Evaluation of the long-term variability of macular OCT/OCTA and visual field parameters

Background/aims To assess the long-term variability of macular optical coherence tomography (OCT)/OCT angiography (OCTA) and visual field (VF) parameters.Methods Healthy and glaucoma eyes with >= 1-year follow-up were included. 24-2 VF and macular OCT/OCTA parameters, including VF mean deviation (MD), whole-image vessel density (wiVD) and ganglion cell complex thickness (wiGCC) were analysed. Intraclass correlation coefficient (ICC), root mean squared error (RMSE), within-subject test-retest SD (Sw) and test-retest variability were calculated for stable eye cohort (max follow-up=1.5 years). Rates of change and RMSE were evaluated in the extended cohort including all eyes (unlimited follow-up).Results From a total of 230 eyes (150 participants; age=67.7 years), 86 eyes (37%, 62 participants) were stable. In stable eyes, OCT parameters showed the highest mean (95%) ICC (wiGCC=0.99 (0.99, 0.99)), followed by VF (VF MD=0.91 (0.88, 0.93)) and OCTA (wiVD=0.82 (0.75, 0.87)). RMSE and Sw for VF MD were 0.92 dB and 0.81 dB, respectively, for wiVD were 1.64% and 1.48%, respectively, and for wiGCC, 0.91 mu m and 0.78 mu m, respectively. The long-term test-rest variability of VF MD, wiVD and wiGCC was 2.2 dB, 4.1% and 2.2 mu m, respectively. In the extended cohort (mean follow-up=3.0 years), all parameters had significant rates of change (p < 0.001), and compared with the stable cohort, only slightly higher RMSE (VF MD=1.07 dB; wiGCC=2.03 mu m; wiVD=2.57%) were found.Conclusions VF and macular OCT/OCTA, particularly OCT parameters, showed small long-term variability in all eyes, including stable ones, supporting the use of these instruments in glaucoma follow-up. Changes in macular VD and GCC greater than 4%-5% and 2 mu m, respectively, indicate possible progression.