Correlation between Preoperative Sizing of Implantable Collamer Lens (ICL) by White-to-white and Sulcus-to-sulcus Techniques, and Postoperative Vault Size Measured by Sheimpflug Imaging

Purpose: To evaluate correlations between preoperative sizing of Implantable Collamer Lens (ICL) by white-towhite and sulcus-to-sulcus techniques, and postoperative vault size measured by Sheimpflug imaging. Setting: Persian Eye Clinic, a private eye clinic located in Isfahan city, Iran Design: Prospective, nonrandomized clinical trial Methods: This prospective clinical trial included 63 eyes of 49 patients who were candidates for implantation of Implantable Collamer Lens (ICL). Preoperatively, both WTW and horizontal STS were measured in all eyes. Patients were divided into 3 groups based on ICL sizing method used for lens ordering (WTW group, STS group and M group). In the third group ICL size was determined according to the average of WTW and STS. Postoperative vault was measured 3 months after surgery by means of Scheimpflug tomography. Results: Mean WTW and STS diameters were 11.68 ± 0.52 mm and 11.82 ± 0.74 mm, respectively. Linear regression analysis found a statistically significant correlation (p=0.004) between them, however, there was a large degree of scatter as indicated by R2=0.128. Ideal vault (400-550 μm) was achieved in 20% of WTW, 28% of STS and 13% of M group. There was no statistical difference in achieved ICL vault between three groups (p=0.273). Based on the statistical analysis of our results, we developed equations for better optimization of ICL sizing. Conclusion: According to our results, there is poor correlation between STS and WTW. Sulcus-to-sulcus measurement did not significantly improve ICL sizing, and Sizing based on each technique alone may result in poor vaults in considerable number of cases. Comparison of WTW and STS to postoperative vaults provided regression models that allowed the development of new equations. Farther studies are needed for evaluating accuracy and reliability of these models.