The complex pressure gradients in the eye are easily disrupted, potentially predisposing a patient to primary open-angle glaucoma (POAG). Low systolic ocular perfusion pressure (SOPP) may be associated with the condition, and this association may be secondary to low systolic blood pressure (SBP) and high intraocular pressure (IOP), according to a new study published in the British Journal of Ophthalmology.

Researchers in Singapore investigated the relationship between POAG and ocular perfusion pressure (OPP), blood pressure (BP), and IOP profiles in this population-based sample of nearly 10,000 Asian individuals from three ethnic groups in Singapore: Malays, Indians and Chinese. Participants were recruited from the Singapore Epidemiology of Eye Diseases Study and underwent standardized ocular and systemic examinations.

The study enrolled 9,877 participants (19,587 eyes), including 213 POAG cases (293 eyes). Researchers found eyes with the lowest levels of systolic OPP (<110mm Hg) were 1.85x more likely to have POAG compared with eyes with mid-range levels (123-137mm Hg). Investigators consistently found the lowest quartile of systolic BP (<12 mm Hg) was 1.69x more likely to have POAG compared with mid-range SBP levels (138-153mm Hg). Also, researchers noted the effect of lower SBP on POAG was more pronounced in eyes with IOP ≥21mm Hg.

In contrast with previous studies, mean OPP and diastolic OPP were not associated with POAG after adjusting for relevant confounders and IOP, researchers said. Investigators also reported both low and high levels of SOPP were associated with POAG compared with mid-range SOPP levels, suggesting a “U-shaped” association between SOPP and POAG. “Third, low SBP was also associated with POAG and this effect was especially more pronounced among eyes with ocular hypertension, further indicating that identification of concurrent low SBP and ocular hypertension may also be a useful approach in stratifying POAG risk group,” the researchers wrote in their paper.

They concluded, “To date, this is the first population-based study which comprehensively demonstrated that the effect of OPP surrogates on POAG was in part secondary to either high IOP or low SBP. Our findings collectively provided additional clarity on the roles of OPP surrogates and BP profiles in POAG.”