Abstract
Purpose :
Quantitative optical coherence tomography angiography (OCTA) measurements evaluate parafoveal vesseldensity, foveal avascular zone and macular perfusion. Reproducible measurements of these variables using 3x3mm and 6x6mm scanning protocols provide central, inner and full values (3x3 mm) and central, inner, outer and full values (6x6 mm). We conducted a non-experimental, comparative, prospective, observational, cross-sectional study to compare the determination coefficients (R2) between vessel and perfusion variables using two different OCTA protocols, to determine if their measurements are directly interchangeable.
Methods :
78 eyes from 56 healthy subjects between the ages of 18 and 30 years, with best corrected visual acuity of 0.0 in logMAR were included for the analysis. Structural optical coherence tomography and OCTA using Cirrus HD Angioplex (Carl Zeiss Meditec, Dublin CA) were performed in both eyes, as per the 3x3mm and 6x6mm scanning protocols. Distribution of the variables was determined using the Kolmogorov-Smirnov test. Values of central vessel density, central perfusion density, and foveal avascular zone area from both protocols were compared using Wilcoxon's t-test. Correlations between the corresponding variables of both protocols were calculated using Spearman's test. A linear model was used to calculate R2 for correlations >0.9 and <-0.8. Values of p <0.05 and R2 >0.9 were considered significant.
Results :
The highest R2 values were found between the central vessel and perfusion densities in both protocols individually (3x3 mm R2=0.96, 6x6 mm R2=0.98). Significant R2 values were also obtained between the inner and full densities of the 3x3 mm protocol (0.96) and the outer and full densities of the 6x6 mm protocol (0.96). The R2 value obtained from central vessel and perfusion densities between the different protocols was ≤0.71.
Conclusions :
Vessel and perfusion densities show high R2 values within the same scanning protocol, but not between different protocols, given that they preferentially measure different macular areas, thus limiting the interchangeability of the measurements.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.