Microvasculature changes in macular region in glaucomatous eyes using optical coherence tomography-based angiography (OCTA)

Abstract

Purpose : To investigate the changes in macular vascular microcirculation in glaucomatous eyes and its correlation with glaucoma severity using OCTA.

Methods : Eyes diagnosed with open angle glaucoma and normal disc were scanned centered at the foveola using a swept-source OCTA (Plex Elite 9000, Zeiss, Dublin, CA) covering a 6mm x 6mm area with 500 x 500 sampling points. Glaucomatous eyes were divided into three groups based on the progression of their optic nerve damage as measured by visual field (VF) mean deviation (MD): mild (MD>-6.0 dB), moderate (-12.0 dB≤MD≤-6.0 dB), and severe (MD<-12.0 dB). Blood flow signals were extracted using a complex optical microangiography (OMAG) method and exported from the Plex Elite device. Ganglion cell and inner plexiform layer (GCIPL) was segmented using proprietary semi-automatic segmentation software. Macular vascular en face images were generated using blood flow signals by detecting the highest flow intensity along the axial direction within the GCIPL. Macular vascular microcirculation was then measured by calculating the overall blood flux index (the mean flow signal intensity) and vessel area density (percentage of the detected vessels) over the entire 6mm x 6mm area excluding the big retinal vessels and compared among groups. The Kruskal-Wallis tests were used to analyze the significance of differences among the four groups. Univariate linear regression models were used to analyze the correlation between macular microcirculation and disease severity.

Results : Thirteen eyes from 13 normal and 42 eyes (24 mild, 9 moderate, and 9 severe) from 32 glaucoma subjects were recruited. There was no significant difference in age among groups (p=0.78), while significant differences in VF MD and GCIPL thickness were found (p≤0.0183) except the GCIPL thickness between moderate and severe in glaucoma group. The blood flux index and vessel area density were significantly lower in glaucomatous eyes compared with normal eyes and among groups (p≤0.0002, Table) and were significantly correlated with the severity of glaucoma (R²≥0.25, p≤0.0008, Figure).

Conclusions : Macular vascular microcirculation detected by OMAG showed significant differences among normal and glaucomatous eyes and showed strong correlation with glaucoma severity. Macular vascular microcirculation measurements using OMAG may be important for the monitoring of glaucoma progression.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.