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PURPOSE: To assess reliability of different intraocular lens (IOL) power calculation formulas in secondary IOL implantation with sutureless scleral fixation (Yamane technique). SETTING: San Maurizio Hospital, Bolzano, Italy; University of Salerno, Italy. DESIGN: Retrospective cohort study. METHODS: 50 eyes of 50 patients who underwent secondary IOL implantation with Yamane technique were analyzed. Surgery was performed with a standardized technique using the needle stabilizer. Barrett Universal II, EVO-2.0, Hoffer-Q, Holladay 1, SRKT, T2, and T2.2 formulas were analyzed for mean error (ME), median absolute error (MedAE), and percentages of eyes with refractive prediction error (PE) less than ±0.50/±1.00 diopter (D). Both IOLCon and optimized constants through zeroing out the MEs were analyzed. In addition, formulas were also tested with decreased optimized-IOLCon constants (DOC) by a fixed value of -0.5. RESULTS: All formulas reported a myopic shift of MEs with IOLCon constants (ranging from -0.43 to -0.31 D, all P .050). By using DOC-0.5, all formulas reported MEs not different from zero (all P ≥ .491) and all MEs were lower than IOLCon MEs (all P .050). CONCLUSIONS: In case of out-of-the-bag IOL implantation, a systematic error independent from the applied formula but linked to surgery technique was found. Using DOC-0.5 can eliminate such a bias. The study highlights the importance of refining lens constants in case of scleral fixation, to eliminate any systematic error in IOL power calculation.
Vitto et al. (Fri,) studied this question.