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Kwadwo Akuffo, Jessica Dennison, Sarah O'Regan, Stephen Beatty, John Nolan, Macular Pigment Research Group; Central Retinal Enrichment Supplementation Trials (CREST): Design and Methodology. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3773.
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To describe the design and methods of the Central Retinal Enrichment Supplementation Trials (CREST). CREST aims to investigate the potential impact of macular pigment (MP) enrichment, following supplementation with a formulation containing 10mg lutein (L), 2mg zeaxanthin (Z) and 10mg meso-zeaxanthin (MZ), on visual performance in normal subjects (Trial 1) and in subjects with early age-related macular degeneration (AMD) (Trial 2).
CREST is a single centre (Waterford, Ireland), double-blind, randomized, placebo-controlled clinical trial. The primary outcome measure is contrast sensitivity at 6cpd. Secondary outcomes include glare disability, photostress recovery, MP, visual acuity, light scatter, reading acuity, reading speed, retinal layer morphology, serum carotenoid concentrations, and cognitive function. AMD morphology will also be assessed in patients in Trial 2, at an accredited AMD reading centre. The criteria for inclusion in Trial 1 is as follows: 18 years +, best corrected visual acuity (BCVA) of 6/6 or better, not more than five dioptres spherical equivalence of refraction, never consumed eye-related dietary supplements containing the macular carotenoids, no ocular pathology, MP at 0.25° less than 0.5 optical density units (ODU). Inclusion criteria for Trial 2 includes: early stage non-visually consequential AMD in at least one eye (between one and eight on the AREDS severity scale), BCVA of 6/12 or better, not more than five dioptres spherical equivalence of refraction, not consumed eye-related dietary supplements containing the macular carotenoids, no other ocular pathology.
Participant enrolment is underway. 120 normal subjects will be recruited into Trial 1 (30 already recruited) and 210 subjects into Trial 2. 79 subjects were screened for eligibility in Trial 1 and 23 (29%) met the inclusion criteria of MP at 0.25° < 0.5 ODU.
CREST will add to the knowledge of the potential of the macular carotenoids L, Z and MZ for vision in normal subjects and in patients with AMD. CREST is the first study to test the effects of supplementation with all three macular carotenoids, including MZ, in the context of a large, double-blind, randomized, placebo-controlled clinical trial.
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