Complete 360-Degree Intrastromal Corneal Rings With and Without Corneal Cross-Linking in the Management of Keratoconus Publisher



Khorraminejad M¹ ; Mohammadpour M² ; Abulhosein R³ Show Affiliations
Source: Keratoconus: Optical and Surgical Management Published:2024

Abstract

An effective therapeutic option for individuals with keratoconus (KCN) is the intrastromal corneal ring (ICR), a type of implant that is either segmental arc-shaped or 360-degree annular-shaped. 1, 2 ICRs were initially designed by Barraquer (1949) to correct myopia. The surgical principle was based on placing a complete biocompatible rigid ring, centered on the pupil, between the corneal lamellae through the opening of a superficial flap previously cut with a microkeratome. 3, 4 This approach allowed flattening of the center of the cornea. 5 However, the early results were not conclusive because of the cutting of the flap. It was the work of Fleming and Reynolds (1987) that produced the first promising results. 6 They were the first to envisage the introduction of a segmental ring into a preformed tunnel with the help of metal guides, allowing the stabilization of the device while completely sparing the optical axis. Thus, they benefited from a so-called “additive” approach, sparing the corneal tissue, limiting the risks of reduced vision, and making it reversible. This technique was applied by different commercial companies, such as KeravisionTM and then Addition TechnologieTM for Intacs® type ICR and MediphacosTM for Ferrararing® or Keraring® type of ICR. However, the advent of the excimer laser and LASIK procedure in the 1990s greatly inhibited the growth of ICRs in the refractive surgery market. The problem was the poor predictability of the correction obtained with ICR, which depended on numerous parameters that were difficult to control for a refractive outcome as accurate as half a diopter. However, laser photo-ablation offered considerably greater refractive precision. It was not until 1997 that Fleming and Colin were the first to propose using ICR for managing corneal ectasia in patients with KCN. 7 Secondly, the first case of ICR implantation for treating one of the first post-LASIK ectasias was described by Lovisolo et al. (1999).8 © 2025 selection and editorial matter, Mehrdad Mohammadpour and Masoud Khorrami-Nejad; individual chapters, the contributors.