Functional and biomechanical changes in keratoconic corneas after implantation of intracorneal ring segments 5 and 6mm in diameter

Abstract

AbstractPurpose To determinate biomechanical and functional changes in human keratoconic corneas after triangular section ring implantation in two designs.Methods Retrospective study of biomechanical properties of 46 patients (60 eyes) with keratoconus undergoing surgery Keraring® intracorneal ring segments divided into two groups according to 5 or 6 mm of diameter. Surgical technique to made the channel was with IntraLase femtosecond laser. UCVA and BSCVA were measured and biomechanical factors provided by the device ORA before surgery and postoperatively one month, 3 months and 6 months.Results After surgery, we obtained a significant increase (p<0.05) of the biomechanical parameters (CH and CRF) mean (0.87±2.59)mmHg for CH and (‐0.015±2.06)mmHg for CRF. This improvement is not homogeneous during the postoperative follow‐up in two groups in diameter. We found increased of CH top with rings of 6mm. The variations found in the CRF, are not significant at the descriptive level with any of the designs (p>0.05). At baseline‐ 6 months, the improvement in BSCVA (LogMAR) is 0.13 in 5mm diameter respect to 0.07 in 6mm in diameter. Among the changes in CH and BSCVA (LogMAR), there is a significant inverse correlation with 6mm rings at baseline‐ 1 month period (r=‐0.442) and 1 month‐ 3 month period 0.007 (r=‐0.511). No significant correlation was detected between CRF and BSCVA.Conclusion Intracorneal rings improve corneal biomechanics. The CH undergoes improvement in postoperative follow up with any of the ring designs, while the CRF is not affected significantly with any of the types. 5mm rings further improve best corrected visual acuity. This improvement is not related to changes in the biomechanical properties.