Hemiretinal vessel density asymmetry supplements diagnostic accuracy of retinal nerve fiber layer thickness for glaucoma

Abstract

Purpose : This study investigates hemiretinal asymmetry in radial peripapillary capillary vessel area density (VAD) of healthy, glaucoma suspect, and primary open angle glaucoma (POAG) eyes of varying severity, and its diagnostic utility, alone and in combination with other ocular parameters, for POAG.

Methods : 6x6-mm optic disc scans were collected on optical coherence tomography angiography to obtain VAD and on OCT to measure circumpapillary retinal nerve fiber layer (RNFL) thickness. Hemiretinal difference in VAD (hdVAD) was defined as the absolute difference between superior and inferior hemiretinal VAD. Age-adjusted multivariable linear regression of hdVAD on POAG severity was performed. Area under curves (AUCs) were calculated from predicted probabilities generated by multiple logistic regression of POAG severity on age-adjusted values of either a single parameter or a combination of parameters. DeLong’s test was used to determine the statistical significance of differences in AUCs from various models, thus identifying parameters with the greatest diagnostic accuracy.

Results : 1069 eyes of 1069 participants (602 healthy, 275 glaucoma suspect, and 192 POAG classified into 70 mild, 56 moderate, and 66 severe POAG) were included. After adjusting for age, mean hdVAD was similar between healthy and suspect (β = 0.002, P = 0.253), higher in mild versus suspect (β = 0.013, P < 0.001), higher in moderate versus mild (β = 0.010, P = 0.009), but lower in severe versus moderate (β = -0.012, P = 0.001). AUCs of hdVAD were qualitatively highest for mild (0.674) and moderate (0.685) POAG (versus 0.515 for suspect, 0.602 for severe POAG, 0.655 for any POAG). A combination of hdVAD and global RNFL (gRNFL) had the highest AUC of all parameters for mild (0.809) and any POAG (0.851), which were greater than AUCs of either hdVAD (P < 0.001 for both comparisons) or gRNFL (P = 0.041 for mild, P = 0.048 for any POAG) alone.

Conclusions : hdVAD is higher in early POAG and may help with early detection when damage is focal, but its diagnostic ability appears to be less robust in advanced POAG when damage is diffuse. Combination of hdVAD and gRNFL yielded the best diagnostic accuracy of all parameter permutations for mild and any POAG, suggesting the potential of hdVAD to supplement gRNFL and other ocular parameters in the diagnosis of early POAG.

This is a 2021 ARVO Annual Meeting abstract.