FACTORS AFFECTING THE HYDRATION OF THE CORNEA IN THE EXCISED EYE AND THE LIVING ANIMAL

Abstract

RECENTLY, the influence of metabolism on the water content of the excised cornea has been studied by several investigators. Schwartz, Danes, and Leinfelder (1954) immersed pieces of excised corneae in a nutrient medium and modified the metabolism by cold, lack of substrates, and the use of metabolic inhibitors. From their studies, they concluded that the mechanism regulating corneal hydration was dependent on energy derived from the aerobic and anaerobic metabolism of glucose. It was observed that the corneae of eyes left for 24 hrs in a cold moist chamber increased in water content and decreased again on warming to 31C., and that anoxia caused a marked increase in hydration. He concluded that his experimental results were consistent with the existence of an active transport mechanism. in the cornea. Similar con- clusions to those reached by these workers were reported by Langham (1955a, b) from studies of the effect of aerobic and anaerobic metabolism on corneal thickness and of the movement of sodium and water into the cornea of the excised eye immediately after enucleation. Certain of the dyes and inhibitors led to an increased hydration but inhibitors of cholinesterase were without effect. The observation that iodoacetic acid increased corneal hydration when glycolysis was inhibited by over half led Philpot to conclude that glycolysis was necessary to the mainten- ance of corneal hydration. No attempt, however, was made in Philpot's study to ascertain if the action of these compounds on corneal hydration was due to an inhibition of the metabolic processes regulating corneal hydration or to a non-specific action on the permeability of the cornea to water and salt. This consideration is especially important in view of the observations of Herrmann and Hickman (1948) that iodoacetic acid in low concentrations reduced the cohesion of the epithelium to the underlying stroma.