To investigate the agreement and correlation of manual central foveal thickness (CFT) measurements using the Heidelberg Eye Explorer and ImageJ software.

Optical coherence tomography (OCT) images were identified. CFT was measured using the Heidelberg Eye Explorer caliper tool. Two independent graders measured the CFT of the same images using ImageJ software. A Pearson correlation coefficient, intraclass correlation coefficient, Bland–Altman plots, and coefficient of repeatability were used to assess the agreement and correlation between the Heidelberg Eye Explorer and ImageJ measurements.

One-hundred and twenty-two OCT images from 91 patients were analyzed. Mean CFT as measured using the Heidelberg caliper tool was 264.8 ± 113 µm. Using ImageJ software, graders 1 and 2 obtained mean CFT values of 267 ± 114.3 µm and 270 ± 114.8 µm, respectively. Pearson correlation revealed a strong correlation between the Heidelberg and Image J measurements (r = 0.999, p < 0.0001). Bland–Altman plots noted a less than 4 µm mean difference between Heidelberg and ImageJ CFT values (2.67 ± 3.46 and 3.72 ± 2.78 µm for graders 1 and 2, respectively).

There was strong agreement between the Heidelberg Eye Explorer and ImageJ software for manual CFT measurements. ImageJ may be a reliable tool for thickness measurements when proprietary OCT software is unavailable