Evaluation of implantable collamer lens sizing developed by reviewing the horizontal compression-vault coefficient.

PURPOSE: To evaluate the implantable collamer lens (ICL)-sizing method using the partial regression coefficient of the implanted ICL size to review the conventional horizontal compression coefficient and match the results of clinical observation.

SETTING

Nagoya Eye Clinic, Nagoya, Japan.

DESIGN

Interventional case series.

METHODS

Patients who underwent ICL V4c implantation to correct myopia and myopic astigmatism were enrolled. The stepwise multiple regression analysis used achieved vault as a dependent variable and preoperative biometric parameters as explanatory variables. The partial regression coefficient of the implanted ICL size was obtained to develop the optimal ICL-sizing formula, the Nakamura-Kojima formula version 3 (NK-formula V3). 85 eyes of 45 patients were implanted with an ICL size recommended by the NK-formula V3. At 3 months postoperatively, the achieved vault was measured using anterior segment optical coherence tomography to validate the NK-formula V3.

RESULTS

The study enrolled 174 patients (174 eyes). The partial regression coefficient of the implanted ICL size adopted as the compression-vault coefficient in the multiple regression equation predicting the vault was 0.729. To validate the NK-formula V3, 77 (90.6%), 7 (8.2%), and 1 (1.2%) eyes were in the moderate-vault, low-vault, and high-vault categories, respectively. The mean difference between the achieved and predicted vaults was 0.064 ± 0.190 (range: -0.264 to 0.742) mm for the NK-formula V3 and 0.176 ± 0.217 (range: -0.254 to 0.907) mm for the NK-formula V2.

CONCLUSIONS

As in vivo coefficient measurement experiments are not possible, the partial regression coefficient is the best option for developing a formula to predict the optimal ICL size.