Efficacy of Variable-thickness Sinusoidal Intracorneal Ring Segments in Management of Keratoconus: A Multicenter Retrospective Study

Purpose: To evaluate the outcomes of implanting variable thickness intracorneal ring segments (Vt-ICRS) in the treatment of keratoconus. Patients and methods:A retrospective multicenter study from seven centers in five different countries, including patients who underwent Vt-ICRS implantation with a minimum follow-up period of 2 months.Results: A total of 56 eyes from seven surgeons were included in the analysis, with a mean follow-up of 20.8 ± 21.8 months.The mean patient age was 31.1 ± 12 years (range, 17-69 years).Most procedures (85.4%) utilized a 5 mm arc, while the remaining 14.6% using a 6 mm arc.Arc lengths were distributed as follows: 140° (3.7%), 150° (24.1%), 160° (44.4%), and 180° (27.8%).Arc thickness combinations included 150/250 µm (58.3%), 200/300 µm (27.1%), 250/350/250 µm (10.4%), and 200 µm (4.2%).Corrected distance visual acuity (CDVA) improved significantly from 0.345 ± 0.172 to 0.716 ± 0.223 (p < 0.001).The mean Big D value decreased from 8.47 ± 2.77 to 7.46 ± 2.81 (p < 0.001), and vertical coma improved from -1.54 ± 3.35 to -0.524 ± 1.56 (p = 0.018).The mean Kmax decreased from 54.2 ± 3.52D preoperatively to 51.0 ± 4.11D postoperatively (p < 0.001), K1 from 45.7 ± 4.10D to 44.7 ± 5.04D (p < 0.001), and K2 from 50.1 ± 5.48D to 47.6 ± 5.47D (p < 0.001).Conclusion: Preliminary results showed improvement in all measured outcomes; however, a longer follow-up period is needed, and comparison between classic ICRS should be taken into consideration in future studies.