Black Glaucoma Patients Have More Visual Field Variability Than White Patients

By Lisa Rapaport

June 09, 2021

(Reuters Health) - Visual field is more varied among Black patients with primary open-angle glaucoma than their white counterparts, a difference that may help partially explain racial disparities in glaucoma detection and outcomes, a new study suggests.

Researchers examined data from evaluations of 1,103 eyes from white individuals and 428 eyes from 317 Black individuals. They assessed standard automated perimetry (SAP) mean deviation values for each eye over time, then examined the association of race with the standard deviation (SD) of the residuals from the trend lines.

For white individuals, the mean number of visual fields was 7.4 and the mean rate of mean deviation change was -0.25 dB/year after a mean follow-up period of 8.1 years. For Black individuals, the mean number of visual fields was 6.9 and the mean rate of mean deviation change was -.20 dB/year after a mean follow-up period of 8.7 years. The difference in the mean rates of mean deviation change was not statically significant.

The SD of the residuals from trend lines was larger among Black individuals (1.53 dB), however, compared with white individuals (1.26 dB), suggesting Black patients had greater visual field variability.

"These findings may contribute to worse clinical outcomes that are often seen in Black patients," Dr. Felipe Medeiros, a professor of ophthalmology at Duke University in Durham, North Carolina, and colleagues conclude in the British Journal of Ophthalmology. Dr. Medeiros didn't immediately respond to requests for comment.

Socioeconomic status was associated with visual field variability, and the difference between Black and white individuals was greater at lower incomes, the analysis found.

Researchers also simulated several scenarios of disease progression based on data on visual field variability and found it would take much longer to detect progression in Black individuals.

In one example, researchers looked at patients with baseline mean deviation of -10 dB and moderate progression of -0.5 dB/year. If these patients had annual testing, it would take 12.7 years to detect progression in 80% of Black individuals compared with 9.8 years for white individuals, the researchers estimate.

One limitation of the study is that it was done at a single center, and results might not be generalizable to outcomes elsewhere, the authors not. In addition, race was self-reported.

Another drawback of the study is that visual field examination is one of several inputs, including intra ocular pressure, optic nerve and optical coherence tomography that should be assessed, said Dr. Karen Allison of New York Ophthalmology Associates in New York City.

"One should not use progression as the only factor in aggressively treating patients, especially in Black and Hispanic patients that have the highest burden of blindness from this disease and more variability in their visual field testing," Dr. Allison, who wasn't involved in the study, said by email.

Despite the limitations of a retrospective review of data from a single eye center, the findings are still troubling, said Dr. Nicole Ross, OD, an associate professor of optometry at the New England College of Optometry in Boston who wasn't involved in the study.

"These findings are certainly of concern to all clinicians," Dr. Ross said by email. "Further study is certainly warranted to better understand the contributing factors and solutions for mitigation."

SOURCE: British Journal of Ophthalmology, online May 13, 2021.