The role of the polymorphonuclear leukocyte in the induction of corneal edema

Corneal inflammation is frequently associated with the development of corneal edema. It has been suggested the development of corneal edema might in some way be related to the presence of polymorphonuclear leukocytes (PMNLs) within inflamed corneas. In the present studies, it was found that corneal thickness markedly increased after experimental infection with Pseudomonas aeruginosa, but in guinea pigs made neutropenic by whole body irradiation, significantly less of an increase in corneal thickness occurred. Furthermore, corneas from non-neutropenic animals experimentally infected with P. aeruginosa consistently showed a greater increase in water content than did infected corneas from neutropenic animals. Over the first 48 hr of infection, the increase in corneal water was directly proportional to the corneal ingress of radiolabelled PMNLs. Corneal inflammation induced by intracorneal injection of the PMNL chemotactic agents phorbol myristate acetate (PMA) or endotoxin was also associated with a significant increase in corneal water compared with neutropenic animals. These data strongly suggest that activated PMNLs in the cornea are responsible for the induction of corneal edema in infected corneas.