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 m (58.3%), 200/300 m (27.1%), 250/350/250 m (10.4%), and 200 m (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.