AIM: To compare clinical outcomes and refractive stability of implantable collamer lens (ICL) implantation and femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) for high myopia correction. METHODS: The Optical Quality Analysis System (OQAS) was used to evaluate clinical outcomes objectively after operation for high myopia correction. We compared the two procedures in terms of 1-year changes in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), safety index, efficacy index, spherical equivalent, modulation transfer function (MTF) cutoff frequency, strehl ratio (SR) and objective scatter index (OSI). RESULTS: At 1y postoperatively, the safety indices were 1.33±0.27 in ICL group, and 1.17±0.24 in FS-LASIK group. 39.58% in the ICL group and 27.59% in the FS-LASIK group gained CDVA in 2 lines or better than that in preoperative CDVA. The efficacy indices were 1.28±0.22 in ICL group, and 1.13±0.26 in FS-LASIK group. The changes of spherical equivalent from 1wk to 1y postoperatively was -0.12±0.37 D in ICL group, and -0.79±0.58 D in FS-LASIK group (P<0.05). Spherical equivalent within ±0.50 D was achieved in 97.92% in ICL group and 68.97% in FS-LASIK group. MTF cutoff frequency were higher with ICL as compared to FS-LASIK (P<0.05) at each postoperative follow-up stage; for postoperative 1mo later, SR was statistically significant difference between two groups (P<0.05); with no statistically significant difference in OSI between two groups (P>0.05) in postoperative 3mo later. CONCLUSION: ICL implantation and FS-LASIK procedures both provide good safety and predictability in high myopia correction. ICL implantation provides better clinical outcomes and refractive stability than FS-LASIK.

BackgroundTo derive and validate a novel vault prediction formula to improve the predictability and safety of implantable collamer lens (ICL) implantation.MethodsThirty-five patients (61 eyes) with previous posterior chamber intraocular lens implantation were included. Various parameters, such as horizontal-visible iris diameter (HVID), photopic pupil diameter (PPD), axial length (AL), white-to-white (WTW), anterior chamber width (ACW), angle-to-angle (ATA), crystalline lens rise (CLR), anterior chamber depth (ACD), horizontal sulcus-to-sulcus (HSTS), and ciliary sulcus angle (CSA) were measured. Vault was measured at 3 months after surgery using CASIA2 anterior segment optical coherence tomography. The formula was derived using multiple linear regression analysis and named as WH formula. It was validated in 65 patients (118 eyes) to determine the percentage of the ideal postoperative vault range and to compare the differences between the WH formula and the NK, KS, and STAAR formulas.ResultsFinal ICL size, ATA, CSA, and CLR were included in the prediction formula model (adjusted R2 = 0.67, p < 0.001). The achieved vault 1 month after the surgery was 556.19 μm ± 166.98 μm in the validation group, and the ideal vault range was 200–800 μm (92%). The difference between the achieved vault and that predicted using the WH formula was not statistically significant (p = 0.165), whereas the difference between the achieved vault and that predicted using the NK and KS formulas was statistically significant (p < 0.001 and p < 0.001, respectively). The 95% agreement limit range of the achieved vault and the vault predicted using the WH formula was narrower than those predicted using the NK and KS formulas (−295.20–258.82 μm).ConclusionThis study combined the results of optical coherence tomography and ultrasound biomicroscopy measurements of the anterior segment of the eye and incorporated ciliary sulcus morphology quantification into the prediction formula. The study derived a prediction formula for vault by combining ICL size, ATA, and CLR. The derived formula was found to be superior to the currently available formulas.

Implantable collamer lens implantation is safe and effective for highly myopic patients with peripheral primary iris and ciliary body cysts. The cysts did not change after operation in this study.