The agreement and correlation between manual and automated measurements of SFCT are summarized in
Table 2. Among all 2896 participants, a strong correlation was observed between the two methods, with an ICC of 0.971 (95% confidence interval [CI], 0.969–0.973;
P < 0.001) and a Pearson correlation coefficient of 0.976 (
P < 0.001) (
Fig. 2). The 95% LOA ranged from −84.77 µm to 23.91 µm, with 4.8% of measurements falling outside these limits (
Fig. 3). A significant fixed bias was observed, with manual measurements being on average 30.42 µm lower than automated measurements (95% CI, −31.43 to −29.44,
P < 0.001). A significant proportional bias was also present (B = −25.75; 95% CI, −28.60 to −22.90;
P < 0.01). When stratified by age, participants aged ≥60 years had an ICC of 0.954 (95% CI, 0.946–0.963,
P < 0.001) and a Pearson correlation coefficient of 0.974 (
P < 0.001), while those aged <60 years demonstrated an even higher ICC of 0.971 (95% CI, 0.967–0.972;
P < 0.001) and a Pearson correlation coefficient of 0.953 (
P < 0.001), indicating strong consistency between the two methods in both age groups. Significant fixed and proportional biases were observed in both groups (all
P < 0.001), with slightly greater fixed biases in the younger participants (−32.12 µm vs. −29.35 µm). When stratified by axial length, participants with axial length ≥23 mm had an ICC of 0.969 (95% CI, 0.966–0.972;
P < 0.001) and a Pearson correlation coefficient of 0.974 (
P < 0.001), whereas those with axial length <23 mm also showed strong consistency with an ICC of 0.959 (95% CI, 0.954–0.963;
P < 0.001) and a Pearson correlation coefficient of 0.963 (
P < 0.001). In both groups, significant fixed and proportional biases were detected (all
P < 0.001). The group with axial length <23 mm demonstrated a slightly larger fixed bias (−32.88 µm vs. −28.59 µm). When stratified by SFCT level, participants with SFCT ≥300 µm showed relatively lower agreement, with an ICC of 0.867 (95% CI, 0.852–0.882;
P < 0.001) and a Pearson correlation coefficient of 0.868 (
P < 0.001), although the consistency remained strong. In contrast, participants with SFCT <300 µm demonstrated stronger correlation, with an ICC of 0.942 (95% CI, 0.937–0.947;
P < 0.001) and a Pearson correlation coefficient of 0.944 (
P < 0.001), along with narrower limits of agreement (−73.91 µm to 13.11 µm) and a lower proportion of outliers (4.6%). Significant fixed and proportional biases were observed in both SFCT subgroups (all
P < 0.001).