Role of the ocular surface in destructive corneal disease

Corneal destructive disease is related to the ocular surface in at least three ways. Firstly, the maintenance of surface integrity seems to protect the corneal stroma from ulceration. Such integrity is jeopardized if the corneal epithelial cells fail to replicate themselves, or if they fail to adhere tightly to the underlying stroma. Secondly, the ocular surface plays a role in ulceration. Elaboration of collagenolytic enzymes may occur in the abnormal ocular surface epithelial cells themselves. In addition, the surface may modulate the leucocytic response in the stroma, the leucocytes themselves being responsible for the ulceration of the stroma. Finally, the ocular surface appears to play a role in superficial vascularization of the cornea. When all of the corneal epithelium is lost, as is the case in widespread chemical injury, sluggish metabolic transformation of conjunctival cells is associated with vascularization.