OCT-A is better than RNFL at discriminating advanced glaucoma severity levels.

Abstract

Purpose : To study the ability of peripapillary microvascular density on OCT-A in different sectors and layers to discriminate between glaucoma severity levels.

Methods : OCT-A images (Zeiss Cirrus 5000 HD-OCT) from 39 healthy subjects and 82 glaucoma patients (one eye per patient) were analysed with an in-house algorithm. The peripapillary microvascular density of six layers (superficial and deep vascular plexus, whole retina, avascular layer, choriocapillaris, and choroid) and seven sectors (Garway-Heath sectors plus circumpapillary region) were assessed. The circumpapillary RNFL thickness was also evaluated. Glaucomatous damage was categorized based on visual field mean deviation (mild above -6 dB, n=37; moderate between -6 and -12 dB, n=26 and severe worse than -12 dB, n=19). A group comparison with the Kruskal-Wallis test followed by the Mann-Whitney U test with Holm-Bonferroni correction for pairwise comparison were performed to infer the ability of each region to discriminate glaucoma severity levels.

Results : A significant difference (p≤0.001) was observed between the healthy and glaucoma groups for the circumpapillary RNFL and for the microvascular density in all sectors and layers, except for the avascular layer. The post-hoc analysis revealed no significant differences for the circumpapillary RNFL between moderate and severe glaucoma (p=0.38). In contrast, circumpapillary microvascular density in the superficial, deep and whole retina layers presented a significant difference between all severity groups (p≤0.001), including between moderate and severe glaucoma (p<0.05).The inferotemporal sector was the best at discriminating between controls, mild and moderate glaucoma, whereas the inferonasal sector was the best between moderate and severe glaucoma.

Conclusions : Peripapillary microvascular density is able to categorize glaucoma severity levels. The most discriminant region changes with increasing disease severity, shifting from the inferotemporal to the inferonasal sector.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1 – Pairwise comparison of peripapillary microvascular density between severity groups for all layers and sectors by categorized p-values.