Baseline ophthalmic artery blood flow velocities predict structural and functional glaucoma progression after four years

Abstract

Purpose: To examine the retrobulbar blood flow parameters and structural and functional progression in patients with open-angle glaucoma (OAG) over a 4-year period.

Methods: 112 patients with OAG were assessed for retrobulbar blood flow in the ophthalmic (OA) and central retinal (CRA) arteries as measured by color Doppler flowmetry and intraocular pressure (IOP) using Goldmann applanation tonometry at baseline and every 6 months for a 4 year period. Structural disease progression was monitored with optical coherence tomography and Heidelberg retinal tomography and defined as two consecutive visits with RNFL thickness decrease by at least 8% and/or horizontal or vertical cup/disk ratio increase by at least 0.2 compared to baseline. Functional disease progression was monitored with 24-2 SITA visual field exam using the Humphrey visual field machine and defined as 2 consecutive visits with a mean deviation decrease by at least 2 compared to baseline and/or AGIS increase by at least 2 compared to baseline. Two-sample t-tests were used to test for differences in baseline data between patients who progressed and those who did not. A p-value <0.05 was considered statistically significant.

Results: 75 patients showed structural disease progression with a baseline OA peak systolic velocity (PSV) of 24.25 cm/s (SE=0.80) and an OA end diastolic velocity (EDV) of 5.81 cm/s (0.20). 37 patients did not progress structurally and had significantly higher OA PSV and EDV values at baseline. OA PSV for patients who did not progress was 29.11 cm/s (2.18) and OA EDV was 7.19 cm/s (0.51) leading to a significant difference between groups with OA PSV p=0.0242 and OA EDV p=0.0118. 35 patients showed functional disease progression with a baseline OA PSV of 23.42 cm/s (1.34) and an OA EDV of 5.41 cm/s (0.27). 77 patients did not progress functionally and had higher OA PSV and EDV values at baseline. OA PSV for patients who did not progress was 26.96 cm/s (1.18) and OA EDV was 6.65 cm/s (0.29) leading to a significant difference between groups with OA PSV p=0.0307 and OA EDV p=0.0054. There was no significant difference in CRA PSV, CRA EDV, or IOP between those who progressed structurally or functionally and those that did not (p>0.05).

Conclusions: In this cohort of patients with OAG, lower OA blood flow values at baseline were predictive of glaucomatous structural and functional progression after 4 years.

Keywords: 436 blood supply • 464 clinical (human) or epidemiologic studies: risk factor assessment • 610 nerve fiber layer