Implantable Collamer Lens Sizing Method Based on Swept-Source Anterior Segment Optical Coherence Tomography

To develop and evaluate the accuracy of a size-determination formula using anterior segment optical coherence tomography (AS-OCT) parameters.Interventional case series.This study included 46 eyes of 23 patients with implantable collamer lens (ICL). Preoperatively, the anterior segment parameters were measured using high-frequency ultrasound biomicroscopy and AS-OCT. Three months postoperatively, the vaults were measured and the optimal ICL size was calculated using a previously published method. Stepwise multiple regression analysis was performed using the optimal ICL size as a dependent variable; the NK-formula was obtained. Thereafter, 35 eyes of 18 patients were implanted with ICL after the size was calculated using the NK-formula. Vaults measured at 3 months postoperatively were used to evaluate the accuracy of the NK-formula.The distance between scleral spurs (ACW) and crystalline lens rise (CLR) were selected as significant parameters for the regression model (R2 = 0.68, P < .05). There were 25 (71%), 8 (23%), and 2 (6%) eyes in the moderate, high, and low vault categories, respectively. Using the STAAR nomogram for ICL sizing, 24 eyes (69%) were fitted in the moderate vault. The mean absolute error of the predicted vault was significantly lower with the NK-formula (0.190 ± 0.129 mm) than with the STAAR nomogram (0.331 ± 0.235 mm, P = .002, paired t test).AS-OCT is useful for ICL size determination, because it calculates the anterior segment parameters using automatic analysis. The NK-formula shows higher accuracy for predicting vault than the STAAR nomogram.