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Research Article

Central Retinal Enrichment Supplementation Trials (CREST): Design and Methodology of the CREST Randomized Controlled Trials

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Pages 111-123 | Received 14 Mar 2013, Accepted 03 Sep 2013, Published online: 12 Mar 2014
 

Abstract

Purpose: The Central Retinal Enrichment Supplementation Trials (CREST) aim to investigate the potential impact of macular pigment (MP) enrichment, following supplementation with a formulation containing 10 mg lutein (L), 2 mg zeaxanthin (Z) and 10 mg meso-zeaxanthin (MZ), on visual function in normal subjects (Trial 1) and in subjects with early age-related macular degeneration (AMD; Trial 2).

Methods: CREST is a single center, double-blind, randomized clinical trial. Trial 1 (12-month follow-up) subjects are randomly assigned to a formulation containing 10 mg L, 10 mg MZ and 2 mg Z (n = 60) or placebo (n = 60). Trial 2 (24-month follow-up) subjects are randomly assigned to a formulation containing 10 mg L, 10 mg MZ, 2 mg Z plus 500 mg vitamin C, 400 IU vitamin E, 25 mg zinc and 2 mg copper (Intervention A; n = 75) or 10 mg L and 2 mg Z plus 500 mg vitamin C, 400 IU vitamin E, 25 mg zinc and 2 mg copper (Intervention B; n = 75). Contrast sensitivity (CS) at 6 cycles per degree represents the primary outcome measure in each trial. Secondary outcomes include: CS at other spatial frequencies, MP, best-corrected visual acuity, glare disability, photostress recovery, light scatter, cognitive function, foveal architecture, serum carotenoid concentrations, and subjective visual function. For Trial 2, AMD morphology, reading speed and reading acuity are also being recorded.

Conclusions: CREST is the first study to investigate the impact of supplementation with all three macular carotenoids in the context of a large, double-blind, randomized clinical trial.

Acknowledgements

CREST Research Group

Professor John Nolan, Principal Investigator

Professor Stephen Beatty, Director

Sarah O’Regan, Research Assistant

Jessica Dennison, Trial 1 Researcher

Kwadwo Owusu Akuffo, OD, Trial 2 Researcher

Dr David Kelly, Senior Scientist

DSMC Members

Dr Ailbhe Whyte, Medical Ophthalmologist

Professor James Loughman, Vision Scientist

Dr Michael Harrison, Research Ethics Committee member

Frank Leonard, MSc, Statistician

CREST Pharmacist

Catherine Kelly