Evolution in the use of intrastromal corneal ring segments for corneal ectasia

Purpose of review To report the recent advances in the use of intrastromal corneal ring segments (ICRS) for treating patients with corneal ectasia. Recent findings ICRS improve visual, refractive, and keratometric parameters in patients with keratoconus and postlaser in-situ keratomileusis ectasia. ICRS have been made safer, quicker, and more precise with the use of femtosecond lasers for ring insertion. ICRS produce better visual outcomes in patients with poor preoperative corrected distance visual acuity compared with patients with less preoperative visual impairment. Standard ICRS do not improve vision in patients with stage 3–4 keratoconus (Amsler–Krumeich classification), but newer models of ICRS, such as Intacs SK, appear promising for these patients. ICRS have been successfully combined with treatments such as corneal collagen cross-linking (CXL), penetrating keratoplasty, and photorefractive keratectomy. Summary ICRS variably improve visual acuity. Numerous questions concerning ICRS remain, including the duration of the effects of ICRS and the changes that ICRS induce on a biomechanical level. The optimal method for combined CXL and ICRS placement has not yet been determined. Further well-designed randomized controlled studies with long-term follow-up are needed for clarification.