Longitudinal OCTA vessel density loss in macula and optic nerve head in healthy, glaucoma suspect and established glaucoma eyes.

Objective: To examine longitudinal optical coherence tomography angiography (OCTA) changes in macula and optic nerve head (ONH) in healthy, glaucoma suspect (GS) and primary open-angle glaucoma (POAG) eyes.

Methods: Healthy, GS and POAG eyes from Diagnostic Innovations in Glaucoma Study with ≥2 years follow-up and four visits of macular/ONH OCTA imaging were included. Rates of macular wiVD (whole-image vessel density) and ONH wiCD (whole-image capillary density) changes were calculated for each diagnosis group using join mixed-effect modelling. Differences in wiVD/wiCD change rates across diagnoses were examined through pairwise comparison. Relationships of baseline 24-2 visual field (VF) mean deviation (MD) with wiVD/wiCD change rates were evaluated for POAG eyes.

Results: There were 36, 57 and 79 eyes (25, 38 and 50 subjects) in healthy, GS and POAG groups, respectively. Rates of wiVD (range:-0.72 to -0.92 %/year) and wiCD (range:-0.28 to -0.66 %/year) loss were different from zero in all groups (p<0.05). The rates of wiCD loss differed across all diagnosis groups (p<0.001), while wiVD change rates did not increase when comparing healthy to GS eyes (p=0.167). Baseline VF MD showed a significant but modest correlation with the rates of both wiVD and wiCD loss (p<0.05), and the correlation with wiCD change rate was slightly stronger (R2=0.27 vs 0.16).

Conclusions: In glaucoma, there is earlier microvasculature loss in the ONH than in the macula. Moreover, ONH VD loss shows a slightly stronger association with baseline VF than macular VD. Observing ONH VD loss with OCTA may help to monitor early glaucoma, which should be confirmed by future larger studies.