Cataracts produced in 4-week-old rats following exposure of the eye to various doses of 185 kVp X-rays, were analyzed 45 days after irradiation by scanning electron microscopy (SEM), as well as by conventional light microscopy (LM). The severity and extent of the ultrastructural damage seen at the LM and SEM levels varied as an increasing function of dose and correlated well with the clinical changes which were scored by slitlamp biomicroscopy prior to preparation. In the early-stage low-dose cataracts, damage was generally limited to the equatorial and posterior subcapsular regions. The late-stage high-dose cataracts were associated with clusters of 4 to 10 microns globules at the poles subcapsularly, massive disruption of the equatorial region and the formation of a granular matrix which extended to the posterior pole. Ultrastructural changes were also noted in the superficial cortical region, while the lenticular nucleus and the residium of the cortex remained unchanged.
