Occurs when fluorescein penetrates damaged cell membranes or when it fills gaps in the epithelial cell surface. Gaps are created when cells are damaged or displaced. There are a large number of reasons for corneal staining caused by lens wear including hypoxia, deposits, care products, lens fit, lens surface or edge irregularities, foreign bodies, and tear film disruption.
The integrity of the epithelium should be assessed carefully at each contact lens aftercare visit. Attention should be paid to the extent, depth and type of staining. Corneal staining of grade 2 or more in any area of the cornea is considered unacceptable.
