Epithelial Thickness Profile Change After Combined Topography-Guided Transepithelial Photorefractive Keratectomy and Corneal Cross-linking in Treatment of Keratoconus.

PURPOSE: To evaluate corneal epithelial remodeling after topography-guided transepithelial photorefractive keratectomy (PRK) combined with corneal collagen cross-linking (CXL) in the treatment of keratoconus.

METHODS: Retrospective analysis of the epithelial thickness distribution changes in 53 keratoconic eyes of 44 patients. Manifest refraction, maximum (Kmax) and minimum (Kmin) keratometry obtained by Placido topography, corneal irregularity index (IRI) measured by Scheimpflug topography, and the epithelial thickness profile over the central 5-mm zone obtained by anterior-segment spectral domain optical coherence tomography (SD-OCT) were evaluated preoperatively and at 1 to 3, 3 to 6, and more than 6 months postoperatively.

RESULTS: Preoperatively, the epithelial thickness at the thinnest area (MinArea) was 48.8 ± 4.4 µm, correlating negatively with Kmax (r = -0.310, P < .05) and IRI (r = -0.362, P < .05). At more than 6 months postoperatively, epithelial thickening of 5.5 ± 5.1 µm occurred at the thinnest area (MinArea). There was no significant change in the epithelial thickness in other areas, resulting in a decrease of difference in epithelial thickness between MinArea and the rest of the paracentral areas of 5.5 ± 4.3 µm. Corrected distance visual acuity, refractive astigmatism, Kmax, Kmin, and IRI all improved after the treatment (P < .05).

CONCLUSIONS: A significant epithelial thickness profile change occurred after the treatment due to an increase in thickness at the preoperatively thinnest area. Because the thickness in other areas remained largely unchanged, the treatment resulted in a more even epithelial thickness distribution. This may be attributed to regularized postoperative corneal stromal shape. [J Refract Surg. 2016;32(9):626-634.].