Black people are six times more likely than non-Hispanic white people to lose significant eyesight from glaucoma, even when they have similar access to healthcare, researchers say.
Glaucoma also starts earlier on average in the lives of Black people than in the lives of non-Hispanic white people, and so screening for glaucoma in Black people should be more frequent, said Jae Hee Kang, ScD, an assistant professor of medicine at Brigham and Women’s Hospital in Boston, Massachusetts.
She and colleagues published their analysis of a large database of healthcare professionals in Translational Vision Science and Technology. “That takes away some of the extraneous socioeconomic factors which may influence any disparities that you might observe in studies like this,” she told Medscape Medical News.
The researchers analyzed nearly 210,000 participants from two cohorts of the Nurses’ Health Study (one enrolled from 1980-2018 and the other from 1989-2019), and from the Health Professionals Follow-up Study (enrolled from 1986-2018).
Participants were older than age 40, none had glaucoma at baseline, and their data was collected during comprehensive eye exams. In biennial follow-ups, participants updated information on their lifestyle, diet, and medical status, including glaucoma diagnosis.
When the participants reported a glaucoma diagnosis, the researchers asked permission for their medical records or a glaucoma questionnaire, including all visual field data. They zeroed in on 2564 eyes in 1946 people with incident primary open angle glaucoma (POAG).
Using artificial intelligence, a computer identified 14 patterns. Four of these “archetypes” represented advanced loss patterns, nine early loss, and one no visual field loss. “It really seems to be a heterogenous disease,” Kang said. “This is one way of subtyping.”
Black participants made up 1.3% of the study. They had double the risk of the early visual field loss archetypes compared with non-Hispanic white participants (hazard ratio [HR] 1.98; 95% CI, 1.48 – 2.66). And they had six times the risk for advanced loss archetypes (HR, 6.17; 95% CI, 3.69 – 10.32).
The differences in risk for early and advanced visual field loss between non-Hispanic White people on one hand and Asian people (who made up 1.2% of the participants) or Hispanic people (who made up 1.1%) on the other hand were not statistically significant.
In some of the archetypes, participants appeared to lose central rather than peripheral vision. “We’re not sure why, but we observed that the people who seemed to get the central vision loss have a lower capacity for blood flow,” Kang said.
This pattern of central vision loss was more common among Black and Hispanic participants than among non-Hispanic White participants.
The elevated risk of visual field loss among the Black participants was particularly striking because access to healthcare has been identified as one of the factors explaining racial and ethnic disparities in health. “What we were surprised about is that these were all health professionals who were getting eye exams and they were presenting with advanced risk of loss,” said Kang.
Even after adjusting their statistical models for the frequency of eye exams, the difference between Black and non-Hispanic White participants persisted. The researchers adjusted for many other potential risk factors as well, including socioeconomic status, glaucoma family history, body mass index, blood pressure, diabetes, and physical activity.
The patterns of visual field loss were similar between eyes of the same patients, which the researchers said indicated genetics and environmental exposures played a part in the development of the visual field loss. Previous research has also associated genetically determined African ancestry with greater glaucoma risk.
Another potential reason for the differences between Black people with glaucoma and non-Hispanic White people could be stress, Kang said. “It could be systemic racism, and the weathering through life, marginalization, and discrimination. We weren’t able to capture all of those factors.”
In their next steps, the researchers hope to gain more insight into such specific risk factors, and to see whether the disease progression can be predicted by genes, said Kang.
The study largely confirms what previous research had found about the elevated risk of glaucoma for Black people, said Leon Herndon, MD, chief of the glaucoma division at Duke University in Durham, North Carolina, who was not involved with this research.
“We all need to be invigorated,” he said. “Maybe we need to think about different screening strategies to allow patients easier access.”
The small representation of Asian, Hispanic, and Black people in the sample underscores the need for studies with more diverse populations, he said.
The study was supported by the National Eye Institute, Research to Prevent Blindness, and The Glaucoma Foundation (LRP). Kang and Herndon reported no relevant financial relationships.
Transl Vis Sci and Technol. July 2022 issue. Full text
Laird Harrison writes about science, health and culture. His work has appeared in national magazines, in newspapers, on public radio and on websites. He is at work on a novel about alternate realities in physics. Harrison teaches writing at the Writers Grotto. Visit him at www.lairdharrison.com or follow him on Twitter: @LairdH