Latanoprost eye drops were shown to preserve visual field in patients with open-angle glaucoma in a relatively short time, and the benefits grew with longer treatment, according to a study published online December 18 in the Lancet.
The study is the first randomized placebo-controlled trial to evaluate the vision-preserving effect of an intraocular pressure-lowering drug, write David F. Garway-Heath, MD, from the National Institute for Health Research Biomedical Research Centre, London, United Kingdom, and colleagues. The authors randomly assigned 516 patients newly diagnosed with open-angle glaucoma at ten UK centers to receive either 0.005% latanoprost or placebo eye drops once daily between December 1, 2006, and March 16, 2010.
They found that patients in the treatment group experienced significantly longer visual field preservation compared with those in the placebo group (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.28 - 0.69; P = .0003).
"The results of the [United Kingdom Glaucoma Treatment Study] give clinicians greater confidence in recommending the treatment to patients because there is now top-level evidence for the extent to which intraocular pressure-lowering with latanoprost preserves vision compared to placebo," Dr Garway-Health told Medscape Medical News. "As there was a placebo arm, it was possible to follow the natural, untreated, history of the condition."
The researchers conducted visual field testing, intraocular pressure measurement, and imaging during 11 scheduled visits over the course of 24 months during the triple-masked trial.
Within 24 months, 94 of the 461 patients (231 in the treatment group and 230 in the placebo group) in the final analysis experienced visual field loss consistent with progression of glaucoma. Of those 94 patients, 59 were in the placebo group and 35 were in the latanoprost group.
The percentage of patients who experienced visual field loss after 12 months came to about 5% for the treatment group, about half of the placebo group. The difference was also evident at 18 months, and at 24 months, the gap widened to ~20% vs ~30%.
Of 192 adverse events that occurred during the trial, researchers attributed none to the study drug.
"Latanoprost is the most widely prescribed drop to lower intraocular pressure in the developed economies, and since it came off patent in 2011, probably, worldwide," Dr Garway-Heath said.
The new trial results confirm previous trial results, "which confirms that many glaucoma patients progress at very slow rates, even untreated," he said. "The implication of this is that some low-risk patients could be monitored without treatment, [with] these patients thus avoiding the burden of unnecessary treatment."
"The results of the study also show that it is possible to identify glaucomatous visual field deterioration during quite short periods, provided visual field tests are performed with sufficient frequency. Frequent testing is unlikely to be cost-effective if undertaken for all glaucoma patients, but individuals considered high-risk would benefit from more...frequent tests," he added. "The implication of this is that clinical trials can be much shorter, reducing development costs of new drugs and increasing the likelihood of new treatments being brought forward for patient benefit."
In an accompanying comment, Anders Heijl, MD, PhD, professor and chair of the Department of Ophthalmology, Lund University, Skåne University Hospital, Malmö, Sweden, writes that the study "is important in many ways, perhaps most importantly because it is the second to show the positive treatment effects of intraocular pressure reduction in manifest glaucoma.... That the study was placebo controlled is a further strength."
"I think it's great that they've proven something that we've been assuming all along," Shuchi Patel, MD, assistant professor of ophthalmology at Loyola University Stritch School of Medicine in Maywood, Illinois, and a glaucoma expert, told Medscape Medical News. "It would've been kind of shocking if we found that lowering pressure in what we consider our gold standard of therapy actually was not preserving visual function and probably would have devastated the world of glaucoma."
She continued, "I think it just continues practice. If anything, it's probably great for physicians to quote this data to patients and say it's been proven. It could help the patients continue their medication."
This research was funded by Pfizer and the UK National Institute for Health Research Biomedical Research Centre. Nine coauthors and the commentator have reported various financial relationships with several companies or organizations; the other coauthors and Dr Patel have disclosed no relevant financial relationships.
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Cite this: Glaucoma Drug Shows Visual Preservation Over 2 Years - Medscape - Dec 24, 2014.