[Accuracy comparison of intraocular lens power calculation formulas in cataract patients with axial length greater than 28 mm undergoing phacoemulsification with capsular tension ring implantation].

Objective: To evaluate the accuracy of the Barrett Universal Ⅱ, Haigis, and SRK/T formulas for intraocular lens (IOL) power calculation in cataract patients with axial length >28 mm undergoing phacoemulsification combined with capsular tension ring implantation. Methods: A retrospective case series study was conducted. Data from 26 eyes (26 patients) with cataract (axial length>28 mm), treated at the Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, from January to October 2023 were analyzed. Patients had a median age of 59 years (interquartile range: 51-63), with 14 males and 12 females. All patients underwent biometric measurements using the IOL Master, had uneventful surgeries without intraoperative or postoperative complications, and completed objective refraction at 1 month postoperatively. Primary outcomes included mean prediction error (MPE), mean absolute error (MAE), and the percentage of eyes with prediction errors within ±0.25 D,±0.50 D, and ±1.00 D. Inter-group comparisons were performed using the one-way ANOVA with Bonferroni correction, and categorical data were analyzed using the Chi-square test. Results: The Barrett Universal Ⅱ formula yielded the smallest MPE of (-0.08±0.28) D, compared to (0.35±0.43) D for Haigis and (0.31±0.47) D for SRK/T. The MAE was lowest with Barrett Universal Ⅱ (0.22 D), significantly lower than Haigis (0.43 D) and SRK/T (0.45 D) (P<0.05). Within the ±0.25 D prediction error range, Barrett Universal Ⅱ achieved 19/26 eyes (73.08%), significantly higher than Haigis (10/26, 38.46%) and SRK/T (8/26, 30.77%) (P<0.05). For the ±0.50 D range, Barrett Universal Ⅱ included 24/26 eyes (92.31%), surpassing Haigis (17/26, 65.38%) and SRK/T (16/26, 61.54%) (P<0.05). Within ±1.00 D, Barrett Universal Ⅱ achieved 26/26 eyes (100%), compared to Haigis (25/26, 96.15%) and SRK/T (24/26, 92.31%). Conclusions: In cataract patients with axial length >28 mm and capsular tension ring implantation, the Barrett Universal Ⅱ formula is recommended for its superior accuracy in IOL power calculation, with an MPE closer to zero, lower MAE, and significantly higher percentages of eyes within ±0.25 D and ±0.50 D prediction error ranges compared to Haigis and SRK/T.