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.