THE DAMAGING EFFECT OF UV RAYS (WITH THE WAVELENGTH SHORTER THAN 320 NM) ON THE RABBIT ANTERIOR EYE SEGMENT .1. EARLY CHANGES AND THEIR PREVENTION BY CATALASE-APROTININ APPLICATION

In experiments carried out in rabbit eyes, UV rays of 254 or 312 nm wa velength damaged the anterior eye segment, whereas those of 365 nm wav elength did not. Two min irradiation with 254 nm UV rays led to a decr ease of catalase activity in the corneal epithelium. After 5 min irrad iation the catalase activity in the epithelium was not detectable at a ll. Catalase activity was also diminished in the corneal endothelium a nd lens epithelium. In this stage the changes were accompanied by decr eased activities of Na+-K+-dependent adenosine triphosphatase, gamma-g lutamyl transpeptidase and increased activities of lysosomal enzymes i n the corneal and lens epithelium as well as in the corneal endotheliu m. The transparency of the cornea and lens was decreased. Plasmin acti vity appeared in the tear fluid. The irradiation with UV rays of 312 n m caused similar disturbances, however, a longer exposure was necessar y. In contrast, irradiation with UV rays of 365 nm did not produce any changes. The described corneal disturbances were prevented by droppin g of catalase solution on the eye surface during the irradiation or sh ortly after it. However, after a protracted irradiation aprotinin had to be added to catalase to achieve the healing. The decrease of catala se activity and its prevention by a local application of catalase sugg ests a key role of oxyradicals in the damage of the eye by UV rays.