Nuclear Cataract, Lutein and Zeaxanthin

Nuclear cataract is the most common type of cataract among older Americans, and the most common type for which cataract surgery is performed. It occurs more often in women than men and among Caucasian individuals.

The pathogenesis of nuclear cataract is known to involve the inability to sufficiently defend against or repair the damage due to a variety of environmental stressors, including photochemical formation of free radicals. Lutein and zeaxanthin are the most abundant lens carotenoids. They scavenge superoxide and hydroxyl radicals, protect against UV B-induced lipid peroxidation, and may play a role in membrane stability. Diets high in lutein plus zeaxanthin have also been inversely associated with nuclear cataract or cataract extraction in several previous observational studies.

The Carotenoids in Age-Related Eye Disease Study (CAREDS) is an ancillary study of the Women's Health Initiative (WHI). The authors of CAREDS previously found that a stable intake of lutein and zeaxanthin over time could reduce the risk of AMD by about 43% in healthy women under 75 (1) [see EduFacts Vol. 6 No. 9]. The CAREDS investigators now report that diets high in lutein and zeaxanthin are also linked to a lower prevalence of nuclear cataract (2).

Study Design and Methods

A total of 1802 women aged 50 to 79 years with intakes of lutein and zeaxanthin above the 78th (high) and below the 28th (low) percentiles in the WHI were recruited 4 to 7 years later into CAREDS. The primary outcome was nuclear cataract, defined as a nuclear sclerosis severity score of 4 or greater in the worst eye and/or a history of cataract extraction in either eye.

Nuclear cataract was determined from slit lamp photographs. Dietary estimates were made from responses to a validated, semi-quantitative food frequency questionnaire. Serum levels of lutein, zeaxanthin, and tocopherols were determined at Tufts University by a reverse-phase HPLC analysis.

Results

Women in the group with high dietary levels of lutein and zeaxanthin had a 23% lower prevalence of nuclear cataract (age-adjusted odds ratio, 0.77; 95% CI, 0.62-0.96) compared with the low level group. (Table 2)

Women in the highest quintile category of diet or serum levels of lutein and zeaxanthin as compared with those in the lowest quintile category were 32% less likely to have nuclear cataract (multivariable adjusted odds ratio, 0.68; 95% CI, 0.48-0.97; P for trend=.04; and multi-variable-adjusted odds ratio, 0.68; 95% CI, 0.47-0.98; P for trend=.01, respectively). The associations were similarly strong for serum concentrations of the combined carotenoids.

Comments

The observed association between these carotenoids and nuclear opacity was stronger when examining intake of lutein plus zeaxanthin across all of the levels of intake in this sample (by quintile categories) than when comparing the 2 groups of women sampled who had lutein and zeaxanthin intakes above the 78th and below the 28th quintiles. The results from CAREDS are consistent with a body of evidence that supports a protective relationship between lutein and zeaxanthin and nuclear cataract.

References

1. Moeller SM et al. Age-Related Macular Degeneration and Lutein and Zeaxanthin in the Carotenoids in Age-Related Eye Disease Study (CAREDS). Arch of Ophthalmology 124:1151-1162, 2006.
2. Moeller SM et al. Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in the Age-Related Eye Disease Study (CAREDS), an ancillary study of the WHI. Arch Ophthalmol 126:354-364, 2008.