Intrastromal Strengthening of the Cornea by Technology BLOK in Case of Ectasia after LASIK with Limited Thickness and Inefficiency of Cross-Linking (Clinical Observation)

Abstract

Iatrogenic keratectasia is a corneal disease caused by refractive surgery, most frequently after laser in situ keratomileusis (LASIK) as a surgical correction of ametropia, and also after injuries, penetrating and lamellar keratoplasty. The following changes are noted in case of keratectasia after laser keratomileusis: an increase in keratometric indices in the central and lower parts of the cornea, a decrease in stromal thickness and a myopic shift in refraction, a progressive impairment of visual functions — a decrease in uncorrected visual acuity, monocular diplopia and an inability of spherocylindrical correction. A thin corneal bed or small residual stromal thickness, re-surgery LASIK in anamnesis, and also the initial preoperative features of the corneal topogram (Irregularity, asymmetric bow tie pattern) are considered to be the main risk factors of keratectasia after LASIK surgery.Methods. A patient with secondary keratectasia who had previously undergone LASIK and crosslinking was found to have progressive secondary keratectasia and decreased visual functions. An individual allograft was implanted (the form of a Landolt ring, 300 µm, at a depth of 290 µm) using the technology of bandage keratoplasty. Cutting transportat graft and tunnels for implantation were produced with the help of femtosecond laser. The data of visometry and keratotopography were evaluated.Results. As a result of the formation of the bandage, the functions of the eyes improved, and ectasia did not progress for 6 months. Visual acuity increased from 0.15 to 0.66, the average value of keratometry was 40.35 diopters, with the initial 44.8 diopters. The minimal corneal thickness remained at 440 µm.Conclusion. The proposed surgical technology BLOK allows to get an effective result in case of keratectasia after LASIK, which is manifested in improving visual functions, strengthening the cornea and normalizing its surface, as well as provides reduction of the further progression of keratectasia.