ABSTRACT.Purpose: To compare values of the human lens autofluorescence and back light scatter measurements with the improved Lens Opacities Classification System, LOCS III. Methods: We measured autofluorescence and back light scatter of the lens from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The retroillumination and slit-lamp photographs of the lenses were graded according to LOCS III by the Center for Ophthalmic Research in Boston. Lens fluorometry was carried out with a previously described technique using bluegreen (495 nm/520 nm) autofluorescence range. Interzeag Lens Opacity Meter 701 was used for light scatter measurements. Results: LOCS III nuclear opalescence and color grades were statistically significantly correlated with lens autofluorescence as well as with light scatter values. The lens transmission index of autofluorescence measurements showed the highest correlation with the nuclear color (rΩª0.71; p∞0.0001) and the light scatter value with nuclear opalescence (rΩ0.64; p∞0.0001). There was no correlation between autofluorescence measurements and LOCS III grades of cortical or posterior subcapsular cataract. A weak relation could be found between the grades of cortical cataract and light scatter values. Conclusions:The lens fluorometry provides a practical clinical technique to evaluate the yellow coloration and opalescence of the human lens nucleus. It may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.

Morphological changes are seen in young rat lens, following incubation in isotonic TC-199 medium containing glucose concentrations ranging from 0 to 12 mM. A thin superficial opacity of anterior and posterior lens develops after 20 h in 0 mM glucose medium. After 48 h a nuclear cataract is found, separated from the thicker superficial opacity by clear cortex. Epithelial cell nuclei become pyknotic and superficial cortical fibers swell until cell membranes appear to rupture and fibers coalesce to form large balloon-shaped structures. Only remnants of the characteristic cytoplasmic projections on the cortical cell surfaces remain, and the degree of lens fiber cell swelling is not uniform along its length but appears to be localized. The deeper cortical fibers appear unaffected and resemble normal fibers. This experimental cataract shows striking similarities to the biomicroscopic appearance of the ‘hypoglycemic’ cataract in the human.

Although the quantity of insoluble lens proteins increases with aging and cataracts, it is unknown whether the quality, such as protein structure, also changes correspondingly. In this study front surface fluorometry was used to study powdered samples of insoluble proteins isolated from young calf and old cow lenses, as well as from young clear and old cataractous human lenses. Tryptophan (Trp) fluorescence shows that there is a difference in protein conformation between young and old bovine samples. The old sample appears to have more open structure. This is demonstrated by a red shift in Trp emission maxima. The water-insoluble fraction shows 3-4 nm shift, while its urea-soluble and urea-insoluble fraction show 1-2 nm shift. The unfoldedness found in soluble crystallins is thus retained when they become insoluble. Both young and old human insoluble samples give a long Trp emission wavelength without showing any difference. Another major change that can be measured by fluorescence is the appearance of the 370/440 nm peak in old bovine insoluble powdered samples. Human samples also give this peak, and its position shifts to a longer wavelength in senile lenses.

Two sets of lens photogradings were used to investigate the effect of cataract type and severity on the intra- and interob-server agreement between two graders using the Lens Opacities Classification System III (LOCS III). The first set consisted of 193 eyes, largely of mild-to-moderate opacities for all cataract types. The second set consisted of a similar number of cataracts in each group subdivided into mild, moderate, and severe, a total of 159 lens photographs. Intraclass correlation coefficient (r₁) was used to measure the intra- and interobserver reproducibility and 95% tolerance limit the intra- and interobserver variability. Results showed that more variability was seen in intra- and interobserver agreement when grading increasing posterior subcapsular opacities. Decreased reproducibility and increased variability in interobserver agreement were seen in increasing cortical gradings, and decreased reproducibility in interobserver agreement in more severe nuclear opacities. No difference was seen in nuclear color gradings. The results suggest that the effect of cataract severity on interobserver agreement should be taken into consideration in longitudinal studies requiring several photograders.