Safety and efficacy of implantable phakic contact lens versus implantable collamer lens in myopia correction

Abstract Background: Phakic intraocular lenses (pIOLs) have proven to be excellent substitutes for excimer laser keratorefractive surgery in certain situations. We aimed to assess the efficacy and safety of two pIOLs, the implantable collamer lens (ICL V۴c) versus the implantable phakic contact lens (IPCL V۲), for myopic correction. Methods: In this prospective randomized clinical trial, we allocated eligible eyes with myopia > - ۶ diopters into IPCL or ICL implantation groups, each including ۱۰۰ eyes of ۱۰۰ individuals. Preoperative and postoperative assessments at ۳, ۶, and ۱۲ months included measurements of the spherical equivalent (SE), uncorrected distance visual acuity (UCDVA), best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), maximum keratometry (K۱), minimum keratometry (K۲), mean keratometry (Kmean), anterior chamber depth (ACD), anterior chamber angle (ACA), and endothelial cell density (ECD). Results: The groups had comparable demographic characteristics and baseline visual and anatomical values (all P > ۰.۰۵). The UCDVA, BCDVA, and SE of the two groups were comparable at baseline and at all postoperative follow-up examinations (all P > ۰.۰۵). Both groups experienced significant improvements in UCDVA, BCDVA, and SE at three months postoperatively (all P = ۰.۰۰۱), and measurements remained stable for up to ۱۲ months. Keratometry readings were comparable between the groups over the follow-up period and remained unchanged at all visits (all P > ۰.۰۵). The ACA in the ICL group was significantly decreased at three months postoperatively (P = ۰.۰۰۱) and then widened significantly at ۶ and ۱۲ months (both P = ۰.۰۰۱). In the IPCL group, the postoperative ACA was significantly decreased at three months (P = ۰.۰۰۱) and was comparable to that in the ICL group (P > ۰.۰۱). However, at the ۶- and ۱۲-month postoperative visits, the ACA was significantly narrower in the IPCL group than in the ICL group (both P = ۰.۰۰۱). The ACD in both groups was decreased at three months postoperatively (both P = ۰.۰۰۱) and remained stable until the end of the study. The ECD remained comparable between the groups at all postoperative visits (all P > ۰.۰۵). We did not observe a significant ECD reduction in either group at any postoperative follow-up visit (all P > ۰.۰۵). We encountered no serious complications in either group. Conclusions: ICL and IPCL had comparable safety and efficacy outcomes in terms of anterior chamber morphometrics, visual and refractive results, and corneal parameters. Further multicenter randomized clinical trials with longer follow-up periods, larger sample sizes, and measurement of additional anterior chamber and corneal morphometrics, vault, and other vision parameters are needed to verify these findings.