Foveal avascular zone area measurements in a normal Egyptian population using Heidelberg optical coherence tomography angiography and its various correlations

Abstract

Purpose The aim of this study was to measure the foveal avascular zone (FAZ) area at both superficial and deep retinal capillary plexus levels in normal emmetropic and highly myopic eyes, using the Heidelberg optical coherence tomography angiography (OCTA) and to find its correlation with central macular thickness and volume and best-corrected visual acuity.Patients and methods This is a prospective cross-sectional observational study that involved 69 normal emmetropic and highly myopic eyes of Egyptian patients. FAZ area (both at the superficial and deep capillary plexus levels), central macular thickness, and volume were measured by the Heidelberg OCTA. Best-corrected visual acuity in Illiterate E lines was also reported.Results In normal individuals, the mean value of the FAZ was 0.38±0.11 mm2 for the superficial FAZ and 0.29±0.10 mm2 for the deep FAZ, with higher statistically significant values for the superficial FAZ size (P<0.05, t test=13.64). Pearson correlation test revealed a statistically significant negative correlation (P<0.05) between central macular thickness and both the superficial FAZ size (r=−0.33) and deep FAZ size (r=−0.39) and a highly significant negative correlation (P<0.01) between central macular volume and both superficial FAZ size (r=−0.40) and deep FAZ size (r=−0.42). Best-corrected visual acuity showed an insignificant correlation (P>0.05) with both superficial and deep FAZ size. Neither high myopia nor sex influenced the results.Conclusion Using the Heidelberg OCTA in normal Egyptian individuals, the superficial FAZ size ranged from 0.19 to 0.85 mm2, which was larger than the deep FAZ, which ranged from 0.09 to 0.73 mm2. FAZ size measurements were strongly correlated with central macular thickness and volume. Neither high myopia nor sex influenced the results.