METHODS: This prospective comparative observational study included 20 patients(20 eyes)who underwent PK as study group and 16 patients(16 eyes)as control group. Corneal epithelial thickness mapping using AS-OCT was performed at 2wk, 1 and 3mo postoperatively. The parameters of epithelial thickness and distribution at the 3mo were compared to 16 patients(16 eyes)with allograft rejection following PK.

RESULTS: There was significant decline in the superior, inferior, maximum, and minimum epithelial thickness values of the study group at 1mo compared to 2wk(P=0.0004, 0.0001, 0.0001, 0.04 respectively)with no significant differences at 3mo compared to 1mo(P=0.4, 0.1, 0.8)respectively. Percentage of reduction in epithelial thickness was significantly higher than that of stromal thickness at 1mo compared to 2wk(P=0.04). The epithelial thickness maps showed a similar pattern of epithelial thickness distribution in the study group and in the rejection group showing considerable corneal edema. However, the allograft rejection group showed irregular pattern of epithelial thickness distribution in patients showing relatively higher central corneal thickness(CCT)as measured by pachymetry map.

CONCLUSION: Quantitative assessment of graft epithelial remodeling following PK shows early changes that contribute to significant corneal graft thickness changes. Changes in corneal epithelial thickness and pattern of distribution could be used as an indicator for corneal graft rejection.