Lens autofluorescence and light scatter in relation to the lens opacities classification system, LOCS III.

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 blue-green (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 (r = -0.71; p < 0.0001) and the light scatter value with nuclear opalescence (r = 0.64; 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.

Influence of lens autofluorescence on retinal nerve fiber layer evaluation.

BACKGROUND: Yellow-brown coloration of the human lens increases with age and is associated with increasing lens autofluorescence. This may interfere with retinal image through scatter and absorption. PATIENTS AND METHODS: We measured the lens autofluorescence (AF) of 30 eyes of 30 healthy subjects and evaluated their retinal nerve fiber layer (RNFL) visibility from fundus photographs. These otherwise healthy eyes showed a varying degree of yellow-brown coloration of the lens. Lens fluorometry was carried out with a previously described technique using blue-green AF range (495 nm/520 nm). RNFL photographs were taken with a Canon CF-60 ZA wide angle camera with blue (495 nm) interference filter and low-sensitivity, high resolution black-and-white film. RESULTS AND CONCLUSION: Lens yellowing expressed here by means of lens autofluorescence measurements, was statistically significantly (r = -0.53, p = 0.0008) correlated with the RNFL visibility score. In stepwise regression analysis adding age to the model including only the maximum AF did not reduce the residual standard deviation statistically significantly (p = 0.1). This suggests that lens yellowing has an effect on RNFL visibility and may be an important confounding factor in clinical RNFL evaluation.

Autofluorescence in cataractous human lens and its relationship to light scatter.

The autofluorescence profile of the lens was measured from 84 eyes of 84 patients with cortical, nuclear, posterior subcapsular, or mixed lens opacities. Measurements were performed with a fluorometer in the blue-green autofluorescence range (495 nm/520 nm). The mean maximum autofluorescence value differed in every cataract group statistically significantly from that of the age matched controls (p < or = 0.0058). The highest autofluorescence values were measured in nuclear and mixed cataract groups (p < 0.0001) with high and narrow autofluorescence profile. In cortical cataracts the curve was low and flattened and the mean maximum autofluorescence value was lower than in the control eyes (p < 0.0001). The maximum autofluorescence was related to lens coloration as well as to visual acuity only in nuclear cataract. The regression between maximum autofluorescence and light scatter was statistically significant only in the nuclear cataract group (p = 0.0004). Since the autofluorescence profiles differed not only in height but also in width between the cataract groups, various width/maximum autofluorescence ratios were measured. In nuclear and mixed cataract groups the ratio 75% width/maximum autofluorescence was statistically significantly lower than in other groups (p < 0.0001). In cortical cataracts the ratio (50% width - 75% width)/maximum autofluorescence was statistically significantly higher than in other groups (p < 0.0001).

Light scatter in aging and cataractous human lens.

We measured back light scattering of the human lens with the Lens Opacity Meter 701 in order to determine whether it can be used for objective assessment of lens opacities in various types of cataracts. One-hundred and twenty-seven eyes of 127 individuals were examined including 43 healthy volunteers in various age groups and 84 patients with cortical, nuclear, posterior subcapsular or mixed lens opacities. Almost 90% of the total variation in the light scatter values was accounted for by age in non-cataractous eyes. Mean scatter value of every cataract group was statistically significantly higher than that of age matched healthy controls (p less than 0.0001). Highest scatter values were measured in cortical cataracts while the mean values of other types of cataract were not statistically significantly different from each other. The regression between light scatter and visual acuity was statistically significant for each cataract group. However, large variation of visual acuity was found with scatter values below 60. The results indicate that the Interzeag Lens Opacity Meter is able to identify cataractous and non-cataractous eyes and discern at least advanced cortical cataracts from other types of lens opacities.

Lens autofluorescence in healthy individuals.

We measured blue-green autofluorescence (AF, 495 nm/520 nm) of the lens in 43 random eyes of 43 healthy volunteers aged 6-86 years, five in each decade, using an instrument designed by one of us (HN). The instrument generates an autofluorescence profile, which consists of anterior and posterior juxtacortical peaks and a central plateau. The height of the anterior peak was taken as a maximum autofluorescence value and the square root of the ratio between the posterior and the anterior peak was used as a lens transmission index. The coefficient of variation for the measurement technique was 3.9% for maximum autofluorescence and 2.9% for lens transmission index. Both the maximum autofluorescence and the transmission index were highly correlated with age. Statistically over 90% of the variation in maximum autofluorescence values and almost 70% of the variation in transmission could be attributed to age.