Assessment of Maternal Macular Pigment Optical Density (MPOD) as a Potential Marker for Dietary Carotenoid Intake during Lactation in Humans.

Pregnancy and lactation can change the maternal nutrient reserve. Non-invasive, quantitative markers of maternal nutrient intake could enable personalized dietary recommendations that improve health outcomes in mothers and infants. Macular pigment optical density (MPOD) is a candidate marker, as MPOD values generally reflect carotenoid intake. We evaluated the association of MPOD with dietary and breastmilk carotenoids in postpartum women. MPOD measurements and dietary intake of five carotenoids were obtained from 80 mothers in the first three months postpartum. Breastmilk samples from a subset of mothers were analyzed to determine their nutrient composition. The association between MPOD and dietary or breastmilk carotenoids was quantitatively assessed to better understand the availability and mobilization of carotenoids. Our results showed that dietary α-carotene was positively correlated with MPOD. Of the breastmilk carotenoids, 13-cis-lutein and trans-lutein were correlated with MPOD when controlled for the total lutein in breastmilk. Other carotenoids in breastmilk were not associated with MPOD. Maternal MPOD is positively correlated with dietary intake of α-carotene in the early postpartum period, as well as with the breastmilk content of lutein. MPOD may serve as a potential marker for the intake of carotenoids, especially α-carotene, in mothers in the early postpartum period.

Is macular pigment optical density really involved in fixation preference?

PURPOSE: To evaluate macular pigment optical density in healthy children and to compare the values with those of strabismic children with respect to fixation preference. METHODS: The study recruited 54 healthy and 41 strabismic children. Two groups were matched in terms of gestational age, birth weight, and body mass index. All participants underwent complete ophthalmological evaluation and macular pigment optical density measurement and filled a self-reported food frequency questionnaire. Strabismic children were categorized according to fixation preference. RESULTS: The mean age was 9.87 ± 2.39 years in healthy children and 9.07 ± 2.07 years in children with strabismus (p = 0.091). Mean macular pigment optical density was 0.23 ± 0.25 in healthy eyes and 0.25 ± 0.27 in non-preferred eyes of strabismic children (p = 0.964). Macular pigment optical density was significantly higher in preferred eyes of strabismic children (0.43 ± 0.34) compared to non-preferred eyes (p = 0.004) and healthy eyes (p = 0.001). There was a difference of macular pigment optical density between both eyes in patients with grades 1, 2, and 3 fixation preference, whereas patients with grade 4 preference had similar macular pigment optical density in both eyes (p = 0.008). There was a statistically significant positive correlation between macular pigment optical density in preferred eyes and body mass index (r = 0.354, p = 0.023). CONCLUSION: Preferred eyes of children with strabismus seem to have higher macular pigment optical density readings. This difference may emerge from the higher tendency of recognizing the flicker stimulus while preferred eye is under testing. Similar macular pigment optical density in healthy and non-preferred eyes and the fact that both lower than preferred eyes remain unexplained. It should be kept in mind that macular pigment optical density results should be carefully interpreted and macular pigment optical density in cases with strabismus should be further investigated.

Effect of intraocular scattering in macular pigment optical density measurements.

Fundus reflectometry is a common in-vivo, noninvasive method to estimate the macular pigment optical density (MPOD). The measured density, however, can be affected by the individual's intraocular scattering. Scattering causes a reduction in the contrast of the fundus image, which in turn leads to an underestimation of the measured density. Intraocular scattering was measured optically in a group of seven young, healthy subjects using the method of optical integration and was subsequently used to correctly estimate the MPOD from fundus images. It was shown that when scattering is not considered, the measured optical density using fundus reflectometry can be underestimated by as high as 16% for our group of subjects.

What do we know about the macular pigment in AMD: the past, the present, and the future.

Carotenoids are lipophilic isoprenoid pigments with a common C40H56 core chemical structure that are naturally synthesized by many plants, algae, bacteria, and fungi. Humans and animals cannot synthesize carotenoids de novo and must obtain them solely through dietary sources. Among the more than 750 carotenoids in nature, only lutein, zeaxanthin, meso-zeaxanthin, and their oxidative metabolites selectively accumulate in the foveal region of the retina where they are collectively referred to as the macular pigment (MP) of the macula lutea. MP serves an ocular protective role through its ability to filter phototoxic blue light radiation and also via its antioxidant activity. These properties have led to the hypothesis that carotenoids may protect against the development of age-related macular degeneration (AMD), the most common cause of blindness in the aged population >60 years old. Epidemiological studies have supported this by showing that patients with lower concentrations of serum carotenoids and macular pigment optical density (MPOD) measurements are at a higher risk of developing AMD. Conversely, nutritional supplementation and diets rich in lutein and zeaxanthin readily impact MP concentrations and reduce the risk of progression to advanced AMD, and the AREDS2 supplement formulation containing 10 mg of lutein and 2 mg of zeaxanthin is the standard-of-care recommendation for individuals at risk for visual loss from advanced AMD. This article reviews the rich history of research on the MP dating back to the 1700s and outlines their potential for further therapeutic improvements for AMD in the future.

Clinical imaging of macular pigment optical density and spatial distribution.

Clinical research continues to provide an increasing number of studies that reveal an association between macular pigment optical density (MPOD) and both visual function and ocular health. As a result, there is a growing need for repeatable, accurate measures of MPOD that can describe peak optical density as well as spatial distribution. Measurement of MPOD in a research setting has an established history encompassing a number of both objective and subjective techniques. Transition of these techniques to a clinical setting has produced an array of commercial devices using three primary methods: heterochromatic flicker photometry, fundus autofluorescence and fundus reflectometry. The inherent differences among the techniques create difficulty in making direct comparisons between MPOD measurement devices. Understanding the limitations of each technique is critical in the clinical interpretation of MPOD results. Here, both the objective and subjective methods of MPOD measurement are reviewed with emphasis on the commercially available devices used in clinical settings.

Perception of Haidinger Brushes in Macular Disease Depends on Macular Pigment Density and Visual Acuity.

PURPOSE: To optimize the perceptibility of Haidinger brushes (HB) and to investigate its association with visual acuity and macular pigment density. METHODS: In this prospective cross-sectional study, each subject underwent best-corrected visual acuity (BCVA) testing, funduscopy, and assessment of macular pigment optical density (MPOD) using the two-wavelength fundus autofluorescence method. Haidinger brush visibility was tested with a rotating linear polarizer and a controllable three-color light-emitting diode (LED) panel as light source. A simple model of macular pigment absorption was used to predict HB visibility as a function of stimulus wavelength and MPOD. RESULTS: All control eyes (n = 92) and 34% of the 198 eyes of subjects with macular disease (age-related macular degeneration, n = 40; macular telangiectasia type 2, n = 52; Stargardt disease, n = 58; other retinal dystrophies, n = 48) perceived HB when an optimized test setup (464-nm LED light) was applied. The degree of psychophysical perception and the dependency on different wavelengths were in accordance with the absorptance model. In eyes of subjects with macular disease, minimum thresholds of MPOD and BCVA required for HB perception were identified. Subjects with macular telangiectasia type 2 showed lowest values of MPOD and were mostly unable to perceive HB despite relatively preserved BCVA. CONCLUSIONS: Macular pigment and a relatively preserved foveal function are necessary for the perception of HB. Haidinger brushes are usually not perceived by subjects with macular telangiectasia type 2, likely due to their characteristic foveal depletion of macular pigment.

The Spatial Profile of Macular Pigments Is Related to the Topological Characteristics of the Foveal Avascular Zone.

PURPOSE: Macular pigments are preferentially concentrated in the central fovea, an area devoid of vasculature. We hypothesized that there may be a link between the macular pigment profile and the size and structural characteristics of the foveal avascular zone (FAZ). METHODS: Two-wavelength autofluorescence method was used to quantify macular pigment optical density (MPOD) and the radius at half peak of MPOD, which was defined as the retinal eccentricity where the MPOD value was 50% of the peak value. Volumetric spectral-domain optical coherence tomography (OCT) images of the macula were obtained from 32 subjects. The equivalent radius of the FAZ was determined using data generated from OCT angiography. Generalized estimating equations were used to test the hypothesis that there are interrelationships among the central foveal thickness, peak MPOD, the radius at half peak of MPOD and the equivalent radius of the FAZ. RESULTS: The equivalent radius of the FAZ was highly correlated with the radius at half peak of MPOD (P < .001). The equivalent radius of the FAZ was a significant predictor for central foveal thickness (P < .001). The significant predictor for peak MPOD was central foveal thickness (P = .004). Eyes with larger FAZs were more likely to have a secondary peak in their MPOD spatial profile in a zone ranging from 0.5 to 1.0 degrees from the foveal center. CONCLUSIONS: The spatial distribution of macular pigment is related to the size of the FAZ, in addition to the central foveal thickness. It is possible that xanthophyll pigment accumulation in the macula serves functions, such as attenuation of shorter wavelengths of light, that would have been provided by the light-filtering characteristics of blood vessels.

Impact of Macular Pigment on Fundus Autofluorescence Lifetimes.

PURPOSE: To characterize the macular region and to investigate the influence of the macular pigment (MP) on fundus autofluorescence (FAF) lifetimes in vivo. METHODS: Forty-eight healthy subjects with a mean age of 24.1 ± 3.6 years (range, 20-37 years) were included. A 30° retinal field was investigated using the fluorescence lifetime imaging ophthalmoscope (FLIO), based on a Heidelberg Engineering Spectralis system, detecting FAF decays in a short (498-560 nm; ch1)- and a long (560-720 nm; ch2)-wavelength channel. The mean fluorescence lifetime τm was calculated from a 3-exponential approximation of the FAF decays. Macular pigment optical density (MPOD) was measured by one-wavelength reflectometry, and macular optical coherence tomogram (OCT) scans were recorded. Correlations between τm and MPOD were analyzed. RESULTS: The τm showed shortest values at the macular region with a mean of 82 ps (ch1) and 126 ps (ch2). We found a strong correlation of τm to the MPOD (ch1: r = -0.760; ch2: r = -0.663; P < 0.001), as well as a topologic agreement of shortest τm with highest MPOD. CONCLUSIONS: Macular pigment, which is known to have very short fluorescence decays, considerably contributes to the macular autofluorescence (AF). This study gives indirect evidence for a strong impact of MP on macular τm, although no direct measurement of MP autofluorescence lifetimes in vivo is possible at this point. Potentially, imaging the FAF lifetimes could lead to a novel methodology for the detection of macular pigment properties and pathology-induced changes in the living human retina.

Autofluorescence imaging of macular pigment: influence and correction of ocular media opacities.

The healthy adult human retina contains in its macular region a high concentration of blue-light absorbing carotenoid compounds, known as macular pigment (MP). Consisting of the carotenoids lutein, zeaxanthin, and meso-zeaxanthin, the MP is thought to shield the vulnerable tissue layers in the retina from lightinduced damage through its function as an optical attenuator and to protect the tissue cells within its immediate vicinity through its function as a potent antioxidant. Autofluorescence imaging (AFI) is emerging as a viable optical method for MP screening of large subject populations, for tracking of MP changes over time, and for monitoring MP uptake in response to dietary supplementation. To investigate the influence of ocular media opacities on AFI-based MP measurements, in particular, the influence of lens cataracts, we conducted a clinical trial with a large subject population (93 subjects) measured before and after cataract surgery. General AFI image contrast, retinal blood vessel contrast, and presurgery lens opacity scores [Lens Opacities Classification System III (LOCS III)] were investigated as potential predictors for image degradation. These clinical results show that lens cataracts can severely degrade the achievable pixel contrasts in the AFI images, which results in nominal MP optical density levels that are artifactually reduced. While LOCS III scores and blood vessel contrast are found to be only a weak predictor for this effect, a strong correlation exists between the reduction factor and the image contrast, which can be quantified via pixel intensity histogram parameters. Choosing the base width of the histogram, the presence or absence of ocular media opacities can be determined and, if needed, the nominal MP levels can be corrected with factors depending on the strength of the opacity.