Human senile cataract. Light- and electron-microscopic studies of the morphology of the anterior lens structures, with special reference of anterior capsular/subcapsular opacity.

Light- and electron-microscopic studies of human senile cataractous lenses with and without biomicroscopically detectable anterior capsular/subcapsular opacity (ACSCO) revealed the main difference between the two types of cataract to be in the subepithelial cortex, where ACSCO lenses showed disintegrating cortex fibres, fibres of the deep cortical type and even in some cases collapsed fibres. These findings were considered to be associated with the decomposition and disappearance of the superficial cortex in ACSCO lenses. Numerous mitochondria in the epithelium of ACSCO lenses point towards a high oxidative metabolism, which may facilitate active transport across the epithelium. No difference in capsular surface morphology between cataractous lenses with and without ACSCO was found by scanning electron microscopy. Transmission electron microscopy showed in both categories of lenses granular inclusions in the capsules, most pronounced in totally opaque lenses. Large intercellular vacuoles were seen in the anterior part of the epithelium, both light- and electron-microscopically in both categories. Consequently, these ultrastructural changes do not seem to form part of the biomicroscopical picture of ACSCO. Based on our study, we prefer the term: ASCO (anterior subcapsular opacity) in place of ACSCO, the latter term having been used by us previously.