Use of the Crystalline Lens Equatorial Plane as a New Parameter for Predicting Postoperative Intraocular Lens Position

Purpose: To assess whether preoperative crystalline lens equatorial plane (LEP) reliably predicts the postoperative position of the intraocular lens (IOL). Design: Comparative, interventional case series. Methods: Phacoemulsification and IOL implantation (Group I, ZCB00; Group II, EC-1PAL; and Group III, CT Asphina) were performed for 104 eyes. Lens geometry parameters, including LEP, were obtained from a femtosecond laser cataract surgery system prior to surgery. LEP was defined as the distance from the front surface of the cornea to the equatorial plane of the crystalline lens. Postoperative anterior chamber depth (ACD) was measured using a Scheimpflug camera. Median absolute error was calculated using an optical ray-tracing method that incorporated LEP into an individualized eye model, and the results were compared with those from the Haigis formula. Results: Preoperative ACD (3.27 ± 0.39 mm [R = 0.428], 3.30 ± 0.47 mm [R = 0.591], and 3.49 ± 0.39 mm [R = 0.373] in Groups I, II, and III, respectively) and LEP (4.81 ± 0.29 mm [R = 0.570], 4.84 ± 0.27 mm [R = 0.634], and 4.97 ± 0.23 mm [R = 0.565] in Groups I, II, and III, respectively) were found to have significant positive correlations with postoperative ACD (5.24 ± 0.40 mm, 5.02 ± 0.31 mm, and 5.19 ± 0.26 mm in Groups I, II, and III, respectively). Stepwise regression analysis showed that postoperative ACD was significantly correlated with LEP in all groups. Median absolute errors predicted by the ray-tracing method using LEP were smaller than those from the Haigis formula in all groups. Conclusions: LEP is a promising measure from preoperative crystalline lens geometry and could serve as a new parameter to improve refractive outcomes in cataract surgery.