Interchangeability and reliability of macular perfusion parameter measurements using optical coherence tomography angiography

Aim The aim of the study was to investigate the interchangeability and reliability of macular perfusion measurements using optical coherence tomography angiography. Methods A prospective cross-sectional observational study. Healthy adult Chinese subjects were recruited. Macular perfusion parameters were automatically analysed by software included in a spectral-domain optical coherence tomography system. The vessel density (VD) of the whole, parafovea, superior-hemi, inferiorhemi, fovea, temporal, superior, nasal and inferior quadrants as well as the foveal avascular zone (FAZ) and choroidal capillary VD (CCVD) were quantified. Results A total of 51 eyes in 27 subjects were included (8 men and 19 women, mean age 24 +/- 4 years). Significant differences in VD of all quadrants (all p<0.001) was detected between the 3x3 mm and 6x6 mm macular scan size. The biggest difference of VD between the two scan size was 5.14 +/- 4.03, which was not clinically meaningful. No statistically significant differences were found in FAZ or CCVD between the two different scan sizes. The mean intraclass correlation coefficient (ICC) between two measurements from the inter-rater of 20 eyes was from 0.560 to 0.893 for VD and 0.845 for FAZ. The mean ICC between two measurements from the intrarater of 20 eyes was from 0.497 to 0.870 for VD and 0.780 for FAZ. Conclusions FAZ and CCVD are interchangeable between the 3x3 mm and 6x6 mm macular scan sizes. The VD differences between the two different scan sizes are not clinically meaningful. The macular perfusion parameters presented good but not perfect reliability, which should be acknowledged in clinical practice.