Inter-Individual Topographic Variation of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography.

Abstract

To investigate the topographic characters of inter-individual variations of the macular choroidal thickness (CT). This was a retrospective study. Macular CT data for 900 0.2 × 0.2-mm grids from 410 healthy eyes were collected from swept-source optical coherence tomography. Following the analysis of factors associated with mean CT, the β-coefficients of the included associated factors in each grid were summarized for choroidal thickness changes analysis. Additionally, the coefficient of variance (CoV), coefficient of determination (CoD), and coefficient of variance unexplained (CoVU) for CT were calculated in each individual grid to investigate the inter-individual choroidal variations pattern. Sex (β = -17.26, female vs. male), age (β = -1.61, per 1year), and axial length (β = -18.62, per 1mm) were associated with mean macular CT. Females had a thinner choroid in all 900 grids (0.5-26.9µm). As age increased, the CT noticeably decreased (8.74-19.87µm per 10years) in the temporal regions. With axial length elongation, the thinning (7.94-24.91µm per 1mm) was more evident in subfoveal and nasal regions. Both the CoV (34.69%-58.00%) and CoVU (23.05%-40.78%) were lower in the temporal regions, whereas the CoD (18.41%-39.66%) was higher in the temporal regions. Choroidal thinning is more predominant in the subfoveal and nasal regions with axial length elongation, but in the temporal region with aging. The inter-individual variation of CT is higher and less determined by sex, age, or axial length in the nasal regions. Topographic variation should be considered when interpreting choroidal thickness.