Bridging the Gap: Innovations in Choroidal Thickness Measurement by a Semi-automated Method.

Objective Changes in choroidal thickness (CT) are considered a potential biomarker for myopia progression. Numerous studies have shown that CT decreases as axial length increases. It is hypothesized that the thinning of the choroid in myopic eyes may be due to mechanical stretching of the sclera as the eye elongates, leading to a reduction in choroidal blood flow and tissue volume (1,2). The manual method in the built-in OCT software is usually used to measure the CT (3,4). This method can be time consuming, Operator biased, and only sub-fovea areas or vicinities are usually measured. In this study a semi-automated method using ImageJ technique is introduced for assessing CT before and after a near task of 10 minutes. Methods CT was measured in 28 subjects using both a manual method and a semi-automated ImageJ-based method. Measurements were taken before and after a near task to assess agreement and potential changes in CT. Paired t-tests, Bland-Altman analysis, and Pearson correlation were calculated. Results The ImageJ method showed strong agreement with the manual technique, with correlation coefficient of 0.96 pre-task and 0.97 post-task (p < 0.001). Mean differences between the methods were -1.6 ± 12.8 µm pre-task (p = 0.50) and 4.4 ± 13.0 µm post-task (p = 0.08). Bland-Altman analysis demonstrated narrow limits of agreement indicating consistency between the two methods. Coefficients of variation was (0.07 for the manual, 0.06 for the ImageJ) which shows comparable repeatability. No significant differences in CT were observed pre- and post-task using either method (p > 0.05). Conclusions The semi-automated ImageJ method provides a reliable and repeatable alternative to manual measurement for assessing CT offering wider range of lines across the center and peripheral choroid. Both methods showed good agreement, supporting the possibility of ImageJ use for future studies examining CT changes.