Pre‐operative visual evaluation for implantable collamer lenses in highly myopic eyes

Abstract

PurposeThe aim of this study was to evaluate a clinical procedure based on trial rigid gas‐permeable () contact lenses fitting to assess the real pre‐operative visual acuity (VA) of highly myopic eyes undergoing surgery with an implantable collamer lens.MethodsHighly myopic eyes with a spectacle visual acuity (SVA) of 0.2 logMAR (6/9.6 Snellen) or worse were enrolled. A trial RGP contact lens with high dioptric power was fitted before collamer lens implantation. The trial contact lens residual refractive error was corrected by spectacle over‐refraction to estimate contact lens VA (CLVA). The three‐month post‐operative uncorrected vision and visual acuities were also measured. The safety and efficacy indices of collamer lens implantation were calculated based on pre‐operative SVA and CLVA, respectively.ResultsThe study enrolled 42 patients with 68 highly myopic eyes with a mean pre‐operative spherical equivalent of ‐16.40 ± 4.43-D. The mean pre‐operative SVA was 0.38 ± 0.19 logMAR. Pre‐operative trial RGP contact lens fitting resulted in a significant improvement of VA (2.02 ± 1.05 lines), which was statistically insignificantly different from the VA with the implantable collamer lens (2.07 ± 0.8 lines). The safety index of collamer lens implantation was 1.70 ± 0.38 in reference to the pre‐operative SVA but significantly decreased to 1.02 ± 0.17 in reference to CLVA. Similarly, the efficacy index of 1.17 ± 0.48 on SVA decreased to 0.71 ± 0.28 on CLVA.ConclusionsTrial RGP contact lens fitting was found to indicate the potential implantable collamer lens VA more accurately than spectacle refraction. Consideration should be given to the use a trial RGP contact lens as part of the pre‐operative work‐up prior to collamer lens implantation in order to provide an assessment of the patient's potential post‐operative VA.