Abstract
Purpose: :
To assess the effects of a lutein (L)-based supplement on multifocal electroretinogram (mfERG) N1,P1 and N2 latency, N1P1 amplitude, contrast sensitivity (CS), logMAR distance visual acuity (VA) and macular pigment optical density (MPOD) in healthy eyes. Within the fovea, macular pigment (MP) selectively binds to tubulin within cone photoreceptor axons. Augmentation of MP may influence the mfERG, which allows objective simultaneous recording of cone and bipolar cell function from many retinal areas. Heterochromatic flicker photometry measures MPOD by analysing a subject’s judgement of equiluminance from two lights of different colours at the same location in the visual field. Improvements in MPOD and mfERG amplitudes have been found with L supplementation in eyes with age-related macular disease (ARMD).
Methods: :
Fifty-two participants were randomly allocated to either supplement or non-supplement groups. All attended for three visits (baseline, 20 weeks and 40 weeks) before unmasking occurred. There were 25 in the treated group aged 18-77 (mean ± sd: 48.7 ± 17.4 years) and 27 in the non-treated group aged 21-69 (mean ± sd: 43.9 ± 16.2 years). Dietary analysis showed no difference for either group over the study period.
Results: :
The sample size provided 80% power at the 5% significance level for all outcome measures despite the fact that due to technical difficulties not all participants completed mfERG testing. Mixed between-within analysis of variance showed no difference between treated and non-treated groups for VA, CS or mfERG measures. The treated group showed an increase in MPOD compared to the non-treated group (F =4.235, p = 0.020) over time.
Conclusions: :
Increase in MPOD with a L-based supplement has not translated into improved objective or subjective measures of visual function. Although MP binds to tubulin in cone photoreceptors, an increase in MPOD has not conferred improvements in VA, CS or the cone-driven mfERG. The protective effects of MP may not translate into improved measures of visual function for many years.
Clinical Trial: :
http://www.isrctn.org 17842302
Keywords: macular pigment • carotenoids/carotenoid binding proteins • electroretinography: clinical