Visual outcomes and corneal biomechanics after V4c implantable collamer lens implantation in subclinical keratoconus

Purpose: To quantitatively evaluate the safety, efficacy, stability, predictability, and corneal biomechanical parameters after V4c implantable collamer lens (ICL) implantation in subclinical keratoconus. Setting: Xi'an AIER Eye Hospital, Xi'an, China. Design: Retrospective case series. Methods: Patients undergoing V4c ICL/toric ICL implantation were examined. Scheimpflug tomography (Pentacam) was used to measure the Belin-Ambrosio enhanced ectasia total deviation index. Dynamic Scheimpflug biomechanical analysis (CorVis ST) was used to measure the corneal biomechanical parameters and Corvis Biomechanical Index. The Tomographic and Biomechanical Index was measured by combined Pentacam with CorVis ST. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, and adverse effects were also investigated. Results: A total of 60 eyes of 60 patients (mean age ± SD, 27.21 ± 7.24 years) were included. The mean preoperative UDVA and CDVA were 1.08 ± 0.25 and 0.12 ± 0.04 logarithm of the minimum angle of resolution (logMAR) (20/230 and 20/28 Snellen VA), respectively. After 2 years, the mean postoperative UDVA and CDVA were 0.01 ± 0.06 and −0.05 ± 0.03 logMAR (20/20 and 20/18 Snellen VA), respectively. The mean difference between the intended and achieved spherical equivalent (SE) was −0.08 ± 0.47 diopter (D), and the SE was within ±1.00 D of the intended correction in 57 eyes (95%), and 58 eyes (97%) had astigmatism less than 0.50 D. The refractive results were stable 2 years postoperatively, and the corneal biomechanical parameters returned to their preoperative levels at 3 months. Conclusions: The V4c ICL/toric ICL in subclinical keratoconus offered predictable correction of SE refractive error. Refractive results and corneal biomechanics were stable at the 2-year follow-up.