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A Comparison Between Monofocal and Multifocal Intraocular Lenses in the Influence of Pupil Dilation on Target Postoperative Refraction

Purpose: The aim of this study was to compare the influence of pupil dilation on power calculation formulas for third- (Hoffer Q, SRK/T) and fourth- (Haigis, Holladay3) generation intraocular lens (IOL) between monofocal and multifocal IOLs. Design: Retrospective, comparative study. Methods: We analyzed 280 eyes (162 monofocal, 118 multifocal; mean patient age: 72.9 ± 7.7 years; 41.25% male). Anterior chamber depth (ACD) and lens thickness (LT) were measured. Predicted postoperative refraction (PPR) and recommended IOL power were calculated using third- and fourth-generation formulas pre- and post-dilation. We evaluated the mean absolute change (MAC) in PPR, change in recommended IOL power per formula, and mean change in ACD and LT between pre- and post-dilation, for both monofocal and multifocal IOLs. Results: ACD and LT showed significant changes post-dilation. The MAC in PPR was significantly higher with fourth-generation formulas than that with third-generation formulas, for both IOLs, and more so for multifocal IOLs. For both IOLs, the PPR change correlated positively with ACD changes, but negatively with LT changes, for fourth-generation formulas. Multifocals correlated significantly stronger with LT than monofocals. When using fourth-generation formulas post-dilation, the recommended IOL power changed more frequently in multifocals than in monofocals, although not significantly. Conclusions: Pupil dilation did not influence third-generation formula calculations for both IOL types, but did affect PPR and recommended IOL power when using fourth-generation formulas, and more so for multifocals. Considering pupil dilation effects on monofocal and multifocal parameters is vital for accurate IOL calculation.