Posters

Intraocular collamer lenses: association between vaulting and postoperative refraction

Poster Details

First Author: P.Serra SPAIN

Co Author(s):    S. Cerpa Manito   A. Sánchez Trancón   O. Torrado Sierra   A. Baptista           

Abstract Details

Purpose:

Intraocular Collamer lenses are phakic lenses used for the correction of high refractive errors. The calculation of the ICL power depends on the expected postoperative position of the lens, i.e. an expected vault. The vault is the distance between the anterior crystalline lens surface and the ICL posterior surface. Thus, in the case the vault differs from the expected value used in the ICL calculation, the implanted ICL will no longer be adjusted to the desired refraction. This study aims to assess the association between postoperative manifest refraction and the vault in patients implanted with spherical myopic ICL.

Setting:

Ophthalmology Clinic Vista Sánchez Trancón, Badajoz, Spain

Methods:

This retrospective case series analyzed 110 eyes (71 patients) implanted with myopic ICL (EVO-V4c, STAAR Surgical AG) between 2012 and 2017. The ICL's size and power were ordered according to the manufacturer's Online Calculation & Ordering System (OCOS). Three months post-surgery the vault and postoperative manifest refraction was assessed using the AS-OCT Visante (Carl-Zeiss Meditec) and an auto refractometer Topcon KR-8900 (Topcon Corporation). The post-operative spherical-equivalent (SE) was calculated as the difference between the postoperative manifest SE and the predicted SE provided by the OCOS. The clinical findings were compared to paraxial ray tracing using a theoretical model eye.

Results:

Paraxial ray-tracing predictions show a linear association between postoperative refraction and vault. Moreover, predictions indicate that for every 500μm in vault variation the postoperative sphere may vary 0.2DS and 0.4DS respectively for -6.0 and -18.0DS ICLs. The correlation between vault and postoperative-SE (R=0.345 p<0.001), for an average of -8.70DS ICL, showed a 0.2DS variation in the postoperative-SE for a 500μm variation in the vault. Eyes with higher vaults (>750μm) had a mean postoperative-SE 0.17DS more hyperopic than the group with vaults between 250-750μm (p=0.027). Furthermore, the effect of the vault on postoperative-SE was stronger in eyes with more myopic ICLs.

Conclusions:

This study corroborates the theoretical predictions regarding the dependency of the postoperative refractive error on the vault. ICLs with higher vaults present a trend towards a hyperopic over-refraction, more pronounced in high myopic lenses. Although the magnitudes of the refractive shifts are small, patients with low accommodative amplitude and presenting a high vault may present more symptomatology in near tasks. These findings may guide the surgeon in selecting the most appropriate ICL power taking into account the amount of expected vault.

Financial Disclosure:

None