RESUMEN
PURPOSE: To investigate whether macular pigment optical density (MPOD) is related to dark adaptation in healthy subjects. METHODS: Dark adaptation was measured after a minimum 30 % pigment bleach in 33 subjects (aged 15-68), using a white 1° stimulus presented 11° below fixation on a cathode ray tube monitor. The luminance range of the monitor was extended using neutral density filters. A heterochromatic flicker photometry based instrument (MPS 9000) was used to measure MPOD. RESULTS: The average MPOD for the whole group was 0.37 ± 0.21 optical density units. Subjects with lighter irides had on average 40 % lower MPOD compared to those with darker irides (0.3 ± 0.20 vs 0.5 ± 0.19). Group mean MPOD was weakly associated with second (r = 0.32, p = 0.07) and third rod-mediated recovery rates (r = 0.31, p = 0.08) and with the rod threshold (r = -0.24, p = 0.18) 30 min after the onset of bleach. MPOD was unrelated to cone time constant (r = -0.02, p = 0.91), cone threshold (r = -0.01, p = 0.96), rod-cone break (r = 0.13, p = 0.45) or the rod-rod break (r = 0.11, p = 0.52). The second rod-mediated recovery rate (S2) for the lower 10th percentile of MPOD (n = 4) was 0.18 log cd.m(-2).min(-1) and 0.24 log cd.m(-2).min(-1) for the upper 10th percentile (n = 4). The two groups were significantly different (t = -2.67, p = 0.037). CONCLUSIONS: We report a statistically significant difference between subjects falling in the 10th percentile extremes of MPOD and rod-mediated but not cone-mediated sensitivity recovery. Further investigation into the relationship between MPOD and rod function is warranted, particularly extending the work to encompass those with low MPOD and poor night vision.
Asunto(s)
Adaptación a la Oscuridad/fisiología , Luteína/metabolismo , Células Fotorreceptoras de Vertebrados/fisiología , Pigmentos Retinianos/metabolismo , Xantófilas/metabolismo , Adolescente , Adulto , Anciano , Envejecimiento/fisiología , Color del Ojo , Femenino , Voluntarios Sanos , Humanos , Masculino , Persona de Mediana Edad , Fotometría/métodos , Encuestas y Cuestionarios , Agudeza Visual , Adulto Joven , ZeaxantinasRESUMEN
There is a growing body of evidence which suggests that macular pigment (MP), which is entirely of dietary origin, protects against age-related maculopathy. We evaluated the effect of a daily 20 mg lutein ester (equivalent of 10 mg/day free lutein) supplement in patients with early age-related maculopathy (ARM), in terms of macular pigment optical density (MPOD) and plasma concentrations of lutein. MPOD was measured using a flicker photometric technique in seven ARM sufferers and six age-matched controls over a period of supplementation which lasted 18-20 weeks. Plasma lutein increased from a mean (SD) baseline concentration of 182 (127)ng ml(-1) to a peak of 1077 (165)ng ml(-1) in ARM patients, and from 152 (57) to 1110 (605)ng ml(-1) in control subjects. Mean MPOD had increased significantly from baseline of 0.24 to a peak of 0.31 in ARM sufferers. This mean increment of 0.07 was the same for the age-matched controls (baseline: 0.20; peak: 0.27). The augmentation of MP, and plasma concentrations of lutein, following supplementation in subjects with ARM provides the first evidence the disease is not associated with intestinal malabsorption of the relevant macular carotenoids, and that a diseased macula can accumulate and stabilise lutein and/or zeaxanthin. Furthermore, these results suggest that the beneficial effects of lutein supplementation, if any, may be extended to subjects with established ARM.