Effect of Changes in Arterial Blood Pressure on Optic Nerve Head Blood Flow Regulation in Patients with Primary Open Angle Glaucoma

Abstract

Purpose : It has been speculated that patients with primary open angle glaucoma (POAG) show abnormal optic nerve head blood flow (ONHBF) autoregulation, although direct experimental evidence for this hypothesis is sparse. The aim of the present study was to compare ONHBF as assessed with laser Doppler flowmetry (LDF) during isometric exercise between patients with POAG and a healthy control group.

Methods : Forty patients with POAG and 40 age- and sex-matched healthy controls were included in this study. To increase arterial blood pressure, three periods of handgripping were performed, each period lasting for 2 minutes. ONHBF was measured continuously using LDF. Ocular perfusion pressure (OPP) was calculated out of mean arterial blood pressure and intraocular pressure.

Results : Isometric exercise induced a significant increase in OPP during all handgripping periods in both groups (p < 0.001), while no change in ONHBF was observed in either of the two groups. In a subgroup of two healthy subjects and three POAG patients, ONHBF showed a consistent decrease of more than 10% during handgripping, although arterial blood pressure increased. This difference between groups was not significant (p = 0.61). In addition, four other POAG patients showed a consistent increase in ONHBF of more than 10% during isometric exercise, whereas this was not observed in healthy controls (p= 0.035).

Conclusions : ONHBF autoregulation seems to be more often abnormal in patients with POAG than in healthy control subjects. The association to the disease process is currently unknown and requires further investigation.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.