Comparison of formulas in the implantable collamer lens vault prediction

To compare the predictability of different formulas in the postoperative vault of an implantable collamer lens (ICL) surgery and assist physicians for formula selection in ICL implantation. This is a retrospective study. Patients who underwent ICL implantation between August 31, 2021 and October 29, 2021 at our clinic were reviewed. The clinical data, predicted ICL sizes and vaults, actual ICL size implanted and vaults at 1 month after surgery, and corresponding prediction formulas used were collected and analyzed. This study included 140 eyes from 72 patients (15 males and 57 females). Differences between ICL sizes recommended by the Visian ICL Online Calculation & Ordering System (OCOS) and NK formula (Version. 3) or KS formula (Version. 4) were statistically significant (P < .0001), except for the recommended ICL sizes between the NK and KS formulas (P > .05). Better consistency between predicted ICL vaults and achieved ICL vaults was observed when using the KS formula compared to the NK formula. The actual ICL vaults were 250 to 750 μm at 1 month after surgery in 66.4%, 76.5%, and 80.5% eyes of the OCOS, NK, and KS groups, respectively. There was significant difference between the OCOS and KS groups (P < .05), especially in the 12.6 mm ICL group. The KS formula is the most accurate formula for recommending an ICL size and vault prediction when compared to the NK formula and OCOS. Further studies for a more accurate formula are warranted.