Histopathological analysis of the corneal epithelium after contact lens wear.

Complications from contact lens wear are seldom examined histopathologically. Understanding of the epithelial reactions in response to contact lens wear would help early diagnosis and direct treatment action. Therefore, this study examines the histopathology of abrasion, epithelial edema, epithelial thinning and superficial punctate staining. Important factors in the etiology of these conditions are various definable lens and tear characteristics as well as mechanical effects from the lens. Observations on corneal innervation that have not been previously reported are used to help explain the reduced corneal sensitivity in the contact lens wearer. It is concluded that the breakdown of the epithelial surface prevents the epithelium from fulfilling its fluid and microorganism barrier functions. In addition, disturbance of the normal epithelial structure interferes with its ability to withstand further trauma and to convey the injury to the brain via the neural pathways.