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.
Nagoya Eye Clinic, Nagoya, Japan.
Interventional case series.
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 NK-formula version 3 (NK-formula V3). Eighty-five 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 AS-OCT to validate the NK-formula V3.
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%), seven (8.2%), and one (1.2%) eye were in the moderate, low, and high vault categories, respectively. The mean difference between the achieved and predicted vault was 0.064±0.190 (range: -0.264–0.742) mm for the NK-formula V3 and 0.176±0.217 (range: -0.254–0.907) mm for the NK-formula V2.
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.