Fractal Dimension Analysis of Peripapillary Microvasculature in Primary Congenital Glaucoma.

Abstract

Precis: In this prospective multicenter study, eyes with primary congenital glaucoma exhibited lower retinal vascular parameters compared to healthy controls, as assessed by optical coherence tomography angiography fractal dimension analysis.

Purpose: To study the retino-choroidal peripapillary microvascular pattern in primary congenital glaucoma (PCG) using fractal dimension (FD) analysis and compare it to healthy controls.

Methods: This was a prospective multicenter comparative study. We obtained peripapillary optical coherence tomography angiography (OCTA) scans (Optovue Inc, Fremont, CA) and computed FD at the vitreous/retina (large retinal vessels), inner limiting membrane/nerve fiber layer (ILM-NFL) (radial peripapillary capillary plexus, RPC), and the choroid. Other peripapillary OCTA parameters, including the whole image inside the disk and peripapillary superior and inferior vascular density (VD) parameters, were also collected. One eye per patient was included in the analysis.

Results: We included a total of 17 PCG eyes and 24 control eyes. The mean age at the time of enrollment was 8.24±0.75 years in the PCG group compared to 8.33±1.09 in controls (P=0.74). Eight patients (47%) in the PCG group and 14 (58.3%) in the control group were male. Among the PCG group, the mean vitreo-retina (large retinal vessels) FD (1.79) and ILM-NFL (RPC) FD (1.75) were significantly reduced compared to controls (vitreo-retina FD (1.85), ILM-NFL FD (1.82), P-value 0.011 and 0.014, respectively). There was no statistically significant difference in the averaged choroidal FD between both groups (1.89 vs. 1.88, P=0.29). All optic nerve VD parameters (whole image, inside disc, superior, and inferior-hemi) were also significantly reduced in the PCG group.

Conclusion: PCG was associated with lower vascular parameters in the vitreo-retina (large retinal vessels) and ILM-NFL (RPC) layers as detected by OCTA FD.