Repeatability of vessel density measurements using optical coherence tomography angiography in retinal diseases

To analyse the repeatability of vessel density (VD) measurements using optical coherence tomography angiography (OCTA) in patients with retinal diseases.

Two consecutive VD measurements using OCTA were analysed prospectively in patients with retinal diseases (diabetic macular oedema (DME), retinal vein occlusion (RVO) with macular oedema, epiretinal membrane (ERM), wet age-related macular degeneration (AMD)). The intraclass correlation coefficient (ICC), coefficient of variation (CV) and test-retest SD of VD measurements were assessed, and linear regression analyses were conducted to identify factors related to repeatability.

A total of 134 eyes were analysed involving 20 eyes with DME, 44 eyes with RVO with macular oedema, 50 eyes with ERM and 20 eyes with wet AMD. The mean age was 64.9 years, and the mean best-corrected visual acuity (BCVA) was 0.24. The mean central macular thickness (CMT) was 391.6 µm, and the mean ganglion cell-inner plexiform layer (GC-IPL) thickness was 61.4 µm. In all four diseases, the ICC and CV of the full VD were 0.812 and 6.72%, respectively. Univariate analyses showed that the BCVA (B, 8.553; p=0.031), signal strength (B, -1.688; p=0.050), CMT (B, 0.019; p=0.015) and mean GC-IPL thickness (B, -0.103; p=0.001) were significant factors that affected the repeatability. Multivariate analyses of these factors showed a significant result for the GC-IPL thickness.

Measurements of the VD using OCTA showed relatively good repeatability for various retinal diseases. The BCVA, signal strength, CMT and GC-IPL thickness affected the repeatability, so these factors should be considered when analysing the VD.