Photosensitization of the Eye with Methoxsalen

Abstract

Introduction In the first part of this study¹ it was shown that guinea pig eyes can be sensitized to an otherwise harmless kind of energy, long ultraviolet light, with a photosensitizing substance, methoxsalen.* (Since publication of the first paper, additional evidence has been presented that the action spectrum of methoxsalen peaks in the long ultraviolet range.)^2,3 In the first study guinea pigs were exposed to long ultraviolet light continuously for 24 hours. Half of them, the test animals, received methoxsalen intraperitoneally one hour prior to exposure. The harmless nature of long ultraviolet was demonstrated by the controls, none of which sustained ocular injury. The photosensitizing effect of methoxsalen was demonstrated by the test animals, none of which escaped ocular injury. The damage produced was acute and severe. The purpose of the current study was to determine whether a chronic effect could be produced by the daily administration of