Choroidal Thickness in healthy eyes measured by Widefield Optical Coherence Tomography.

Introduction: The choroid and its role in posterior segment pathology has become an increasing subject of study. The objective of the present study was to analyze choroidal thickness (CT) in healthy eyes by widefield (WF) optical coherence tomography (OCT) up to the periphery and to compare the reliability of manual versus automatic measurement.

Methods: Cross-sectional and non-interventional study conducted on 191 healthy eyes of 101 patients. All patients were scanned by using WF-OCT (Xephilio WF-OCT S1; Canon Corp, Tokyo, Japan). CT was measured in 2000 µm intervals automatically using the built-in software and manually by two masked observers. All analyses were performed using the IBM-PSSS statistical software program (IBM-SPSS, v. 28.0.0.0, Chicago, IL, USA).

Results: CT was measured in 100% of the sample. The mean age of the study cohort was 39.05±19.06 years old. Mean subfoveal (SF)CT measured automatically was 343.67±84.18 μm and manually was 336.55±75.57 μm. The thickest point was located 2000 μm from the fovea in the superior sector in 62.83% of the subjects. According to age distribution, mean CT became significantly thinner from 40 years of age. When comparing automatic and manually measuring, the intraclass correlation coefficient was excellent (p<0.01) in all quadrants. Moreover, manual measurement interobserver agreement was excellent in all quadrants (p<0.01).

Conclusion: The automatic system is valid and serves as the basis of choroid measurement. In more than 50% of the healthy subjects, superior CT is thicker than subfoveolar CT and mean CT became significantly thinner from 40 years of age.