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A gospel truth in ophthalmology has been that people of African ancestry are more likely to develop glaucoma, but a new study clouded the picture.

The long-term cohort study has identified modifiable risk factors for conversion from suspect glaucoma to primary open-angle glaucoma (POAG) and found that systemic hypertension may protect against progression from incipient to more advanced disease.

The findings, presented at the 2025 annual meeting of the American Glaucoma Society, come from the ongoing [OKAY?] Primary Open-Angle African American Glaucoma Genetics study. Patients (N = 330) were followed for an average of 6.7 years, in which time 45 (13.6%) progressed to POAG.

“Our study identified three independent risk factors for conversion from glaucoma suspect to POAG in individuals of African ancestry: Elevated intraocular pressure [IOP], absence of hypertension, and presence of myopia,” Aaron Zhao, a medical student at the Scheie Eye Institute, University of Pennsylvania, in Philadelphia, who presented the data, told Medscape Medical News.

In a univariate analysis, an elevated IOP ≥ 21 mm Hg carried a hazard ratio (HR) of 2.48 for development of glaucoma (P = .003). Other risk factors on univariate analysis were absence of hypertension (HR, 1.92; P = .03), family history of glaucoma (HR, 1.85; P = .13), and diabetes (HR, 1.54; P = .15).

Myopia emerged as a risk factor in the multivariate analysis, with almost a 2.5 times greater risk (HR, 2.35; P = .03), whereas elevated IOP (HR, 2.49; P = .01) and absence of hypertension (HR, 2.4; P = .02) carried similar risks.

‘Somewhat Unexpected’ Finding

The finding about the potential protective effect of hypertension was “somewhat unexpected,” Zhao said, but aligns with emerging evidence of U-shaped relationships between blood pressure and glaucoma.

“While hypertension has traditionally been considered a risk factor for glaucoma, our results suggest that mild to moderate hypertension might actually be protective in some cases, potentially by ensuring adequate perfusion pressure to the optic nerve,” he said.

Other research has shown people of African ancestry may have lower blood flow behind the eye and reduced vascular density in the back of the eye when compared to people of European heritage.

“This could predispose them to reduced optic nerve perfusion, making the relationship between systemic blood pressure and glaucoma particularly important in this population,” Zhao said. “Additionally, patients with diagnosed hypertension may have better controlled blood pressure and more regular medical monitoring compared to those without diagnosed hypertension, who might experience unrecognized blood pressure fluctuations that could affect optic nerve perfusion.”

The finding warrants further investigation into the “complex relationship” between systemic blood pressure and glaucoma pathogenesis in the study population, Zhao added. “The approach to managing blood pressure in glaucoma suspects may need to be more nuanced than previously thought,” he said.

Myopia and Elevated IOP Warrant Watching

The new data reinforce the message that eye specialists “should be watching patients with elevated eye pressure very closely, especially if they are myopic,” Jeffrey Henderer, MD, a professor of ophthalmology at Temple University in Philadelphia, said.

Henderer noted the overall rate of conversion to POAG was not significantly different from 9.5% figure reported in the Ocular Hypertension Treatment Study observation group.

“These study populations had a different racial mix, implying that perhaps African Americans aren’t at dramatically higher risk for converting to glaucoma than other racial groups,” he said.

However, Henderer said he struggled to explain the potential protective effect of hypertension in the study population. “Could the patients be incorrect? If the data was drawn from patients’ recollection of their diseases, that could lead to inaccuracies,” he said. “Could the patients have their hypertension being treated with beta-blockers, which might lower eye pressure and perhaps be protective? I don’t know.”

Henderer noted only 37 patients made it to 4000 days of follow-up, and only seven of them did not have hypertension. “That is a pretty small sample size and I wonder if that is causing some sort of sampling error that responsible for this finding,” he said.

This study was independently supported. Zhao and Henderer reported no relevant financial disclosures.

Richard Mark Kirkner is a medical journalist based in Philadelphia.