Effects of Intracorneal Ring Segment on Corneal Biomechanics in Keratoconic Eyes

To evaluate the biomechanical changes of cornea after intracorneal ring segment (ICRS) implantation in keratoconic eyes 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). 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 1st month and 0.32±0.27 logMAR at the end of 3rd 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. 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.