Effect of Intraocular Lens Power Calculation Formula Optimization in the Sum-of-Segments Optical Biometer

Takashi Kojima,1,2 Akeno Tamaoki,2 Kazuo Ichikawa,3 Yuya Satoh,4 Ryota Tomemori,5 Keizo Watanabe,6 Asato Hasegawa,2 Ayako Sawaki,2 Tatsushi Kaga2 1Department of Ophthalmology, Nagoya Eye Clinic, Nagoya, Aichi, Japan; 2Department of Ophthalmology, Japanese Community Healthcare Organization Chukyo Hospital, Nagoya, Aichi, Japan; 3Department of Ophthalmology, Chukyo Eye Clinic, Nagoya, Aichi, Japan; 4Department of Ophthalmology, Satoh Yuya Eye Clinic, Sendai, Miyagi, Japan; 5Department of Ophthalmology, Tomemori Eye Clinic, Hashimoto, Wakayama, Japan; 6Department of Ophthalmology, Minami Osaka Eye Clinic, Sennangun, Osaka, JapanCorrespondence: Takashi Kojima, Email [email protected]: We evaluated the effect of optimization of the intraocular lens (IOL) power calculation formula SRK/T and Barrett Universal II (BU II) in long eyes (≥ 26 mm: group L) and short eyes (≤ 22 mm: group S) using axial length calculated from segmented refractive indices (SRI).Setting: Multicenter study at five sites in Japan.Design: Retrospective observational study.Methods: This study included 461 eyes of 461 patients (mean age 73.8 ± 8.4 years) who underwent cataract surgery. The predicted refractive error (PRE) was compared between the SRI (ARGOS) and the equivalent refractive index (ERI) biometers (IOLMasterTM 700). The patients were randomly divided into two groups, a learning group and a validation group. The optimization constants were determined in the learning group, and the optimization constants were subsequently applied to the validation group and compared with the ERI biometer results.Results: Using both SRK/T and BU II, the validation group’s PRE using optimization constants for the SRI biometer in group L was significantly smaller than that using the ERI biometer (p< 0.001, p< 0.01). In group L, the arithmetic PRE of Barrett UII formula with SRI showed a significant improvement after optimization compared to before optimization (p< 0.0001). In group S, the arithmetic PRE of SRK/T and Barrett UII formula with SRI showed a significant improvement (p< 0.0001, p< 0.0001).Conclusion: In long and short eyes, the current study revealed that optimization of the SRK/T and Barrett formula constants for the SRI biometer was beneficial to achieve accurate refractive outcomes after cataract surgery.Keywords: segmented refractive index, intraocular lens power calculation, Sanders-Retzlaff-Kraff theoretic, Barrett universal II, optimization