Association Between Lens Thickness and SRK/T Refractive Prediction Error After Cataract Surgery: A Single-Center Retrospective Cohort Study.

PURPOSE: To evaluate the association between lens thickness (LT) and SRK/T refractive prediction error following cataract surgery and to analyze its underlying mechanism. METHODS: This retrospective cohort study collected data from patients who underwent surgical treatment for age-related cataracts between January 2025 and June 2025. Patients were stratified into three groups based on LT: Group 1 (< 4.0 mm), Group 2 (4.0 ≤ LT < 5.0 mm), and Group 3 (≥ 5.0 mm). Intraocular lens (IOL) power was calculated using the SRK/T formula. Manifest refraction results were collected at ≥ 4 weeks postoperatively. Accuracy of IOL power calculation was analyzed using prediction error (PE), mean absolute error (MAE), median absolute error (MedAE), and the proportions of PE within ±0.25 D, ±0.50 D, and ±1.00 D. Correlations between LT and effective lens position (ELP) as well as postoperative refractive error were assessed. RESULTS: A total of 431 patients (431 eyes) were included, with a mean LT of 4.50 ± 0.58 mm. The overall mean PE was -0.08 ± 0.44 D, and the mean ELPerror was -0.04 ± 0.43 mm. Statistically significant differences were observed across the three LT groups for both PE (F = 25.742, p < 0.001) and ELPerror (F = 10.838, p < 0.001). ANCOVA was further performed to adjust for age, AL, ACD, and WTW. After adjustment, the LT group effect on PE remained significant (F = 14.960, p < 0.001, partial η 2 = 0.066), with adjusted marginal means of -0.260 D, -0.118 D, and 0.165 D for Groups 1-3, respectively, and Bonferroni-corrected pairwise comparisons confirming significant differences across all three groups (all p < 0.05). Group 3 (LT ≥ 5.0 mm) exhibited a positive mean PE (0.16 ± 0.45 D), whereas Groups 1 and 2 showed negative PEs. The MAE was ranked from lowest to highest as follows: Group 2 (0.33 D) < Group 3 (0.37 D) < Group 1 (0.40 D). Group 2 (4.0 ≤ LT < 5.0 mm) achieved the lowest MedAE (0.29 D), the highest proportion of PE within ±0.50 D (78.3%), and 100.0% within ±1.00 D. Significant positive linear correlations were observed between LT and PE (r = 0.331, p < 0.001) and between LT and ELPerror (r = 0.226, p < 0.001). Multivariate linear regression identified LT as the strongest predictor of PE (β = 0.490, p < 0.001), followed by ACD (β = 0.217, p = 0.012) and WTW (β = 0.130, p = 0.031), with the model explaining 21.2% of the variance in PE. CONCLUSION: Increased deviation of LT from the mean results in larger ELP prediction errors and greater postoperative refractive error. Thin-lens eyes tended to be myopic, while thick-lens eyes tended to be hyperopic.