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Macular Pigment (macular + pigment)

Distribution by Scientific Domains
Medical Sciences100%

Terms modified by Macular Pigment

  • macular pigment optical density
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    Selected Abstracts

    Supplementation with the carotenoids lutein or zeaxanthin improves human visual performance

    OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2006
    Jessica Kvansakul
    Abstract Background:, Macular pigment (MP) is found in diurnal primate species when vision spans a range of ambient illumination and is mediated by cone and rod photoreceptors. The exact role of MP remains to be determined. In this study we investigate two new hypotheses for possible MP functions. Objective:, As MP absorption coincides partly with that of rhodopsin, MP may reduce rod signal effectiveness in the mesopic range, thus extend the usefulness of cone-mediated vision into the mesopic range. Forward light scatter in the eye can reduce retinal image contrast. If blue light contributes significantly to intraocular scatter, selective blue light absorption by MP could reduce the effects of scatter. Design:, We investigated 34 subjects from a carotenoid supplementation trial. The measurements included high mesopic contrast acuity thresholds (CATs), macular pigment optical density (MPOD), wavefront aberrations, and scattered light. The measurements were made after 6 months of daily supplementation with zeaxanthin (Z, OPTISHARPÔ), lutein (L), a combination of the two (C), or placebo (P), and again after a further 6 months of doubled supplementation. Results:, The data reveal a trend toward lower CATs in all groups supplemented, with a statistically significant improvement in the lutein group (p = 0.001), although there was no correlation with MPOD. Light scattering in the eye and the root-mean-square wavefront aberrations show decreasing trends as a result of supplementation, but no correlation with MPOD. Conclusions:, The results suggest that supplementation with L or Z increases MPOD at the fovea and at 2.5°, and that supplementation can improve CATs at high mesopic levels and hence visual performance at low illumination. [source]

    Compensation for light loss due to filtering by macular pigment: relation to hue cancellation

    OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2007
    James M. Stringham
    Abstract Background:, A long-standing question in colour vision research is how the visual system is able to correct for the significant absorbance of short wave light by the crystalline lens and macular pigment (MP). Such compensation must be required in order to maintain colour constancy across the retina where MP levels are changing quickly and dramatically. Objective:, We studied this compensation mechanism by measuring MP spatial density profiles and hue cancellation functions across the central retina in a sample of six young healthy subjects. Method:, Yellow (Y, 575 nm)/blue (B, 440 nm) and red (R, 600 nm)/green (G, 501 nm) cancellation functions were obtained at 0, 1, 1.75, 3 and 7° eccentricity. The MP optical density at 460 nm was measured at these same eccentricities using heterochromatic flicker photometry. One subject was assessed repeatedly over a 4-month period during daily supplementation with 30 mg of lutein (L). Results:, Hue cancellation values for the Y/B system did not change across the retina (r = 0.09). In contrast, R/G sensitivity changed as a direct function of MP absorbance (r = 0.99). The Y/B values did not change in the one subject supplemented with 30 mg L daily, despite increases in MP of about 50% over 4 months. Conclusions:, Despite large variations in MP across the retina, hue cancellation values for the Y-B system across the central retina were constant. For example, one subject's MP density declined from a central peak of 0.99 to near zero at 7° (near 90% transmission difference) yet thresholds for the Y/B system were unaffected. In contrast, the G lobe of the R/G system was directly correlated with MP density. Taken together, these results confirm that the Y/B system compensates for MP density, but the R/G system does not. [source]

    4211: Xanthophylls from blood to retina

    ACTA OPHTHALMOLOGICA, Issue 2010
    L BRETILLON
    Xanthophylls are dietary lipophilic compounds. Among them, lutein and zeaxanthin are the major carotenoids found in the human lens and retina, and referred as macular pigment within the retina. Lutein and zeaxanthin cannot be synthesized endogenously. They may therefore be considered as essential and must be provided by adequate dietary intakes. Lutein and zeaxanthin are present in various food items, mainly in plants and fruits such as green vegetables or yellow-orange fruits, as well as in a few animal sources, such as egg yolk. Epidemiological studies consistently suggest that dietary lutein and zeaxanthin are protective factors against the development of Age-Related Maculopathies and Age-related Macular Degeneration. Intervention trials consisting in supplementing the diet with lutein and zeaxanthin demonstrate the bioavailability of those carotenoids in plasma and, in some of them, their efficacy in increasing the density of the macular pigment. An overview will be presented on the mechanisms of xanthophyll bioavailability in blood and retina. [source]

    4214: How to improve macular pigment in retina?

    ACTA OPHTHALMOLOGICA, Issue 2010
    JM LECERF
    [source]

    Investigating the influence of wavelength, light intensity and macular pigmentation on retinal straylight

    ACTA OPHTHALMOLOGICA, Issue 2009
    J ROZEMA
    Purpose To investigate the influence of wavelength, light intensity and macular pigmentation on retinal straylight. This will be tested in both phakic and pseudophakic eyes by means of color filters, as well as by comparing postoperative straylight results of eyes implanted with either clear or blue-blocking IOLs. It has also been suggested in the literature that the yellow macular pigment reduces the effects of the short wavelength components of retinal straylight. Methods In this prospective study the straylight is measured on two groups of pseudophakic subjects: one group of 25 subjects implanted with a clear IOL (Alcon AcrySof SA60AT) and another group of 25 subjects implanted with a yellow IOL (AcrySof Natural SN60AT) using white light as well as with blue, green and red filters. These measurements are repeated on a group of age matched 25 phakic subjects. All retinal straylight measurements will be performed using the Oculus C-Quant straylight meter. In the normal and clear IOL subjects the macular pigment is measured as well using the Tinsley M|Pod device. Results The first, preliminary results demonstrate that in healthy eyes the retinal straylight measured by the Oculus C-Quant depends on the wavelength of the stimulus light. Measurements performed with blue light were lower than those performed in green or red light. Conclusion Stimulus light wavelength appears to have an influence on straylight measurements. Further study on a larger population is required to confirm this trend and to study how IOL color may influence this result in pseudophakic eyes. The possible influence of macular pigment on retinal straylight will be studied simultaneously. [source]

    Pre-receptoral spectral absorption, healthy ageing and pre-clinical indications of retinal disease

    ACTA OPHTHALMOLOGICA, Issue 2009
    E KONSTANTAKOPOULOU
    Purpose The aim of this study was to investigate how chromatic sensitivity changes as a function of age and to establish the extent to which such changes can be attributed to pre-receptoral spectral absorption of short wavelength light and/or changes in retinal mechanisms caused by ageing. Methods The absorption of blue light by the macular pigment (MP) and the crystalline lens and the subjects' sensitivity to rapid flicker were measured using the Macula Assessment Profile (MAP) test. Red-green (RG) and yellow blue (YB) chromatic detection thresholds were measured at the fovea for young and older subjects using the Colour Assessment and Diagnosis (CAD) test at 2.6, 26 and 65 cd/m2. The variables of interest included the spectral absorption of the lens, the optical density of the MP, subject's age and retinal illuminance. Results The absorption of blue light by the lens increased with age. Absorption of blue light by pre-receptoral filters did not affect RG chromatic sensitivity at any of the light levels investigated but had an effect on YB thresholds. The considerably higher colour vision thresholds of some subjects and the subsequent worsening of their chromatic sensitivity at the lower light level may reflect changes in the retina brought about by accelerated aging effects. Conclusion The effect of pre-receptoral absorption of blue light on chromatic sensitivity is small. Ageing affects the amount and spectral composition of the light reaching the photoreceptors and the processing of retinal signals. As a result, flicker sensitivity declines and colour vision deteriorates. Such effects arise mostly from changes in the retina. The MAP and CAD tests help us to detect the effects of accelerated ageing and retinal disease. [source]