Corneal Epithelial Thickness Mapping And Refractive Outcome After Transepithelial Photorefractive Keratectomy For Myopia - An East Asian Population-Based Study

The purpose of the study was to analyze the corneal epithelial thickness mapping changes after transepithelial photorefractive keratectomy for myopic patients and its effects on post-operative refraction.

Kaohsiung Veterans General Hospital, Kaohsiung

We retrospectively examined 40 eyes of 20 patients who underwent transepithelial photorefractive keratectomy for myopic correction. Spheroequivalent refraction ranged from -1.0 to -10.0 diopters (D). Corneal epithelial thickness maps and associated data were obtained by anterior segment optical coherence tomography pre-operatively along with standard ophthalmic examination. Follow-up was up to 6 months postoperatively. Epithelial thickness maps included a central zone and eight peripheral zones. Correlations between postoperative epithelial thickness changes and the post-operative refraction, amount of correction, planned optical zone, ablation depth, residual stromal thickness and pre-operative epithelial thickness were analyzed.

Decrease in corneal epithelial thickness was seen across all zones 2 months after photorefractive surgery. The corneal epithelium thickness (53.86 ± 3.34 µm) at the central zone reached its pre-operative status at 4 months, and continued to growth thicker at 6 months, with an average of 63.44 ± 4.82 µm. At 4 months postoperatively, the average refraction was -0.86 ± 0.23 diopters, and at 6 months postoperatively, the average refraction was -0.46 ± 0.16 diopters.

The corneal epithelial thickness increased during the first 4 months after transepithelial photorefractive keratectomy. The increase continued up until 6 months postoperatively, but a slowdown was observed. Myopic regression observed during the study period was associated with the refractive effects of epithelial remodelling.