Does Surgical Sequencing Influence The Accuracy Of The Escrs Online Iol Calculator In Eyes Undergoing Phacoemulsification And Trabeculectomy?

To compare the prediction error and refractive accuracy of the ESCRS online IOL calculator among eyes undergoing combined phacoemulsification–trabeculectomy, sequential surgery (trabeculectomy followed by phacoemulsification), and phacoemulsification alone, and to determine whether surgical timing influences predictive performance.

Zonguldak Bülent Ecevit University Department of Ophthalmology, Zonguldak-Türkiye

This retrospective comparative study included 150 eyes (150 patients) divided into three groups (n=50 each):
Group 1, combined phacoemulsification–trabeculectomy performed in the same session;

Group 2, phacoemulsification performed at least 3 months after prior trabeculectomy;

Group 3, phacoemulsification alone.
Preoperative optical biometry was obtained using the Nidek AL-Scan, and IOL power was calculated with the SRK/T formula.Using the ESCRS calculator, EVO 2.0, Kane, Hill-RBF, Hoffer QST, and Cooke K6 were evaluated.According to postoperative 1st month refraction refractive performance was assessed including mean prediction error(MPE), mean absolute error(MAE), median absolute error(MedAE), and percentages within ±0.50, ±1.00,and ±2.00 D.

In Group 1 (combined surgery), Hill-RBF and Hoffer QST showed the lowest MedAE (0.71 D), whereas SRK/T yielded the lowest MAE (0.81 D); no significant differences were observed in ±0.50 D accuracy.

In Group 2 (sequential surgery), SRK/T demonstrated superior performance, with the lowest MedAE (0.49 D) and MAE (0.82 D), and the highest proportion within ±0.50 D (57.9%) (p < 0.001).

In Group 3 (phacoemulsification alone), Hoffer QST achieved the lowest MedAE (0.35 D), and MAE (0.51 D), while Hill-RBF provided the highest ±0.50 D accuracy (68%) (p < 0.001)

Overall, based on MAE, predictive accuracy was best in Group 3 and worst in Group 1, while ±0.50 D accuracy ranked as Group 3> Group 2 > Group 1.

Prior or concurrent trabeculectomy may negatively affect the predictive accuracy of contemporary IOL calculation formulas. The reduced refractive precision, particularly in the combined surgery group, may result from postoperative changes in effective lens position or axial length. Most fourth- and fifth-generation formulas are developed using biometric data from normal cataract eyes. Structural alterations after trabeculectomy may therefore limit the performance of regression- and AI-based models, leading to greater refractive error than with conventional formulas such as SRK/T and a lower rate of target refraction achievement.