In the course of healing of experimental ulcer one could observe a distinct difference between a cornea, subjected to the action of glycerol and a control one. The damage to the chemical structure of collagenous fibers was much smaller than in the control. On the basis of the investigations performed one may conclude that glycerol, through dehydration of the corneal tissue and stimulation of mucopolysaccharide synthesis, suppresses the activity of collagenase. In polarized light this process was manifested by the double refraction phenomenon and in clinical observation--by an accelerated healing of ulcer.