Size and Number of Epithelial Cells Washed from the Cornea after Contact Lens Wear

Using the technique of Fullard and Wilson, tear samples were collected atraumatically from the corneas of 14 rigid gas permeable (RGP) contact lens wearers, 14 soft contact lens (SCL) wearers, and 22 controls who did not wear contact lenses. Samples were analyzed for the number, size, and contiguity of the cellular contents. Both RGP and SCL groups had, on average, significantly fewer cells per sample than controls (median values were 11 and 12 cells vs. 44). The difference remained significant even after a correction of three cells was applied to account for cells adherent to the lenses. Approximately 80% of epithelial cells from both lens wear and control eyes were found in isolation, whereas 20% were contiguous with 1 or 2 other cells. This result is compatible with the majority of epithelial cells having exfoliated from the surface of the cornea after detaching from their neighbors, rather than detaching in sheets of cells. The cell length and cell area were analyzed. RGP wearers had significantly smaller cells than controls, whereas SCL wearers had slightly (but significantly) larger cells. These results may reflect changes in the exfoliation mechanism of the corneal epithelium in contact lens wear.