Intrastromal corneal ring segments in keratoconus: success and failure on a 10 year experience
First Author: M.Leitão PORTUGAL
Co Author(s): C. Rodrigues M. Marques F. Alves S. Alves H. Nogueira
Keratoconus is traditionally described as a progressive ectatic disorder of the cornea that usually begins in adolescence and affects the Corrected Distance Visual Acuity (CDVA) from mildly to a severe manner. The implantation of ICRS is a therapeutic option when the CDVA is significantly impaired or when there is a poor tolerance to contact lenses/spectacles. The purpose of this study is to evaluate the results of the implantation of Instrastromal Corneal Ring Segments (ICRS), namely CDVA, topographic changes, as well as complications.
This is a retrospective study involving 54 patients, a total of 70 eyes, diagnosed with stable keratoconus that underwent implantation of ICRS at our institution in the last 10 years and followed for 12-24 months.
Inclusion criteria included patients with a pre-op determination of stable keratoconus - changes in mean keratometry (mean K) less than 1D on the year prior to the implantation of ICRS. Exclusion criteria included other significant ophthalmic or systemic condition, previous ophthalmic surgery. The surgical procedures were performed using mechanical corneal dissection and inserted Intacs ICRS, following the manufacturer’s normogram. In the pre-op and post-op consultations (12 months and/or 24 months after surgery) there was an evaluation of the CDVA, refractions, slit lamp, corneal topographic analysis (using Ziemer’s Galilei G2) and possible complications.
In the pre-op evaluation, the mean CDVA was 0.49, with the second eye operated having a lower threshold for surgery (0.6). The mean K was 46.80, steep K 48.10, central corneal thickness (CCT) 488.5, thinnest corneal thickness (ThCT) 453.6, Inferior-Superior value (I-S) 10.22. In the two post-op evaluations at 6-12 months and 24 months, the mean values were, respectively, for CDVA 0.67 and 0.68, mean K 43.64 and 43.51, steep K 45.10 and 44.82, CCT 502.6 and 504.82, ThCT 447.74 and 459.52, and for I-S 8.82 and 8.54. In total there were three complications over the 2 year-period: two ICRS extrusions that required removal and one patient with recurrent keratitis.
According to our experience, the insertion of IRCS provides a valuable therapeutic option for patients with clinically significant keratoconus, as the CDVA and topographic measurements (above demonstrated) revealed significant improvement, providing great patient satisfaction and low rate of complications (0.056%) over this 2 year period.