Lower ophthalmic artery blood flow velocities predict functional and structural glaucoma progression after 5 years

Abstract

Purpose: To examine the retrobulbar blood flow parameters and functional and structural progression in patients with open-angle glaucoma (OAG) over a 5-year period.

Methods: 112 OAG patients (Mean age 65 yr; 44 male) were assessed for retrobulbar blood flow in the ophthalmic (OA), central retinal (CRA), nasal (NPCA) and temporal (TPCA) posterior ciliary arteries as measured by color Doppler flowmetry at baseline and every 6 months for a 5-year period. 76 patients (Mean age 70 yr; 31 male) were assessed at 5-year follow-up. Functional disease progression was monitored with 24-2 Swedish Interactive Thresholding Algorithm visual field exam using the Humphrey visual field machine and defined as 2 consecutive visits with mean deviation decrease ≥2 and/or Advanced Glaucoma Intervention Study increase ≥2 compared to baseline. Structural progression was monitored with optical coherence tomography and Heidelberg retinal tomography and defined as two consecutive visits with Retinal Nerve Fiber Layer thickness decrease ≥8% and/or horizontal or vertical cup/disk ratio increase ≥0.2 compared to baseline. Mixed-model ANCOVA was used to test for significant change from baseline to 5-year follow-up. Times to functional and structural progression were analyzed using Cox proportional hazards models.

Results: OA Peak Systolic Velocity (PSV) was 23.0 (95% CI; 20.9, 25.4) at baseline, 21.8 (19.4, 24.4) at 5 years, change of -1.3 (-3.5, 0.7; p= 0.21), OA End Diastolic Velocity (EDV) significantly decreased from 5.6 (5.1, 6.2) at baseline to 3.9 (3.5, 4.4) at 5 years, change of -2.4 (-3.3, -1.6; p<0.0001). CRA PSV and EDV significantly decreased with changes of -0.6 (-1.1, -0.1; p=0.0126) and -0.8 (-1.1, -0.5; p<0.0001), respectively. NPCA and TPCA EDV significantly decreased with changes of -0.7 (-0.9, -0.4; p<0.0001) and -0.7 (-1.0, -0.5; p<0.0001), respectively, while neither NPCA nor TPCA PSV changed significantly. Resistivity indices (RI) in all retrobulbar vessels significantly increased over 5-years (p<0.0001). Lower OA PSV and OA EDV were associated with shorter time to functional and structural progression (p<0.05).

Conclusions: Retrobulbar blood flow velocities decreased and resistivity indices increased over 5 years. Lower OA blood flow velocities were predictive of glaucomatous functional and structural progression after 5 years.