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.