Chapter 23 - Intrastromal Corneal Ring Segments Mechanism and Techniques

Abstract

Intrastromal corneal ring segments (ICRSs) are implanted to regularize the cornea in keratoconus. The mechanism of action is based on the idea of the addition of material to the corneal periphery to flatten the corneal center (thickness law). ICRSs act as a spacer and shorten the arc length of the cornea. The corrective effect is correlated in direct proportion to the thickness of the implant and in inverse proportion to its diameter (optical zone). To implant ICRSs into the corneal stroma, two techniques can be applied: the manual (mechanical) technique and the femtosecond laser technique. Although the first technique used for ICRS implantation was the manual technique, femtosecond laser technique is the preferred technique because it has very good visual and refractive results and much lower complication rates. Femtosecond laser technique for ICRS implantation is fast, safe, and easy, even for an inexperienced surgeon.