Comparison of Visual, Refractive and Aberration Measurements of INTACS versus Toric ICL Lens Implantation; A Four-year Follow-up

This study was performed to evaluate the visual, refractive, and aberration measurement results of 2 implants, including Intacs Intracorneal Ring Segments (ICRS) and phakic Toric Implantable Collamer Lens (TICL), in patients with moderate Keratoconus (KCN). In this retrospective cross-sectional study, 30 patients with KCN with a mean age of 29.83 years were included in 2 groups, including the Intacs Intracorneal Ring Segments (ICRS) group and the phakic Toric Implantable Collamer Lens (TICL) group. Preoperative data as well as 6-month, 1-, 2-, 3- and 4-year follow-up data after the operation were collected and analyzed with the SPSS software (ver. 23.0, SPSS, Inc., Chicago, IL), using the paired t-test, independent t-test, repeated measures Analysis of Variance (ANOVA), and one-way ANOVA. This study included 30 patients with KCN with a mean age of 29.83 years and range of 25 to 35 years, including 17 males with a mean age of 30.11 years and 13 female with a mean age of 29.25 years. Except for preoperative Uncorrected Distance Visual Acuity (UCDVA), Spherical Equivalent (SE) and astigmatism, there was a significant difference between the 2 groups regarding other variables. The TICL group had a significantly better UCDVA and Best Corrected Distance Visual Acuity (BCDVA) in all post-operative follow-ups, and SE and astigmatism values were significantly lower in all post-operative follow-ups when compared with the ICRS group. There was a significant reduction in corneal and total coma as well as internal trefoil aberrations (P<0.01, P<0.01, and P=0.014, respectively) in the ICRS group, and TICL led to a significant reduction in internal trefoil aberration with P<0.03. Comparison of the 2 groups revealed a significant difference in corneal spherical (P<0.01) and total coma (P=0.02) aberrations and no significant differences in other HOA. Both ICRS and TICL are useful in patients with moderate KCN. However, TICL appears to have more stable and predictable vision results.