To compare pulsatile ocular blood flow measurements in untreated ocular hypertensive (OHT) subjects and primary open-angle glaucoma (POAG) patients.

A prospective observational study in an institutional setting.

A total of 97 subjects were recruited to the study (50 ocular hypertensives, 24 glaucoma patients, and 23 normal subjects). “High-risk” OHT had intraocular pressure (IOP) > 25 mm Hg; “low-risk” OHT had IOP ≤ 25 mm Hg.

Pulsatile ocular blood flow (POBF) measurements were made with a pneumotonometer in sitting, standing, and supine positions. Intraocular pressure was measured with Goldmann tonometry. Twenty-six patients were started on topical treatment to reduce intraocular pressure, and the measurements were repeated at a review visit.

Untreated POAG patients and high-risk OHT had reduced POBF (P < .001) and pulse volume (P < .001) compared with both normals and low-risk OHT. Women had higher POBF than men (P = .009, two-way analysis of variance). Subjects with pharmacologically lowered IOP had a significant increase in mean POBF (+80.9 μl/min, P = .02) and a significant reduction in mean arterial blood pressure (−11.0 mm Hg, P = .003). Postural reduction in POBF (from sitting to supine) increased and became statistically significant in POAG and OHT subjects on treatment (P < .0001).

High-risk ocular hypertensives have reduced POBF when compared with low-risk ocular hypertensives and normals and do not differ significantly from POAG patients. Our findings support the clinical impression that ocular hypertensive subjects with IOP of over 25 mm Hg should be monitored closely and may benefit from prophylactic treatment to lower intraocular pressure.