A morphological description of human cataractous lenses by SEM

Lens epithelial cell density and histomorphological study in cataractous lenses

Human epithelial cell density was determined from flat preparation of 195 cataractous lenses from 108 males and 87 females between 30 and 80 years of age. The mature cataracts had significantly lower cell counts than the other cataracts. Cell density was significantly higher in the females than in the males. Morphohistological study of the epithelia was focused on the following cataract types: (1) nuclear, (2) posterior subcapsular, (3) mature, (4) mixed, (5) hypermature, and (6) black. The major cataractous changes in all types involved vacuolization of the cytoplasm. The mature types of cataractous epithelia showed 56% superimposed cells; the epithelia in nuclear, posterior subcapsular, and black cataracts showed between 6% and 16%. In the hypermature cataracts, four of five tissues analyzed showed superimposed cells. The superimposed areas are probably the source of increased and altered cell activity. We propose that the metaplastic processes leading to posterior capsular opacification originate from these areas. The majority of nuclear and black cataracts were almost similar to the normal human lens epithelium with more or less uniform distribution of cells. Nucleus shrinkage (5 microns) was more evident in nuclear cataracts; in subcapsular cataracts most of the nuclei were large (average 9 microns diameter). Variation in morphological changes like vacuolization of cytoplasm and nuclei, pyknotic nuclei, and superimposed cells was more evident in the mixed type of cataracts.

Scanning EM studies of normal human lens fibres and fibres from nuclear cataracts

Normal human lenses obtained from an eye bank, and the central nuclear regions from nuclear sclerotic cataracts, were examined using scanning electron microscopy. Lens fibres were found to possess a varied array of well defined interlocking processes. Fibres from brunescent nuclear cataracts showed complete preservation of membrane architecture in contrast to the extensive membrane disruption that has been seen in cortical cataracts.

Secondary cataract material collected with a glass cannula. A SEM study

Secondary cataract material from three patients, collected with a glass cannula approx. 18, 24 and 30 months respectively after operation, was prepared for SEM examination. For the soft samples this was done by filtration through a millipore filter followed by fixation and drying. The more solid material was suspended in a fixation solution, followed by centrifuging, suspension in 70% ethanol and drying on a specimen-holder. The short residence samples (18 months) showed mainly erythrocytes, some (inflammatory) cells and degenerated lens-fibre material. Most of the more solid material, which was collected more than 20 months after operation, showed fragments of (regenerated) capsule epithelium and pieces of solid lens-fibre material with fragments of capsule epithelium attached.

Soemmering's ring, an aspect of secondary cataract: a morphological description by SEM

A Soemmering's ring attached to a patient's I.O.L. was removed and processed for SEM-examination. The enveloping structure of the Soemmering's ring was clearly of capsular origin, adherent along a single line and forming an envelope around the inner material. The envelope had a membranous character. The contents of the ring varied from the outside to the centre. Close to the capsule envelope a more or less amorphous material was found. Most of the contents of the ring was made up of lens-fibre material. Sometimes clear lens fibres were visible with densely packed lens-fibre proteins, sometimes with clusters of recrystallized proteins, rod-shaped or spherical, surrounded by what appeared to be amorphous material. The recrystallized and the amorphous lens-fibre material are similar to material found in cataractous lenses.