PRECIS: The vessel density (VD) and perfusion density (PD) generated by optical microangiography (OMAG) is significantly affected by the signal strength (SS). Sex, hypertension, diabetes, and axial length did not have any statistically significant effect on these measurements. PURPOSE: The aim was to assess the effect of subject-related factors (age, sex, systemic hypertension, diabetes, and axial length) and machine-related factor (SS) on VD and PD generated by OMAG in peripapillary and macular regions. METHODS: In an observational, cross-sectional study of 200 eyes of 100 healthy individuals (age: 18 to 80 y), mean and sectoral VD and PD were calculated on disc and macular scans. Effect of subject-related and machine-related factors on VD and PD parameters were evaluated using multivariate mixed effect models. RESULTS: Mean±SD peripapillary and macular VD of the study population was 18.56±1.11 and 20.59±1.85 mm-1, respectively. Mean peripapillary and macular PD was 46.43±3.22% and 37.61±3.26%, respectively. Sex, hypertension, diabetes, and axial length did not have any statistically significant effect on the OMAG measurements (P>0.05 for all associations). However, the SS had significant effect on the OMAG measurements. Mean peripapillary and macular VD on scans with SS of 10 was 1.4 and 3.79 mm-1 greater, respectively, than that on scans with SS of 7. Mean peripapillary and macular PD on scans with SS of 10 was 4.43% and 7.85% greater, respectively, than that on scans with SS of 7. CONCLUSION: Significant association exists between SS of the scan and the optical coherence tomography angiography measurements generated by OMAG even when the scans have acceptable SS as recommended by the manufacturer (≥7). This needs to be considered while interpreting optical coherence tomography angiography measurements.
PRECIS: The vessel density (VD) and perfusion density (PD) generated by optical microangiography (OMAG) is significantly affected by the signal strength (SS). Sex, hypertension, diabetes, and axial length did not have any statistically significant effect on these measurements. PURPOSE: The aim was to assess the effect of subject-related factors (age, sex, systemic hypertension, diabetes, and axial length) and machine-related factor (SS) on VD and PD generated by OMAG in peripapillary and macular regions. METHODS: In an observational, cross-sectional study of 200 eyes of 100 healthy individuals (age: 18 to 80 y), mean and sectoral VD and PD were calculated on disc and macular scans. Effect of subject-related and machine-related factors on VD and PD parameters were evaluated using multivariate mixed effect models. RESULTS: Mean±SD peripapillary and macular VD of the study population was 18.56±1.11 and 20.59±1.85 mm-1, respectively. Mean peripapillary and macular PD was 46.43±3.22% and 37.61±3.26%, respectively. Sex, hypertension, diabetes, and axial length did not have any statistically significant effect on the OMAG measurements (P>0.05 for all associations). However, the SS had significant effect on the OMAG measurements. Mean peripapillary and macular VD on scans with SS of 10 was 1.4 and 3.79 mm-1 greater, respectively, than that on scans with SS of 7. Mean peripapillary and macular PD on scans with SS of 10 was 4.43% and 7.85% greater, respectively, than that on scans with SS of 7. CONCLUSION: Significant association exists between SS of the scan and the optical coherence tomography angiography measurements generated by OMAG even when the scans have acceptable SS as recommended by the manufacturer (≥7). This needs to be considered while interpreting optical coherence tomography angiography measurements.