Effects of Intracorneal Ring Segment on Corneal Biomechanics in Keratoconic Eyes

Purpose: To evaluate the biomechanical changes of cornea after intracorneal ring segment (ICRS) implantation in keratoconic eyes. Methods: In this study, 1 or 2 ICRS were inserted in 17 keratoconic eyes. Best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), refraction, and keratometry were evaluated preoperatively and 1 and 3 months after surgery. Corneal hysteresis (CH) and corneal resistance factor (CRF) were also measured preoperatively and postoperatively with ocular response analyzer (ORA). Results: ICRS was inserted in 17 keratoconic eyes (12 patients). Mean UCVA significantly increased from 0.72 +/- 0.37 logMAR to 0.54 +/- 0.27 logMAR (P=0.027) and 0.46 +/- 0.30 logMAR (P=0.01) 1 and 3 months after surgery, respectively. Mean BSCVA increased from 0.41 +/- 0.29 logMAR to 0.32 +/- 0.26 logMAR at the end of the 1(st) month and 0.32 +/- 0.27 logMAR at the end of 3(rd) month postoperatively. These changes were not significant. Spherical equivalent (SE) significantly decreased from -5.64 +/- 3.21 Diopter (D) to -3.36 +/- 2.74 D (P=0.009) 1 month and -3.51 +/- 2.04 D (P=0.002) at the 3 months after surgery. Mean keratometry also significantly decreased from 49.82 +/- 4.33 D to 48.10 +/- 3.64 D (P=0.010) and 47.40 +/- 3.47 D (P=0.003) at 1- and 3- month follow-ups, respectively. Mean CH was 7.48 +/- 1.65 mmHg and mean CRF was 5.98 +/- 2.06 mmHg, preoperatively. At 1-month follow-up, their values were 7.13 +/- 1.56 mmHg and 5.74 +/- 1.60 mmHg, respectively. At 3-month follow-up, their values were 7.20 +/- 1.23 mmHg and 5.80 +/- 1.72 mmHg, respectively. The CH and CRF changes at 1- and 3-month follow-ups were not significant. Conclusion: After ICRS insertion in keratoconic eyes, no significant changes were observed in mean values measured with the ORA at 1- and 3-month follow-ups.