Measurement of macular capillary network in glaucoma: An optical coherence tomography angiography (OCT-A) study

Abstract

Purpose : Retinal vascular abnormalities have been implicated in glaucoma although less is known about its association with retinal ganglion cell degeneration. This study compared (1) the diagnostic performance between vessel density (VD) of the superficial capillary plexus and ganglion cell inner plexiform layer (GCIPL) thickness measured at the macula for detection of glaucoma and (2) their association with visual function.

Methods : OCT-A (Triton OCT) of the macula, OCT macular imaging (Cirrus HD-OCT) and standard automated perimetry were performed in 147 eyes from 96 glaucoma patients, 26 pre-perimetric glaucoma subjects, and 25 healthy participants. VD of the superficial capillary plexus and GCIPL thickness were measured (Fig.1). The diagnostic performance for detection of glaucoma was determined by the area under receiver operating characteristic curve (AUC). The structure function association was evaluated with linear regression analysis. Bootstrap resampling was performed to compare the strength of association between visual sensitivity and GCIPL thickness/VD at the macula (3x3mm²).

Results : VD was smaller in glaucomatous eyes compared with healthy eyes (p<0.001) although there were no significant differences in VD between eyes with pre-perimetric glaucoma and healthy (p=0.498) or glaucoma (p=0.071) (Fig. 1). This is in contrast to GCIPL thickness in which significant differences were detected not only between the glaucomatous and normal eyes but also between eyes with pre-perimetric glaucoma and healthy or glaucomatous eyes (p≤0.001). The AUC (±SD) for discriminating glaucomatous/pre-perimetric glaucomatous eyes from healthy eyes was highest for GCIPL thickness (0.96±0.03/0.74±0.16), followed by VD (0.66±0.08/0.50±0.14). The strength of association between GCIPL thickness and visual sensitivity (R²=0.51) was stronger than that between VD and visual sensitivity (R²=0.20) (p<0.001).

Conclusions : Macular GCIPL thickness had a higher diagnostic performance for discrimination between normal eyes and eyes with glaucoma/pre-perimetric glaucoma and demonstrated a stronger association with visual function compared with VD measurement at the corresponding location. Our finding suggests that loss in the superficial macular capillary network in glaucoma is likely to be consequential to retinal ganglion cell loss.

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

 

VD maps (%, upper panel) and GCIPL thickness maps (µm, lower panel).