Unmeasurable small size of foveal avascular zone without visual impairment in optical coherence tomography angiography

Abstract

Purpose: To report the clinical characteristics of eyes with an unmeasurable small size of foveal avascular zone (FAZ) in the optical coherence tomography angiographic (OCTA) images. Methods: Two-hundred sixty-seven eyes of 255 patients (mean age 60.4 years) without retinal and choroidal disorders to cause any type of visual impairment were examined by optical coherence tomography angiography (OCTA; RTVue XR Avanti, Optovue, Fremont, CA). Cross-sectional images at the fovea (DRI-OCT, Topcon, Japan) and fundus autofluorescence (CX-1 MYD/NM, Canon, Japan) were also recorded from all eyes. Results: Four eyes (1.5%) of 3 patients (2 men, 1 woman; average age, 63.3 years) were found to have an unmeasurable small size of FAZ in the OCTA images. The best-corrected visual acuity was better than 20/20 in all eyes. Cross-sectional OCT images showed the presence of a foveal depression and the inner retinal layers in the foveal depression. These inner retinal layers were detected as a hyperreflective bands at the fovea. Fundus autofluorescence showed hypo-autofluorescence at the fovea as in normal eyes. Conclusions: An unmeasurable small size of FAZ without visual impairment was detected in 1.5% of 267 normal eyes. These eyes may be classified as low-grade foveal hypoplasia.