Comparison of IOL Power Prediction Formulas in Pediatric Cataract Surgery
Authors: Ninglu Weng 1, Michael Richards2, Ian Clark2. 1Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 2Department of Ophthalmology, Max Rady College of Medicine, University of Manitoba.
Author Disclosures: N. Weng: All other investments or relationships that could be seen by a reasonable, well-informed participant as having the potential to influence the content of the educational activity; Name of for-profit or not-for-profit organization(s); University of Manitoba Max Rady College of Medicine, University of Manitoba Max Rady College of Medicine. All other investments or relationships that could be seen by a reasonable, well-informed participant as having the potential to influence the content of the educational activity; Description of relationship(s); Summer Research Program Stipend, (Possible) Conference Travel Bursary. M. Richards: None. I. Clark: None.
Purpose: Selecting the most appropriate intraocular lens (IOL) power in pediatric cataract surgery involves challenges that are unique from those of adult surgery. Factors which differentiate IOL selection in children include the need to account for future eye growth; precisely unknown but disproportionate average differences in axial length (AL), anterior chamber depth, and corneal shape; as well as reliance on ultrasound rather than optical biometry. The main purpose of this study was to determine which of three commonly-used IOL power calculation formulas best predicts 4-6-week postoperative refraction in pediatric IOL implantation using ultrasound biometry.
Study Design: Retrospective comparative analysis.
Methods: This study included all patients ≤12 years old that underwent early-onset cataract extraction with either primary and secondary posterior chamber IOL implantation at HSC Children’s Hospital in Winnipeg, Manitoba between 2009 and 2021. Patient characteristics, ocular biometry measurements, surgical details, and postoperative outcome data were obtained from the ultrasound machine databases and clinic charts. Actual postoperative refractive outcomes at 4-6 weeks were compared to the predicted outcomes according to three IOL power calculation formulas, namely: Holladay-1, Hoffer-Q, and SRK/T. Signed errors (SnEs) were calculated as the difference between the predicted and actual refractive outcomes. SnEs and absolute errors (AbEs) were analyzed to compare formula accuracy and precision, respectively. Follow-up analysis correlated the SnEs and AbEs of each formula with the biometry values included in IOL power calculation (AL and mean keratometry) and other continuous variables (age at surgery and IOL power).
Results: 68 eyes of 46 consecutive eligible patients were identified. Exclusions were made for 5 eyes missing primary outcome data. The SnEs of each formula did not significantly deviate from a target refractive error of 0. No statistically significant differences in precision ( F (1.218, 81.616) = 3.541, p = 0.055) nor accuracy ( F (1.258, 84.287) = 0.963, p = 0.349) were found between the three formulas. Correlation analysis revealed statistically significant associations between Holladay-1 and Hoffer-Q AbE with AL; the AbE of all three formulas with IOL power; Hoffer-Q SnE with IOL power; and SRK/T SnE with mean keratometry values.
Conclusions: Although no statistically significant differences were detected between primary outcomes, the significant secondary findings and relatively high magnitude of mean AbEs may suggest importance differences within a heterogeneous pediatric cataract population. Stratifying patients by certain preoperative variables could potentially result in differential outcomes when applying the same formulas. Given the extent of data collected for each patient, performing subgroup analyses may represent a reasonable follow-up to this study.