Advancing Keratoconus Management: ECO-CAIRS, Biomechanics and the Evolution of Corneal Allogenic Intrastromal Ring Segments

orneal ectatic disorders, such as keratoconus, progressively impair visual acuity and visual quality by causing corneal thinning and irregular astigmatism.Intracorneal ring segments (ICRS) have been used to reshape the cornea and delay transplantation.However, synthetic polymethylmethacrylate ICRS present significant complications, including extrusion, corneal melt and neovascularization, due to their rigidity and non-physiological stress on the cornea.Corneal allogenic intrastromal ring segments (CAIRS), introduced in 2018, utilize donor corneal tissue to improve biocompatibility and integration while reducing extrusion risks.However, the inherent softness of CAIRS presents surgical challenges, prompting the development of femtosecond laser-assisted tunnel creation (femto-CAIRS) for improved precision.Air-drying techniques, such as the 'Jerky Technique', provided temporary rigidity but led to rehydration-related challenges during insertion of the ring segment.Extracorporeal cross-linking-optimized CAIRS (ECO-CAIRS) addresses these limitations by applying ultra-highfluence corneal cross-linking (30 and 60 J/cm² delivered as 30 mW/cm² continuous ultraviolet-A light) to stiffen the ring segments before implantation.This process shows several advantages.1.It facilitates surgical handling, because rigidity remains high even when the ring segment gets into contact with humidity.2. It temporarily reduces thickness, allowing for increased segment volume in the corneal stroma and potentially greater flattening effects.3. It eliminates all viable keratocytes, reducing the risk of transmitting keratocytes from another donor who might also have had keratoconus.In this article, we describe how we developed ECO-CAIRS.Preliminary clinical findings indicate that ECO-CAIRS simplifies insertion due to its greater stiffness and resistance to re-swelling during the ring insertion phase.As the technique evolves, ECO-CAIRS holds the potential to enhance keratoconus management by improving surgical efficiency while ensuring consistent and optimal visual rehabilitation outcomes.