Abstract
Purpose: :
To investigate the impact of three different macular carotenoid interventions on macular pigment optical density (MPOD), in subjects with early age-related macular degeneration (AMD).
Methods: :
Seventy-five subjects (75 study eyes) with early AMD were recruited into this single-blind, randomised clinical trial. Stereo fundus photographs were graded at the accredited reading centre at the University of Wisconsin, USA. AMD was defined as the presence of drusen and pigmentary changes. Of the 75 eyes, 9 were classified as having "atypical-AMD" (i.e. the presence of pigmentary changes only). Subjects were randomly assigned into one of the three intervention groups, as follows: Group 1 (n = 25): L = 20 mg/day, zeaxanthin (Z) = 2 mg/day; Group 2 (n = 28): meso-zeaxanthin (MZ) = 10 mg/day, L = 10 mg/day, Z = 2 mg/day; Group 3 (n = 22): MZ = 17 mg/day, L = 3 mg/day, Z = 2 mg/day. MPOD was measured using customised heterochromatic flicker photometry at four retinal eccentricities (0.25°, 0.5°, 1.0° and 1.75°) and visual function was assessed using a range of psychophysical tests. Study visits occurred at baseline, three, six and 12 months.
Results: :
Twenty-eight (37%) of the subjects were male. Mean (±sd) values at baseline were, as follows: age (years) = 67.2 (±8.4); MPOD (at 0.25°) = 0.47 (±0.23); corrected distance visual acuity (CDVA) = 97.4 (±7.6) (circa. LogMAR: 0.05). Positive and statistically significant relationships between MPOD (at 0.25°) and visual function at baseline included: CDVA, letter contrast sensitivity, measures of grating contrast sensitivity and glare disability (r = 0.239-0.357; p<0.05, for all). Longitudinal analysis demonstrated a statistically significant increase in MPOD at 0.25° in Group 2 only (p=0.003); at 0.5° in Groups 1 and 2 (p = 0.043 and p = 0.001, respectively); at 1.0° in Group 2 only (p = 0.012); at 1.75° in Groups 1 and 2 (p = 0.046 and p = 0.002, respectively).
Conclusions: :
Cross-sectional analysis shows that MPOD correlates positively with important measures of visual function, in subjects with early AMD. In addition, we found that enrichment of MP across its spatial profile can be best achieved following supplementation with all three macular carotenoids (L, MZ and Z), for subjects with the disease. The morphological and functional implications of these findings merit investigation, and will follow.
Clinical Trial: :
www.controlled-trials.com, ISRCTN81595685
Keywords: macular pigment • carotenoids/carotenoid binding proteins