for more than 500 people newly diagnosed with open-angle glaucoma -- the most common form of the disease and one of the leading causes of blindness.
About 45 million people worldwide have this type of glaucoma, and the number is expected to rise to 53 million by 2020 and 80 million by 2040, according to the researchers.
However, they found that the use of latanoprost -- a form of prostaglandin analogue eye drops -- reduced the risk of vision loss in these patients by more than 50 percent over two years, compared to those who received an inactive placebo.
The study, published Dec. 18 in The Lancet, received funding from drug maker Pfizer.
"Medication to lower raised eye pressure has been used for decades as the main treatment for open-angle glaucoma to delay progressive vision loss," Garway-Heath said in a journal news release. "But, until now, the extent to which the most frequently prescribed class of pressure-lowering drugs (prostaglandin analogues) have a protective effect on vision was not known," he said.
"Our findings offer solid proof to patients and practitioners that the visual deterioration caused by glaucoma can be reduced using this treatment," Garway-Heath added.
Two experts in eye health said the study offers reassurance to patients.
Dr. Mark Fromer is an ophthalmologist at Lenox Hill Hospital in New York City. He said that glaucoma is typically treated by interventions that lower the level of pressure within the eye.
"Elevated eye pressure can lead to optic nerve damage," which can harm vision, Fromer explained, so glaucoma "is most commonly treated with a prostaglandin analogue eye drop to reduce eye pressure."
The new study shows "that the use of these medications can greatly reduce the risk of visual loss, and a significant benefit in the treatment group could be seen at one year," he added.
Another expert agreed. "Prostaglandin analogues are typically the first line in treatment for most glaucoma patients as they are an easy, once-a-day medication with a low side-effect profile," said Dr. Reena Garg, assistant professor at the New York Eye and Ear Infirmary of Mount Sinai in New York City.
But Garg also stressed that these medications are not a cure for glaucoma.
In glaucoma, "visual loss can only be slowed, not stopped," Garg said. "It is necessary to educate patients that while glaucoma cannot be cured, proper follow up with a trained specialist can slow the progression of the disease allowing patients to maintain good vision throughout their lifetime."
The U.S. National Eye Institute has more about glaucoma.