Abstract
Purpose :
The macular and peripapillary vessel density measured using optical coherence tomography angiography (OCTA) is important in monitoring advanced glaucoma patients due to the lower measurement floor than the thicknesses of retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC). However, whether the repeatability of OCTA parameters changed with disease severity was not investigated. We aimed to investigate the repeatability of OCTA parameters in patients with different severity of glaucoma.
Methods :
Patients with primary open-angle glaucoma were prospectively enrolled and divided into mild (mean deviation [MD] of 24-2 visual field VF] test ≥ -6 dB), moderate-to-advanced (-6 > MD ≥ -20 dB), and severe glaucoma group (MD < −20 dB). RTVue (Optovue Inc) OCTA was performed three times within a single visit to obtain superficial and deep macular VD, and peripapillary VD. The intrasession variability of these parameters was assessed by the coefficient of variation (CoV) and intraclass correlation coefficient. Their association with glaucoma severity, assessed by MD and the thickness of RNFL and GCC, was analyzed.
Results :
We enrolled 57, 92, and 39 eyes in the mild, moderate-to-advanced, severe glaucoma groups, respectively. The overall repeatability coefficients (%) for superficial macular VD, deep macular VD, and peripapillary VD were 4.0, 6.1, and 4.5, respectively. CoV (%) for superficial (3.1±1.9, 4.1±3.2, 6.3±4.6, P < 0.001) and deep macular VD (3.5±2.1, 5.0±3.7, 6.4±4.5, P < 0.001), and peripapillary VD (2.9±2.2, 4.2±3.6, 4.9±3.3, P = 0.004) increased with glaucoma severity. In the multivariable regression, greater CoV of superficial and deep macular VD, and peripapillary VD were associated with worse MD (superficial macular VD, P = 0.042; deep macular VD, P = 0.012; peripapillary VD, P = 0.017) and scan quality index (SQI) (All P < 0.001) rather than the thicknesses of RNFL and GCC. The association between CoV values of superficial and deep macular VD and MD was exclusively noticed in patients with suboptimal image quality (SQI < 7). The relationship between CoV of peripapillary VD and MD did not vary with SQI.
Conclusions :
The intrasession variability of OCTA parameters increased with more severe VF defects, especially in those with suboptimal scan quality. Greater variability should be considered when interpreting the results of OCTA in advanced glaucoma patients.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.