Evaluating the distribution of laterally corrected foveal avascular zone parameters.

Abstract

Purpose : To examine the distribution and interocular symmetry of foveal avascular zone (FAZ) parameters after correction for lateral magnification, in a large cohort of healthy, young adults.

Methods : Participants underwent a comprehensive ophthalmic examination including axial length measurement and optical coherence tomography angiography (OCTA) imaging of the macula. OCTA images of combined superficial and deep retinal vessel plexuses were processed via a custom software to extract foveal avascular zone area (FAZA) and vessel density in a 300-µm annulus surrounding the foveal avascular zone (FD-300), with and without correction for lateral magnification. Bland-Altman analyses were performed to examine the effect of lateral magnification on FAZA and FD-300, as well as to evaluate the interocular agreement in both parameters.

Results : OCTA images were acquired in 504 adults (261 females [51.8%], 243 males [48.2%]; average [standard deviation] age: 28.2 [0.7]). The mean (SD) of laterally corrected FAZA and FD-300 were 0.22 (0.10) mm² and 51.9 (3.2) %, respectively. Relative to raw, uncorrected data, 55.6% of corrected FAZA showed a relative change greater than 5% while all FD-300 changes were within 5%. There was good interocular symmetry (mean OD-OS difference, 95% limits of agreement) in both FAZA (0.006, -0.077 to 0.118 mm²) and FD-300 (-0.05, -5.39 to 5.30 %).

Conclusions : Clinicians should strongly consider accounting for lateral magnification when evaluating FAZA. If working with a 5% error margin, correcting for lateral magnification is not necessary when evaluating FD-300. Good interocular agreement in FAZA and FD-300 suggests the contralateral eye can be used as control data.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.