Possibilities of Intralamellar Keratoplasty in Rehabilitation of Keratoconus Patients

Keratoconus is one of the topical problems in modern ophthalmology. Among the currently used treatment methods is intralamellar keratoplasty that utilizes allomaterials or homotransplants. The surgery technique has obvious advantages over penetrating and deep anterior lamellar keratoplasty. There is no risk of tissue incompatibility, the recovery period is shorter, and prolonged use of corticosteroids is not necessary. In recent years, technological development has made the application of femtosecond laser a standard procedure for various surgical interventions on the cornea, particularly for creation of intrastromal tunnels and corneal bags. This article presents an analysis of the modern literature data about different intralamellar keratoplasty techniques for treatment of keratoconus. The described techniques show its great clinical possibilities, especially the intrastromal keratoplasty variant with implantation of biological tissues. One of such techniques was developed and tried by a group of specialists at Research Institute of Eye Diseases in 2014. It involves recovery of corneal thickness in the ectatic area by intralamellar transplantation of a layered transplant of adequate size, which acts as a bandage. The surgery simultaneously affects the stabilization action, corrects refractive errors and eliminates the structural changes; it was accordingly named bandage therapeutic-optical keratoplasty (BTOK). The indication for its usage is progressing keratoconus in stage II–III patients. Among the described outcomes are cease of the disease progression in long-term follow-up, improvement of corrected and uncorrected visual acuity. The foreign analogue of the technique is Corneal Allogenic Intrastromal Ring Segments (CAIRS) by Jacob S. et al. His study included 20 patients with stages I to IV keratoconus; all patients undergone corneal cross-linking as the first stage, then they had CAIRS implanted into the intrastromal tunnels prepared with femtosecond laser. In both methods, the authors point at the improvement of corrected and uncorrected visual acuity. None of the patients had implant dislocation or keratoconus progression during the follow-up period