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Higher mean blood pressure (BP) levels were associated with faster rates of visual field progression in patients with glaucoma, according to a retrospective cohort study.

Among 985 patients, the interaction terms of higher mean BP and higher standard deviation of BP were associated with faster annual mean deviation changes for both mean arterial pressure (0.02 dB/year per 1-mm Hg higher, P=0.001) and diastolic arterial pressure (0.02 dB/year per 1-mm Hg higher, P<0.001), reported Robert N. Weinreb, MD, of the University of California San Diego, and colleagues.

In addition, the interaction term of higher standard deviation of BP and higher mean intraocular pressure (IOP) was associated with faster annual mean deviation changes for both mean arterial pressure (0.01 μm per 1-mm Hg higher, P=0.003) and diastolic arterial pressure (0.01 μm per 1-mm Hg higher, P=0.001), they wrote in .

"These findings suggest that long-term BP variability may be a modifier of IOP as a risk factor for glaucomatous progression," Weinreb and team noted.

Angelo P. Tanna, MD, of Northwestern University Feinberg School of Medicine in Chicago, who wasn't involved in the study, told MedPage Today that both high and low BP are linked to glaucoma.

"We believe that hypertension and abnormally low blood pressure lead to impaired blood flow to the optic nerve, making that tissue more susceptible to glaucoma damage," he said. "Early in the hypertensive disease process, high blood pressure may cause [more] blood flow to the optic nerve. As the process advances, damage to blood vessels may then result in impaired optic nerve blood flow in those same patients."

Tanna praised the new study, saying there's "every reason" to trust it.

"The occurrence of higher levels of blood pressure variability inherently indicates those subjects experienced more substantial highs and lows," he noted. "It makes sense that optic nerve perfusion would be more severely compromised at times in subjects with higher BP variability."

Tanna also said it's important to encourage patients to adhere to prescribed doses of antihypertensive medications to avoid variations in BP that could boost glaucoma, especially at night, in light of nighttime drops in BP and worsening glaucoma. "I advise primary care physicians that, when possible, it's preferable from a glaucoma perspective to avoid nighttime dosing of medications to lower BP."

He added that patients whose glaucoma worsens despite seemingly well-controlled IOP can undergo 24-hour BP monitoring on an ambulatory basis. He cautioned, however, that it's not clear if lowering blood pressure reduces glaucoma risk.

In regard to specific BP medications, Tanna said calcium channel blockers are linked to less BP variability, but some studies link their use to worsening glaucoma.

Louis B. Cantor, MD, of the Indiana University School of Medicine in Indianapolis, told MedPage Today that it's somewhat surprising that higher mean BP is linked to glaucoma, since research has tended to highlight the harm from low BP.

Cantor said ophthalmologists should consider measuring BP in the clinic. "If we notice irregularities or fluctuation in blood pressure, we may then refer those patients to their primary care physician and involve them in discussions about whether blood pressure intervention may be indicated."

For this study, Weinreb and colleagues used longitudinal data on patients with suspected or confirmed glaucoma who were selected from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. Patients underwent BP and visual field testing from November 2000 to December 2022.

Of the 985 adult patients -- and 1,674 eyes -- included in the study, mean age was 61.2, 57.2% were women, 61.7% were white, and 32.6% were Black. Mean BP was 131.6/76.1 mm Hg, and the mean rate of visual field mean deviation change was -0.13 dB/y over a mean follow-up of 8 years.

The researchers noted limitations to their study, such as variations in BP throughout the day, the lack of continuous BP monitoring, and the lack of information on use of antihypertensive medications.

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