Purpose: The high-performance visual function associated with central vision is mediated by the macula (the central retina), which accumulates three diet-derived pigments (the carotenoids lutein [L], zeaxanthin [Z], and meso-zeaxanthin [MZ]). Our study sought to investigate the impact on visual function, including contrast sensitivity (CS), of supplementation with these naturally occurring carotenoids, in individuals with low retinal concentrations.
Methods: Subjects consumed daily a formulation containing 10 mg L, 2 mg Z, and 10 mg MZ (active group; n = 53) or placebo (n = 52) for a period of 12 months. Study visits were at baseline, 3, 6, and 12 months. Contrast sensitivity at 6 cycles per degree (cpd) was the primary outcome measure (POM). Secondary outcome measures included CS at other spatial frequencies, best-corrected visual acuity (BCVA), glare disability, photostress recovery, and light scatter. Macular pigment optical density (MPOD) was measured using dual-wavelength autofluorescence, and serum carotenoid concentrations were analyzed using high performance liquid chromatography (HPLC).
Results: Compared to placebo, statistically significant improvements from baseline CS were detected at 6 (P = 0.002) and 1.2 (P = 0.004) cpd in the active group. Additionally, improvements in CS were commensurate with the observed increases in retinal concentrations of these carotenoids (r = 0.342, P = 0.002 at 6 cpd).
Conclusions: These results indicate that dietary fortification with the macular carotenoids can have meaningful effects on visual function.