Effect of cortisone on vascularization and opacification of the cornea induced by alloxan.

THERE are few reports in the literature of experimental work dealing with the effect of cortisone upon corneal vascularization, and the evidence so fair advanced is partly conflicting (Duke-Elder and Ashton, 1951), but there is already some indication from clinical observers that cortisone exerts a considerable inhibitory influence on the formation of ne\v vessels in the diseased cornea. The experimental vwork reported in this paper investigates this subject further by the use ot a recently evolved technique which has particular advantages for this study. Before proceeding to investigate the effect of cortisone upon corneal vascularization it is necessary to consider the possible stimuli which might initiate new vessel formation; although the causes are still quite unknown, many theories have been advanced, some of which have an especial bearing upon the experimental conditions. Thus assuming for the moment that new vessel formation arises in response to a chemical substance liberated in traumatized tissue, as suggested by Michaelson and Campbell (1949). any effect of cortisone may be due to a neutralizing mechanism, and the extent of its action Would then depend upon the, size of the lesion and the quantity of cortisone administered. Similarly, the severity of the lesion would be of importance were vascularization to result from alterations in the normal tissue tension, as suggested by Cogan (1949). In attempting, therefore, to assess the effect of a given dose of cortisone upon corneal vascularization, it is essential that the experimental lesion should be, as far as variation in individual animals will allow, both standardized, in order to permit comparison, and the minimal required to produce vascularization, to ensure adequate sensitivity. Although the work already published on this subject is of great importance in assessing the probable therapeutic value of cortisone, it cannot be held that caustic (Jones and Meyer, 1950; Leopold and others, 1951), or thermal burns (Lister and Greaves, 1951), are entirely satisfactory methods for investigating this problem, for the