Capillary Density Measured by OCT Angiography in Glaucomatous Optic Disc Phenotypes

Abstract

Purpose : To compare optical coherence tomography angiography (OCTA) measured capillary density of the optic disc among four glaucomatous phenotypes.

Methods : 92 eyes of 55 healthy subjects and 193 eyes of 141 glaucoma patients from the Diagnostic Innovations in Glaucoma Study (DIGS) with good quality OCTA optic disc images were included in this cross-sectional study. Global and sectoral circumpapillary capillary density (cpCD) in four glaucomatous phenotypes were compared using mixed model. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy among groups after adjusting for age, visual field mean deviation (VF MD), and scan quality (SQ).

Results : Four glaucoma phenotypes were assessed: focal ischemic (n=45), generalized cup enlargement (n=60), myopic glaucomatous (n=38), and senile sclerotic (n=50). Sex, race, age, mean ocular perfusion pressure, intraocular pressure, and VF MD did not differ among phenotypes. However, there was a significant difference in axial length (P=0.033), and retinal nerve fiber layer thickness (RNFLT) (P<0.001) among the groups. After adjusting for confounders, senile sclerotic discs had the lowest mean [95% CI] cpCD (37.1 % [35.3 – 38.8]) followed by focal ischemic (41.8 % [40 – 43.6]), myopic glaucoma disc (42.1 % [40 – 44.2]), and discs with generalized cup enlargement (45.5 % [44 – 47]). (p<0.001). Similar results were found after adjustment for RNFLT. The adjusted AUROC curves of cpCD for discriminating between healthy and glaucomatous eyes were highest in senile sclerotic eyes (0.928) and lowest in generalized cup enlargement eyes (0.704).

Conclusions : Optical coherence tomography angiography capillary density parameters differed among glaucoma optic disc phenotypes and were lowest in the senile sclerotic glaucomatous optic disc phenotype. Longitudinal studies are needed to establish the relationship between capillary density and the pathophysiology of glaucoma.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1: Glaucomatous optic disc types classified into four groups as described by Nicolela and Drance.

 

Figure 2: The estimated percentage loss of capillary density in four distinct optic disc phenotypes.