Outcome of intrastromal corneal ring segment relative to depth of insertion evaluated with scheimpflug image

To report the results of intrastromal corneal ring segment (KeraRing; Mediphcose, Belo Horizonte, Brazil) implantation relative to depth of insertion in keratoconic patients. METHODS: In this retrospective, observational study, we evaluated 29 eyes of 27 patients with keratoconus who underwent implantation of KeraRing SI-5 with mechanical tunnel creation. In the mean follow-up of 8.8 months, all eyes underwent scheimpfluge image of pentacam (Oculus, Germany) to determine insertion depth. Based on the measured implantation depth, cases were categorized into: 40-59% thickness group, 60-79% thickness group, and ≥80% thickness group. Visual, refractive, and shape outcomes were evaluated relative to implantation depth. RESULTS: The mean insertion depth was 61.7%.We had 41.4% of cases were in the 40-59% thickness group, 51.7% in the 60-79% group, and 6.9% in the >80% group. Results were similar in 40-59% and 60-79% thickness groups: uncorrected visual acuity (UCVA) and best spectacle corrected VA (BSCVA) improved 3 and 2 lines, respectively, maximum keratometry (Kmax) decreased 2.6 D, refractive cylinder improved 2.04 D, and Q value 8 mm anterior changed by 0.35. In the ≥80% thickness group, UCVA and BSCVA improved less than 1 lines, Kmax change was less than 0.5 D, and RC decreased less than 0.25 D. CONCLUSION: Implantation of KeraRing with mechanical tunnel creation in 40-80% of stromal thickness despite the variable insertion depth is effective.