Treatment Not Always Needed to Prevent Vision Loss From High Eye Pressure

By Lorraine Janeczko

April 28, 2021

NEW YORK (Reuters Health) - Not all patients with elevated intraocular pressure (IOP) need pressure-reducing treatment to prevent glaucoma-related vision loss, according to new data from a large twenty-year cohort study.

"With only 25% of the individuals in the study developing vision loss in one or both eyes after all these years, we know now that not all of those patients needed to be treated," lead study author Dr. Michael A. Kass of Washington University School of Medicine in St. Louis, Missouri, said in a press release.

"We suggest that clinicians use the risk model to stratify patients at low risk, most of whom can probably be followed without treatment. Patients at high risk should be examined more often and may benefit from preventative treatment," he advised in an email to Reuters Health.

In the randomized, controlled Ocular Hypertension Treatment Study (OHTS), Dr. Kass and his colleagues enrolled 1,636 participants who averaged around 55 years of age and had ocular hypertension, at 22 medical centers. The researchers followed the cumulative incidence and severity of primary open-angle glaucoma (POAG) over twenty years.

In phase 1 of the study, from 1994 to 2002, participants received either topical ocular hypotensive medication or close observation. In phase 2, from 2002 to 2008, both groups received medication, with treatment no longer governed by study protocol from 2009. In phase 3, from 2016 to 2019, participants received ophthalmic examinations and visual function tests.

In phase 3, the researchers collected data after 20 years of follow-up, or within two years of death. Overall, 483 participants (30%) developed POAG in one or both eyes, the team reports in JAMA Ophthalmology.

After adjusting for exposure time, the twenty-year cumulative incidence of POAG in one or both eyes was 46% in all participants, 49% in those who were only observed, and 42% in those who received medication. The twenty-year cumulative incidence of POAG was 55% in Black/African Americans and 43% in those of other races.

At 20 years, the overall cumulative incidence of visual field loss among study participants was 25%.

"These findings provide evidence to support better decision-making by patients in collaboration with their doctors," said Dr. David S. Friedman of Massachusetts Eye and Ear and Harvard Medical School, in Boston.

"The findings align with the group's earlier findings that delaying treatment for those with high eye pressures who would have been eligible for this study does not dramatically affect long-term prognosis, and that patients have different risks based on factors that can be measured," he told Reuters Health by email.

"This is an exceptionally well-conducted study," said Dr. Friedman, who was not involved in the work. "That said, loss to follow-up is inevitable in such a study. Nearly one-third of participants died, and overall, about 60% of those who were eligible participated in this round of evaluations. We do not know if participants and non-participants had the same rate of disease development, so the estimates may have some bias."

"This is the third phase of a series of studies that are arguably the most influential in the field of glaucoma," Dr. Erin A. Boese, an ophthalmologist at the University of Iowa Carver College of Medicine, in Iowa City, told Reuters Health by email. "This series of studies guides my practice more than any other glaucoma study to date, and I am certain to incorporate the results of this most recent installment into how I care for my patients moving forward."

"The meticulous and careful protocol, which adds to the beauty of the study and gives one confidence in the results, can also make it difficult to translate the results into everyday clinical care," she added. "It is important for patients and physicians to realize that this (46%) risk applies to patients regularly followed by an eye care provider, and doesn't account for people who decide not to seek care."

"Lowering eye pressure isn't always easy or benign," Dr. Boese, who also was not involved in the study, explained. "Drops can be irritating, difficult to instill, expensive, and still may not be effective enough. Surgery comes with its own risks. It is so important that we don't needlessly treat patients on the basis of one number or data point."

"Like glaucoma, high eye pressure doesn't mean the same thing for everyone. For chronic life-long diseases like ocular hypertension and glaucoma, knowing when not to treat is sometimes just as important as knowing when to treat," she added.

The study received no commercial funding. The authors, as well as Drs. Friedman and Boese, report no conflicts of interest.

SOURCE: JAMA Ophthalmology, online April 15, 2021.