To evaluate the vault change after implantable collamer lens (ICL) size exchange according to the preoperative vault.

In 14 eyes of 13 patients, the vault change after ICL exchange operation due to unideal vault was compared in 2 groups, the smaller ICL exchanged group and larger ICL exchanged group.

In 6 out of 14 eyes, the ICL was exchanged to a 0.5 mm smaller size and the vault was changed from 1.38 mm (1.18-1.70) to 0.71 mm (0.51-0.92) ( p = 0.03). In 8 eyes, the ICL was exchanged to a 0.5 mm bigger size and the vault was changed from 0.07 mm (0.03-0.13) to 0.50 mm (0.12-1.01) ( p < 0.01). The exchange operation was performed at 3.5 postoperative days (1-6) if the ICL was exchanged to 1 step smaller size, but the exchange operation was performed at 135 postoperative days (90-660) if the ICL was exchanged to 1 step bigger size ( p < 0.01).

ICL exchange to 1 step smaller or bigger size is an effective method to correct unideal postoperative vault to a more ideal vault size. The exchange to 1 step smaller size ICL tended to be performed sooner.