SEM examination on corneal epithelial cells at different time points after exposure (A) At post-exposure 1 hour, no obvious superficial epithelial sloughing, or increased intercellular gaps was found. (B) At post-exposure 2 hours, the increased intercellular gaps can be clearly seen. However, no obvious epithelial sloughing can be detected. (C) At post-exposure 4 hours, sloughing of superficial epithelial cells were observed.

<p>Black thin arrow: intercellular borders. White arrows: the increased intercellular borders with mild detachment of the epithelial cells from underlying layers. Black thick arrows: Sloughing of the superficial epithelial cells from the underlying layers. Bar: 50 um”