AUG 12, 2020
This study assessed the relationship between retinal vessel density on OCT angiography and visual field sensitivity loss in highly myopic eyes with primary open-angle glaucoma (POAG).
Researchers used OCT angiography to assess the peripapillary retinal vessel density, spectral-domain OCT to assess circumpapillary retinal nerve fiber layer (RNFL) thickness and standard automated perimetry to assess visual field sensitivity loss. Topographical correlations between visual field sensitivity loss and either vessel density or RNFL thickness were determined in subgroups divided according to the presence of a segmentation error.
Of the 124 myopic POAG eyes enrolled, 40 showed a segmentation error in OCT scans while 84 did not have an error. The peripapillary retinal vessel density significantly correlated with visual field sensitivity loss in the highly myopic eyes with or without a segmentation error. The vessel density measured using OCT angiography revealed an association with visual field sensitivity loss even when it was difficult to detect glaucomatous damage using OCT because of a segmentation error.
The study initially enrolled 231 eyes but had to exclude 46% due to poor quality of OCT or OCT angiography images. The measured vessel density may have included parapapillary atrophy (PPA) because the retinal vessel density was evaluated using the same circular area but did not consider tilted disc size. This may have led to imprecise vessel density measurements because the vessel density of a tilted disc with a large area of PPA is likely to be lower. Because of the cross-sectional study design, the study was not able to evaluate the possible confounding effects of systemic conditions such as blood pressure or systemic medications on vessel density.
These findings suggest OCT angiography could be a useful adjunct in evaluating glaucomatous visual field damage in highly myopic eyes, especially when the RNFL thickness measured using OCT is not reliable due to a segmentation error.