Intraocular lens power calculation adapted to sutureless scleral fixation with the Yamane technique

To assess reliability of different intraocular lens (IOL) power calculation formulas in secondary IOL implantation with sutureless scleral fixation (Yamane technique).

San Maurizio Hospital, Bolzano, Italy; University of Salerno, Italy.

Retrospective cohort study.

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.

All formulas reported a myopic shift of MEs with IOLCon constants (ranging from -0.43 to -0.31 D, all P < .050). No statistically significant differences among methods in MedAE were reported with both IOLCon and optimized constants (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 < .001), with comparable MedAE and percentages of eyes with PE less than ±0.50/±1.00 D (all P > .050).

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.