Confocal biomicroscopic changes of the corneal layers following femtosecond laser-assisted MyoRing implantation in keratoconus

Purpose: To evaluate the effect of the femtosecond laser-assisted MyoRing implantation on the confocal biomicroscopic findings in different corneal layers of the patients with keratoconus. Methods: Twelve eyes of 12 patients with mild to moderate keratoconus (keratometry between 48 and 52 diopters) and intolerance to hard contact lens entered the study. All the included patients underwent femtosecond laser-assisted MyoRing (Dioptex GmBH, Linz, Austria) implantation. The confocal biomicroscopy of the cornea was performed for all corneal layers in the center and periphery preoperatively and 3 and 6 months postoperatively. The cell counts and the qualitative findings in each layer of the cornea were compared between preoperative and 3 and 6 months postoperative images. Results: Compared with preoperative values, the central epithelial and the central and peripheral midstromal cell counts were significantly decreased 6 months after MyoRing implantation (P ¼ 0.015, P ¼ 0.010 and 0.005, respectively). Furthermore, compared with preoperative values, the peripheral posterior stromal cell count was significantly decreased 3 months after MyoRing implantation (P ¼ 0.033). In the qualitative analysis, highly reflective nuclei in the basal epithelium, transient disruption in the subepithelial nerve plexus, increase in the reflectivity of the stromal keratocyte, and normal endothelial cell morphology were seen. Conclusions: Our study demonstrated some findings similar to that reported in intrastromal corneal ring segments (ICRS): decreased central epithelial cell counts, highly reflective nuclei in the basal epithelium, transient disruption in the subepithelial nerve plexus, and normal endothelial cell count and morphology. In addition, a decrease in the central and peripheral midstromal, transient decrease in posterior stromal cell counts, and absence of amorphous depositions were in contrast with the findings reported in ICRS.