The Relationship Between Ocular Blood Flow and Structural Changes in Glaucoma Patients: The Indianapolis Glaucoma Progression Study

Abstract

Purpose: : To investigate the relationship between retrobulbar blood flow velocities, vascular resistivity and optic nerve head structural changes observed in primary open angle glaucoma (POAG) patients.

Methods: : Color Doppler imaging (CDI) was performed on 61 subjects with POAG (mean age: 65.7 2.6 SD; 51% female) participating in the Indianapolis Glaucoma Progression Study (IGPS). Peak systolic (PSV) and end diastolic (EDV) flow velocities were measured in the ophthalmic (OA), central retinal (CRA), and nasal and temporal short posterior ciliary arteries (N/TPCA). Pourcelot’s resistivity index was calculated. Retinal nerve fiber layer (RNFL) thickness was measured by optical coherence tomography (OCT) (Stratus 4, Zeiss). The strength of the linear association was measured by calculating Pearson Correlation Coefficients and p values <0.05 were considered significant.

Results: : The RNFL thickness in the inferior, superior, nasal, and temporal regions was 90.9 µm SD 29.9, 87.7 µm SD 24.8, 64.1 µm SD 22.5, 56.4 µm SD 14.8, consistent with the "ISNT" rule which describes the common pattern of NFL thickness. The mean thickness of the RNFL was 74.7 µm SD 17.6. An increase in the PSV and EDV of the CRA positively correlated with the thickness of the RNFL in the superior region (r=0.28 p=0.02; r=0.30 p=0.02), as well as the mean thickness (r=0.30 p=0.01; r=0.32 p=0.01). The RNFL thickness in the temporal region positively correlated with the EDV of the CRA (r=0.26 p=0.03). No correlation was found between the thickness of the RNFL and the blood velocities of the OA or PCAs.

Conclusions: : Central retinal artery blood flow, which supplies the retinal ganglion cells and the inner nerve fiber layer, was positively correlated with the mean thickness of the nerve fiber layer as measured by the Stratus OCT in POAG patients.

Keywords: retina • imaging/image analysis: clinical • blood supply