Patterns of Peripapillary Retinal Nerve Fiber Layer Thickness and Capillary Density Loss in Primary Open Angle Glaucoma

Abstract

Purpose : To characterize global and regional rate of change of retinal nerve fiber layer thickness (RNFL) thickness and circumpapillary capillary density (cpCD) in primary open angle glaucoma (POAG) eyes in different stages of glaucoma.

Methods : 94 eyes (22 glaucoma suspect and 72 POAG) from 67 patients who underwent optical coherence tomography angiography (OCTA) imaging and spectral domain OCT imaging for capillary density and RNFL measurements, respectively, on 3 or more different dates were included from the Diagnostic Innovations in Glaucoma Study. The rates of capillary density loss and RNFL thinning were calculated globally and sectorally in each glaucoma stage and compared using mixed effects models.

Results : The mean follow-up time and number of visits were 2.8 years and 4.1 visits. Significant rates of capillary loss and RNFL thinning were detected globally in glaucoma suspect and POAG eyes (all P<0.05 comparing with 0 slope). In glaucoma suspect eyes, both rate of capillary density loss and RNFL thinning was fastest in inferotemporal and supratemporal sectors. In POAG eyes, the rate of capillary density loss was fastest in supratemporal and inferotemporal sectors, and RNFL thinning was fastest in inferonasal and infratemporal sectors. Significant mean capillary loss was found globally and in some sectors in eyes with moderate to advance glaucoma. However, no RNFL thinning was detected in any sectors in these eyes. While the rates of capillary density loss and thickness loss were correlated [with strongest association in inferotemporal sector (R²=51.2%,p=0.003)] in glaucoma suspects, no correlation (p>0.05 for all) was found between the rates of capillary density loss and thickness loss globally and sectorally in POAG. In POAG, faster mean rates of cpCD loss was significantly associated with worse baseline visual field mean deviation (VF MD) (-0.04 %/year per 1 dB VF MD 95%CI(-0.08, -0.01),p=0.042). However, rate of RNFL thinning slowed with worse baseline VF MD (0.08 µ/year per 1 dB VF MD (0.05, 0.12),p<0.001).

Conclusions : While progressive vessel density and RNFL thickness loss were detectable globally and sectorally in this cohort, capillary density and thickness loss were correlated only in glaucoma suspects. In POAG eyes, with worsening of the disease, the rate of capillary loss became faster and the rate of RNFL loss became slower.

This is a 2020 ARVO Annual Meeting abstract.