Utilization of the Reinstein ICL Sizing Formula With Hand-held Ultrasound Biomicroscopy Measurements

Purpose: To evaluate the accuracy of the Reinstein formula with hand-held ultrasound biomicroscopy (UBM) measurements for sizing of the Implantable Collamer Lens (ICL). Methods: A total of 107 myopic eyes of 57 patients implanted with the ICL were included in the study. The size of the ICL was selected based on the manufacturer's recommendations. Agreement between the vault predicted by the Reinstein formula and the vault measured postoperatively was analyzed with Bland-Altman plots. Results: A total of 95% and 81% of patients had a postoperative vault ranging from 150 to 1,000 and 250 to 750 μm, respectively. The mean vault predicted by the Reinstein formula and the postoperative vault in the current study were 580 ± 181 and 547 ± 200 μm, respectively. The size recommendations of the Reinstein formula and the formula provided by the manufacturer, the Kojima formula, and the Dougherty formula overlapped in 50%, 57%, and 49% of eyes, respectively. Conclusions: The results show that the Reinstein formula combined with a hand-held UBM provides reliable sizing predictions of the ICL. However, considering that robotic UBM measurements have demonstrated a narrower range of deviation in predicting vault depth in previous studies, a direct comparison study between robotic UBM and hand-held UBM measurements is necessary to fully assess the limitations of combining hand-held UBM with the Reinstein formula. [ J Refract Surg . 2024;40(3):e142–e147.]