Interocular symmetry of the foveal avascular zone area in healthy eyes: a swept-source optical coherence tomography angiography study.

PURPOSE

To determine the presence or absence of interocular differences in the foveal avascular zone (FAZ) area in healthy eyes.

STUDY DESIGN

Cross-sectional study.

METHODS

We examined 236 healthy eyes of 118 consecutive subjects (mean age, 39.1 ± 18.9 years). We used swept-source optical coherence tomography angiography (OCTA) images of the FAZ to measure its area from both the superficial capillary plexus (SCP-FAZ) and the whole retinal capillary plexus (WCP-FAZ). We also investigated the relationship between interocular differences in SCP-FAZ and other factors such as: axial length, spherical equivalent, central retinal thickness, and retinal vascular density.

RESULTS

There was no significant difference in the FAZ area between the right and left eyes in either the SCP-FAZ (P = 0.61) or WCP-FAZ (P = 0.80), and the FAZ areas of both eyes showed significant positive correlations (SCP-FAZ; P < 0.001, R = 0.884, WCP-FAZ; P < 0.001, R = 0.856). Bland-Altman plots showed that the mean interocular difference in SCP-FAZ area was 0.002 ± 0.037 mm (95% confidence interval, -0.072-0.075 mm), and in the WCP-FAZ area, 0.050 ± 0.044 mm (95% confidence interval, -0.036-0.137 mm). Multivariate regression analysis showed that none of the investigated factors were significantly associated with interocular differences in SCP-FAZ (P = 0.61, R = 0.138).

CONCLUSIONS

There was no significant interocular difference in SCP- and WCP-FAZ areas in healthy eyes. The normal range of values for interocular difference in SCP-FAZ area was 0.002 ± 0.037 mm and in the WCP-FAZ area, 0.050 ± 0.044 mm.