Safety and Efficacy of Posterior Chamber Phakic Implantable Collamer Lenses in Patients with Keratoconus: A Systematic Review and Meta-Analysis.

Purpose: To assess the safety and efficacy of phakic implantable collamer lenses (ICLs) in patients with keratoconus.

Design: Systematic review and meta-analysis.

Methods: We conducted a pre- and postintervention single-arm systematic review and meta-analysis in line with guidelines from the Cochrane Collaboration and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 Consensus Statement. We searched five electronic databases and the grey literature for any studies evaluating ICLs in the setting of keratoconus. Our primary outcomes were the corrected distance visual acuity, uncorrected distance visual acuity, and manifest cylinder astigmatism. Secondary outcomes included uncorrected near visual acuity, spherical equivalent, refractive astigmatism, higher-order aberrations, endothelial cell density, intraocular pressure, and incidence of adverse events. We summarized our analyses by calculating standardized mean differences (SMDs) with associated 95% confidence intervals (CIs) using random-effects meta-analysis.

Results: Sixteen observational studies, totaling 397 eyes, were eligible. Postoperatively, there was no statistically significant improvement in corrected distance visual acuity (SMD: -0.97, 95% CI: -1.99 to 0.05, P < .06); there was a statistically significant improvement in uncorrected distance visual acuity (SMD: -5.41, 95% CI: -0.704 to -3.78, P < .05), manifest cylinder (SMD: 2.27, 95% CI: 1.83-2.70, P < .05), spherical equivalent (SMD: -4.66, 95% CI: -5.63 to 3.68, P < .05), and refractive astigmatism (SMD: 2.22, 95% CI: 1.03-3.41, P < .05). No significant adverse events occurred.

Conclusions: Use of ICLs in patients with keratoconus is safe and effective, resulting in significant improvements in a myriad of visual and refractive measures. Our results remain limited by the observational design of included studies as well as the limited follow-up duration.