Evaluation of Keratoconus Correction by Ferrara Intracorneal Ring Segments

  Background and Objective: Evaluation of the results, safety, and stability of ferrara intracorneal ring segment (FICRS) implantation for Keratoconus correction (age range was 24.39±8.32 years).   Materials and Methods: In this clinical trial study, 64 eyes of 57 patients with keratoconus and clear cornea that had FICRS implantation were studied. Uncorrected visual acuity (UCVA), best-spectacle corrected visual acuity (BSCVA), refractive errors, and corneal data from Orb scan II, and complications were analyzed.   Results: The follow-up was 18 months ± 6.45 (SD), the UCVA improved from 1.14 logarithm of the minimum angle of resolution (Log MAR) ± 0.53 (SD) to 0.48 og MAR ± 0.44 (SD) (P≤ 0.001) and the BSCVA improved from 0.44 Log MAR ± 0.40 (SD) to 0.23 Log MAR ± 0.19 (SD) (P≤ 0.001). Improvement of main outcome measures were as follows: 4.90 diopter (D) ± 3.33 (SD) for Spherical equivalent (P≤ 0.001), 4.16 D ±3.24 (SD) for Spherical refractive error (P≤ 0.001), 1.49±2.31 (SD) for cylindrical refractive error (P≤ 0.001). Corneal topography showed more improvement of corneal uniformity and irregular astigmatism. Minimum and maximum central corneal powers decreased 1.75 D±5.94 (SD) (P≤ 0.03) and 4.75 D±3.33 (SD) (P≤ 0.001), respectively. Significant decrease in anterior corneal curvature and posterior best-fit sphere curvature were observed. Segment extrusion one eye (16%), superficial position 1 eye (1.6%), and infectin in 5 eyes (7.8%) had occurred.   Conclusion: During 18 months, FICRS implantation improved both UCVA and BSCVA, however, it reduced corneal steepening and astigmatism. Whereas, increased topographic regularity. FICRS implantation was a safe procedure that had led to stable results. This procedure prevented or delayed corneal graft in many cases.