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Impact of pupil dilation on IOL power calculation based on biometric measurements with Heidelberg Anterion
Sara Marquina-Martín1,2, Francisco J Segura-Calvo3,4, Martín Puzo-Bayod5,3
1GIMSO, Institute for Health Research Aragón, University Hospital Miguel Servet, Po de Isabel La Católica, 1-3, 50009, Zaragoza, Spain. saramarqu@hotmail.com.
Purpose:
To evaluate the impact of pharmacologic pupil dilation (PD) on biometric measurements and intraocular lens (IOL) power calculation using different generation formulas in patients undergoing cataract surgery.
Methods:
This prospective study included 126 eyes from 75 patients. Biometric data were obtained before and after pharmacologic dilation using the Anterion Swept-Source OCT biometer (Heidelberg Engineering). Parameters recorded included axial length (AL), mean keratometry (Km), anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WTW) distance. IOL power was calculated using six formulas: SRK/T, Haigis, Barrett Universal II (BUII), Kane, Hoffer QST, and Okulix. Statistical comparisons of biometric values and predicted IOL power before and after dilation were conducted using mixed-effects models.
Results:
No significant changes were observed in AL, CCT, LT or Km after dilation. However, ACD, WTW distance and PD showed statistically significant increases (both p < 0.01). IOL power estimations based on SRK/T, Haigis, Hoffer QST, BUII and Kane were not significantly affected after dilation. In contrast, Okulix formulas demonstrated statistically significant variations in calculated IOL power post-dilation (p < 0.0001).
Conclusions:
Pharmacologic pupil dilation induces changes in ACD and WTW measurements obtained using the Anterion Swept-Source biometer, thereby influencing IOL power estimation in formulas incorporating these parameters. Ray-tracing Okulix formula is more sensitive to dilation, whereas third-generation formulas remain more stable. Consistency in pupil status during biometry acquisition is essential to ensure refractive predictability.
