EXPERIMENTALLY-INDUCED STEROID CATARACT IN THE RAT - A SCANNING ELECTRON-MICROSCOPIC STUDY

To clarify the histopathological changes of experimentally induced ste roid cataract in Brown-Norway rat eyes, a scanning electron microscopi c study was performed. The biomicroscopic appearance of the cataracts, which was quite similar to that of human eyes, was induced by daily a pplication, either topically or systemically, of prednisolone acetate for 12 months. A single dose of 2 Gy X ray was given to the light eyes of all the animals 2 weeks before drug administration. Twenty-seven r ats were divided into three groups: a control group (CTL), a group rec eiving topically administered prednisolone (TOP), and a group receivin g systemically administered prednisolone (SYS). In vivo observation wa s performed through a slit-lamp microscope, and the lens findings were documented and objectively analyzed by an anterior eye segment analys is system over a period of 12 months. At the end of the 12-month perio d, X-ray-irradiated light eyes in the CTL group showed some minor lens chang es on biomicroscopy, and non-X-ray-irradiated left eyes were al most normal. In the TOP and SYS groups, either with or without X-ray i rradiation, lenses showed anterior and posterior subcapsular opacifica tion; however, the gr ade and increase of lens opacification were high er and faster in the eyes with X-ray irradiation. Scanning electron mi croscopic findings of the three groups at the 12th month were as follo ws. In the CTL group, the X-ray-irradiated right eyes showed minor cha nges. In the TOP group, the X-ray-irradiated light eyes showed marked damage in the lens fibers of the anterior and posterior cortices, whil e the nonirradiated left eyes showed minor changes. In the SYS group, the X-ray-irradiated right eyes showed prominent cataractous disorgani zation of lens fibers in the shallow anterior and posterior cortices, and the non-X-ray-irradiated lenses were almost the same as those in t he TOP group. These findings might suggest that even a minimum invasio n of a low dose of X-ray irradiation plays a cocataractogenic or synca taractogenic role during the formation of steroid cataracts. (C) 1997 by Elsevier Science, Inc. All rights reserved.