Evaluation of intrastromal corneal ring segments for treatment of keratoconus with a mechanical implantation technique
Purpose: To evaluate the clinical outcomes of intrastromal corneal ring segment (ICRS) implantation in patients with keratoconus using a mechanical implantation technique. Materials and Methods: Thirty eyes of 17 patients with keratoconus were enrolled. ICRSs (Keraring) were implanted after dissection of the tunnel using Tunc's specially designed dissector under suction. A complete ophthalmic examination was performed, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent, keratometric readings, inferosuperior asymmetry index (ISAI), and ultrasound pachymetry. All 3-, 6-, and 12-month follow-ups were completed, and statistical analysis was performed. Results: The mean preoperative UDVA for all eyes was 1.36 +/- 0.64 logMAR. At 12 months, the mean UDVA was 0.51 +/- 0.28 logMAR (P = 0.001), and the mean preoperative CDVA was 0.57 +/- 0.29 logMAR, which improved to 0.23 +/- 0.18 (P = 0.001) at 1 year. There was a significant reduction in spherical equivalent refractive error from -6.42 +/- 4.69 diopters (D) preoperatively to -1.26 +/- 1.45 D (P = 0.001) at 1 year. In the same period, the mean K-readings improved from 49.38 +/- 3.72 D to 44.43 +/- 3.13 D (P = 0.001), and the mean ISAI improved from 7.92 +/- 3.12 to 4.21 +/- 1.96 (P = 0.003). No significant changes in mean central corneal thickness were observed postoperatively. There were no major complications during and or after surgery. Conclusion: ICRS implantation using a unique mechanical dissection technique is a safe and effective treatment for keratoconus. All parameters improved by the 1-year follow-up.