Macular pigment optical density in a midwestern sample

Macular Pigment Optical Density and Skin Carotenoids in a Childhood Sample

BACKGROUND

Carotenoids are plant pigments with light filtering and antioxidant properties that deposit in human tissues, including retina and skin. Descriptive characteristics and covariates of carotenoid status in macula and skin have been examined in adults; however, similar studies in children are limited. Thus, this study aimed to delineate how factors of age, sex, race, weight status, and dietary carotenoid intake relate to macular and skin carotenoids in children.

METHODS

Children (7-13 y, N = 375) completed heterochromatic flicker photometry to assess macular pigment optical density (MPOD). Participants underwent anthropometrics to measure weight status (BMI percentile [BMI%]), and parent/guardian provided demographic information. Subsample data were available for skin carotenoids (N = 181), assessed using reflection spectroscopy, and dietary carotenoids (N = 101) using the Block Food Frequency Questionnaire. Relationships between skin and macular carotenoids were assessed using partial Pearson's correlations controlling for age, sex, race, and BMI%. Relationships between dietary carotenoids and macular and skin carotenoids were assessed using stepwise linear regression including age, sex, race, and BMI% in the model.

RESULTS

Mean MPOD was 0.56 ± 0.22 and skin carotenoid score was 282 ± 94.6. There was no significant correlation between MPOD and skin carotenoids (r = 0.02, P = 0.76). BMI% was negatively associated with skin (stdβ = -0.42, P < 0.001), but not macular carotenoids (stdβ = -0.04, P = 0.70). Neither MPOD nor skin carotenoids were associated with age, sex, or race (all P > 0.10). MPOD was positively associated with energy-adjusted reported lutein + zeaxanthin intake (stdβ = 0.27, P = 0.01). Skin carotenoids were positively associated with energy-adjusted reported carotenoid intake (stdβ = 0.26, P = 0.01).

CONCLUSIONS

The mean MPOD values in children were higher than what has been reported in adult populations. Previous studies in adult samples report an average MPOD of 0.21. Although macular and skin carotenoids were not related, they were associated with dietary carotenoids relevant to the respective tissues; however, skin carotenoids may be more susceptible negative influence from higher weight status.

A Dietary Strategy for Optimizing the Visual Range of Athletes

Visual range is quantified by assessing how far one can see clearly (an ability crucial to many athletes). This ability tends to vary significantly across individuals despite similar personal characteristics. We hypothesize that the primary driver of these differences is the individual response to scattered short-wave light in the environment moderated by the dietarily derived retinal pigments lutein and zeaxanthin.

Macular pigment optical density responses to different levels of zeaxanthin in patients with high myopia

PURPOSE

Measurement of macular pigment optical density (MPOD) can be conducted to assist in the diagnosis of multiple fundus diseases.

METHODS

Fifty-four subjects with high myopia were prospectively recruited for a 3-month clinical trial. Detailed ophthalmologic examinations and MPOD measurements were performed. The subjects in each high myopia category group were randomly subdivided into 5 intervention groups, including a low-dose Lycium barbarum group (10 g Lycium barbarum, containing 10 mg of zeaxanthin and 1 mg of lutein), low-dose control group (1 mg of lutein), high-dose Lycium barbarum group (20 g of Lycium barbarum, containing 20 mg of zeaxanthin and 2 mg lutein), high-dose control group (2 mg of lutein), and a blank control group. Differences in the MPODs among the high myopia groups were calculated with Welch two-sample t tests. A linear mixed-effects model was constructed and Pearson's correlation analysis was performed to determine correlations between MPOD and other factors. The MPOD values at baseline and the 3-month follow-up were compared with the Mann-Whitney test.

RESULTS

The category 1 group had a significantly higher MPOD than the category 2 (P = 0.02) and category 3 groups (P < 0.001). The category 2 group had a significantly higher MPOD than the category 3 group (P < 0.001). The MPOD significantly decreased with increasing axial length (AL) and decreasing best-corrected visual acuity (BCVA) in the category 1-3 groups and with increasing age and increasing intraocular pressure (IOP) in the category 2-3 groups. The MPOD was significantly higher in the group who received high-dose zeaxanthin from Lycium barbarum than in the group who received high-dose lutein at 3 months (P = 0.0403), while no significant difference was identified between the low-dose zeaxanthin group and low-dose lutein group (P = 0.1117).

CONCLUSIONS

The MPOD was negatively correlated with the category of high myopia. Supplementation of zeaxanthin from Lycium barbarum is beneficial in preventing the loss of macular pigment of high myopia patients.

TRIAL REGISTRATION

Trial registration number and date of registration: ChiCTR2100046748.

Macular pigment optical density in central serous chorioretinopathy

Purpose

The aim of our study was to evaluate the macular pigment optical density in patients with acute and chronic central serous chorioretinopathy and to describe the association between central retinal thickness and choroidal thickness with the macular pigment optical density.

Materials and Methods

Eyes with acute central serous chorioretinopathy and chronic central serous chorioretinopathy (patients, who were diagnosed as having disease activity for 6 months) were included in this study. Macular pigment was measured using the heterochromatic flicker technique of the MPS II device for both eyes in patients with acute and chronic central serous chorioretinopathy and in control subjects.

Results

Twenty-seven eyes with acute central serous chorioretinopathy, 23 eyes with chronic central serous chorioretinopathy, and 25 control eyes were enrolled. The mean macular pigment optical density in chronic central serous chorioretinopathy (0.480 ± 0.16 density unit (95% confidence interval: 0.390-0.570) was found to be significantly lower than in the control eyes (0.571 ± 0.128 density unit) (95% confidence interval: 0.480-0.670) (p = 0.007). In correlation analysis, no significant association was detected between the central retinal thickness, choroidal thickness, and macular pigment optical density values in central serous chorioretinopathy group (p = 0.31, p = 0.71).

Conclusion

Macular pigment optical density levels were significantly lower in chronic central serous chorioretinopathy patients than in controls, possibly due to degeneration of the neurosensorial retina, as a result of the long-term persistence of subretinal fluid. There was not a significant correlation between choroidal thickness and macular pigment optical density levels in central serous chorioretinopathy group.

Foveal macular pigment dip in offspring of age-related macular degeneration patients is inversely associated with omega-3 index

Background

Offspring of parent(s) with age-related macular degeneration (AMD) have a 45% lifetime risk of developing the disease. High foveal macular pigment optical density (MPOD) is protective, whereas individuals with a “foveal macular pigment dip” (FMPD) are at increased risk. Shortage of the dietary carotenoids lutein, zeaxanthin as well as fish consumption are reported AMD risk factors. This Early Biomarkers of AMD (EBAMD) study evaluates serum factors that protect foveal MPOD architecture in Caucasian offspring of parent(s) with AMD.

Methods

N = 130 subjects [mean (SD) age 62.8 (8.6) years; 36/94 male/female] were recruited from Scripps Health/ Scripps Memorial Hospital/ Scripps Mericos Eye Institute between 2012 and 2017. Macula pigment 3D topography was evaluated using specular reflectance. Buccal genetic cheek swab, circulating serum dietary carotenoids and long-term RBC omega-3 fatty acid status, as well as common secondary clinical structural and vision function parameters were obtained.

Results

41 % of offspring of AMD parent(s) presented with FMPD. These offspring were about 4 years younger than those without FMPD (controls; P = 0.012) and had thinner foveas (P = 0.010). There were no differences in gender, BMI, % body fat, visual acuity or contrast sensitivity between those with and without FMPD. % RBC membrane docosahexaenoic acid (DHA) was reduced in FMPD offspring vs. control offspring (P = 0.04). The Omega-3 Index was significantly decreased in the FMPD group (P = 0.03).

Conclusions

The percentage of FMPD in AMD offspring is nearly twice that reported for the general population in the scientific literature. Offspring presenting FMPD had similar AMD genetic risk, but significantly reduced % RBC membrane omega-3 fatty acids and thinner foveas compared with those without FMPD. Our data supports the importance of ‘essential fatty’ acids as an independent AMD risk factor.

Evaluation of Macular Pigment Optical Density in Healthy Eyes Based on Dual-Wavelength Autofluorescence Imaging in South Indian Population

Purpose

To estimate macular pigment optical density (MPOD) values across different age groups in the South Indian population across various spatial profiles using dual-wavelength autofluorescence.

Methods

Sixty eyes of 31 healthy subjects underwent MPOD measurement with Spectralis HRA+OCT. The average MPOD and macular pigment optical volume (MPOV) at 1°, 2°, and 6° radii, the mean MPOD in the classical Early Treatment Diabetic Retinopathy Study (ETDRS) grid, and the spatial profiles of two different age groups across 12 plots covering the radial sectors were recorded.

Results

The mean age was 39.1 ± 12.7 years. The mean MPOD and MPOV values were 0.38 ± 0.11 and 787.95 ± 225.13 at 1° eccentricity, 0.23 ± 0.08 and 2000 ± 708.24 at 2° eccentricity, and 0.05 ± 0.02 and 4335 ± 2007.71 at 6° eccentricity, respectively. In the ETDRS grid, the mean MPOD was found to be highest in the central sector and lowest in the inferior peripheral ring. We also found that along the radial sectors the lower quadrants tended to have low MPOD as compared to the upper quadrants. Subjects 40 years of age or older had significantly higher averaged MPOD in certain areas (–15° to 15° and 75° to 105°) along the radial sectors than subjects less than 40 years of age.

Conclusions

This study establishes a reference value for future studies of diseased eyes in the South Indian population.

Translational Relevance

Our study is unique in that it reports MPOD among the South Indian population across different age groups, as well as the distribution of MPOD in all nine zones of the classical ETDRS grid and various spatial profiles covering the 30° radial sectors centered on the fovea.

Differences in macular pigment optical density across four ethnicities: a comparative study

Objective:

The aim of this study is to compare macular pigment optical density levels across four different ethnicities and study its influence on ganglion cell layer and retinal nerve fibre layer thickness across these ethnicities.

Methods:

Consenting adults visiting the ophthalmology and optometry clinics for a routine eye examination without any ocular comorbidity were enrolled. Participants underwent optical coherence tomography for macular thickness, retinal nerve fibre layer thickness and ganglion cell layer thickness. The macular pigment optical density levels were determined in the dominant eye using the QuantifEye device by trained observers.

Results:

In total, 336 eyes of 336 participants with a mean age of 39.2 ± 14.4 years were included of which 103 (30%) were Caucasians, 111 (33%) were African Americans, 29 (9%) were South Asian Indians and 94 (28%) were Hispanics. The mean macular pigment optical density value across the entire study population was 0.47 ± 0.15. South Asian Indians (0.58 ± 0.16) and Hispanics (0.52 ± 0.15) had significantly higher mean macular pigment optical density values compared with Caucasians (0.41 ± 0.16) and African Americans (0.38 ± 0.15). Linear regression analysis showed that there was a significant association between ethnicities and macular pigment optical density values when adjusted for age (β coefficient = 0.31, 95% confidence interval = 0.029–0.58, p < 0.001 for South Asian Indian and Hispanic ethnic groups compared with African Americans). There were no differences in the retinal nerve fibre layer and ganglion cell layer thickness across ethnic groups. Linear regression analysis also did not reveal any significant association between macular pigment optical density levels and retinal nerve fibre layer or ganglion cell layer thickness.

Conclusion:

Caucasians and African Americans have lower macular pigment optical density compared with South Asian Indians and Hispanics. There is no clinically significant association between macular pigment optical density levels and retinal nerve fibre layer and ganglion cell layer thickness in healthy individuals across races.

Lutein across the Lifespan: From Childhood Cognitive Performance to the Aging Eye and Brain

Lutein is a non-provitamin A dietary carotenoid found in dark green leafy vegetables, corn, eggs, and avocados. Among the carotenoids, lutein and its isomer, zeaxanthin, are the only 2 that cross the blood-retina barrier to form macular pigment in the retina. Lutein also preferentially accumulates in the human brain across multiple life stages. A variety of scientific evidence supports a role for lutein in visual as well as cognitive function across the lifespan. The purpose of this review is to summarize the latest science on lutein's role in the eye and the brain across different ages.

Investigating the potential of Zernike polynomials to characterise spatial distribution of macular pigment

It has been postulated that particular patterns of macular pigment (MP) distribution may be associated with the risk for eye diseases such as age-related macular degeneration (AMD). This work investigates the potential of Zernike polynomials (ZP) to characterise the level and distribution of MP, and their suitability as a representation for analysis of the effects of age and AMD on MP patterns. As the case study, MP distribution maps computed using an experimental method based on fundus reflectance (MRIA) were obtained for ninety volunteers representing three groups: under-fifty without AMD, fifty and over without AMD, and fifty and over with AMD. ZP with 105 coefficients were fitted to the maps using least-squares optimisation and found to represent MP maps accurately (RMSE<10⁻¹). One-way MANOVA analysis carried out on ZP representations showed that the three subject groups have significantly different means (Wilk’s Lambda 0.125, p<0.0001). Linear discriminant analysis with leave-one-out scheme resulted in accuracy, sensitivity and specificity of classification according to, respectively, disease status regardless of age (81% all); disease status in the age-matched groups (87%, 88%, 86%); age irrespective of disease status (81%, 83%, 73%); and age for subjects without AMD (83%, 88%, 80%). Mean MP distributions computed from ZP coefficients for the three groups showed more elevated and more peaked MP for the healthy under-fifty group; more irregular and more elevated peripheral levels in over-fifty AMD group than in over-fifty non-AMD group; and moderate radial asymmetry in non-AMD over-50 group. The results suggest that ZP coefficients are capable of accurately representing MP in a way that captures certain spatial patterns of its distribution. Using the ZP representation MP maps could be classified according to both age and disease status with accuracy significantly greater than chance, with peak elevation, pattern irregularity and radial asymmetry identified as important features.

Lutein Intake and Blood Lutein Concentration Are Positively Associated with Physical Activity in Adults: A Systematic Review

Lutein is a carotenoid that reduces the risk of some chronic diseases, possibly by altering physical activity behavior. The objective of this study was to conduct a systematic review of studies examining the relationship between lutein status (dietary intake/blood concentration) and physical activity. Peer-reviewed studies published in Medline, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Scopus, and Embase were included if they reported a measure of association between lutein status and physical activity. Seventeen studies met the inclusion criteria. Eleven reported positive associations, three reported mixed results, and three reported no association. Two studies used objective measures of lutein status (blood concentration) and physical activity (accelerometry) and reported positive associations, with correlations of ≥0.36 and differences of ≥57% in physical activity between upper and lower tertiles. Studies using self-report measures reported weaker correlations (r = 0.06 to 0.25), but still more physical activity (18% to ≥600% higher) in those with the highest compared with the lowest lutein status. Higher lutein status may be associated with higher levels of physical activity, which may contribute to a reduced risk of chronic disease.

Effect of Long-Term Xanthophyll and Anthocyanin Supplementation on Lutein and Zeaxanthin Serum Concentrations and Macular Pigment Optical Density in Postmenopausal Women

Xanthophylls (lutein, L; zeaxanthin, Z) and anthocyanins are often included in food supplements to improve ocular health. There are no dietary reference intakes for them. The aim was to assess the effects of L, Z and anthocyanin supplementation on short and long-term lutein status markers (serum concentration and macular pigment optical density (MPOD)). Seventy-two postmenopausal women were randomized into a parallel study of 8 months: Group A-anthocyanines (60 mg/day); Group X-xanthophylls (6 mg L + 2 mg Z/day); Group X+A-anthocyanines (60 mg/day) + xanthophylls (6 mg L + 2 mg Z/day). At the beginning of the study, 4 and 8 month serum L and Z concentrations were determined (HPLC), as well as L, Z and anthocyanine dietary intake and MPOD (heterochromic flicker photometry). Baseline concentrations of L (0.35 ± 0.19 μmol/L), Z (0.11 ± 0.05 μmol/L), L+Z/cholesterol/triglycerides (0.07 ± 0.04 μmol/mmol) increased in Group X (2.8- and 1.6-fold in L and Z concentrations) and in group XA (2- and 1.4-fold in L and Z concentrations). MPOD (baseline: 0.32 ± 0.13 du) was not modified in any of the groups at the end of the study. There were no differences in the dietary intake of L+Z and anthocyanin at any point in time in any group. Supplementation of L and Z at a dietary level provoked an increase in their serum concentration that was not modified by simultaneous supplementation with anthocyanins.

Rod-Mediated Dark Adaptation and Macular Pigment Optical Density in Older Adults with Normal Maculas

PURPOSE

To examine the association between macular pigment optical density (MPOD) and rod-mediated dark adaptation (RMDA) in persons ≥60 years old with normal maculas as determined by an accepted color fundus photography grading system.

METHODS

This cross-sectional analysis used baseline data from eyes in the Alabama Study on Early Age-Related Macular Degeneration. Eyes at step 1 in the AREDS 9-step grading system were considered normal. Eyes were additionally assessed by spectral domain optical coherence tomography (SD-OCT). Foveal MPOD was estimated via heterochromatic flicker photometry, and RMDA was assessed with a computerized dark adaptometer. The association between RMDA and MPOD was examined via Spearman correlation coefficients adjusted for age.

RESULTS

In 306 eyes from 306 persons (mean age 68.2 years) in normal macular health, MPOD was not associated with RMDA (age-adjusted rank correlation = 0.043, p = 0.45). After 81 eyes with incidental macular findings by SD-OCT evaluation were excluded, the association between MPOD and RMDA remained null (N = 225, age-adjusted r = 0.015, p = 0.82).

CONCLUSION

In a large sample of normal aged eyes, RMDA, a visual function that is rate limited by retinoid availability to photoreceptors across the complex of retinal pigment epithelium, Bruch's membrane, and choriocapillaris, is not related to MPOD in the neurosensory retina.

Macular pigment optical density in a Brazilian sample

Background

To evaluate macular pigment optical density (MPOD) and to identify its determinants in a sample of Brazilian individuals.

Methods

This was a cross-sectional study. One hundred three healthy individuals had both eyes photographed using a Visucam 500 digital fundus camera (Carl Zeiss Meditec, Jena, Germany) in combination with the MPOD module. Four variables were obtained: maximum MPOD, mean MPOD, MPOD volume, and MPOD area. Demographic data and information on lifestyle habits were also collected.

Results

Mean MPOD was 0.14 density unit ± 0.05. MPOD was not influenced by gender, smoking history, or refractive error. MPOD was significantly higher among black individuals than among white and biracial individuals. There was a positive but low correlation between MPOD and age.

Conclusion

This study found MPOD values to be similar to those found in European samples but lower than other studies performed on Asian and Australian samples. This is the first data regarding MPOD in a South American Population.

The Macular Carotenoids Lutein and Zeaxanthin Are Related to Increased Bone Density in Young Healthy Adults

Lutein (L) and zeaxanthin (Z) status can be quantified by measuring their concentrations both in serum and, non-invasively, in retinal tissue. This has resulted in a unique ability to assess their role in a number of tissues ranging from cardiovascular to central nervous system tissue. Recent reports using animal models have suggested yet another role, a developmental increase in bone mass. To test this, we assessed L and Z status in 63 young healthy adults. LZ status was determined by measuring LZ in serum (using HPLC) and retina tissue (measuring macular pigment optical density, MPOD, using customized heterochromatic flicker photometry). Bone density was measured using dual-energy X-ray absorptiometry (DXA). Although serum LZ was generally not related to bone mass, MPOD was significantly related to bone density in the proximal femur and lumbar spine. In general, our results are consistent with carotenoids, specifically LZ, playing a role in optimal bone health.

Correlations Between Macular, Skin, and Serum Carotenoids

Purpose

Ocular and systemic measurement and imaging of the macular carotenoids lutein and zeaxanthin have been employed extensively as potential biomarkers of AMD risk. In this study, we systematically compare dual wavelength retinal autofluorescence imaging (AFI) of macular pigment with skin resonance Raman spectroscopy (RRS) and serum carotenoid levels in a clinic-based population.

Methods

Eighty-eight patients were recruited from retina and general ophthalmology practices from a tertiary referral center and excluded only if they did not have all three modalities tested, had a diagnosis of macular telangiectasia (MacTel) or Stargardt disease, or had poor AFI image quality. Skin, macular, and serum carotenoid levels were measured by RRS, AFI, and HPLC, respectively.

Results

Skin RRS measurements and serum zeaxanthin concentrations correlated most strongly with AFI macular pigment volume under the curve (MPVUC) measurements up to 9° eccentricity relative to MPVUC or rotationally averaged macular pigment optical density (MPOD) measurements at smaller eccentricities. These measurements were reproducible and not significantly affected by cataracts. We also found that these techniques could readily identify subjects taking oral carotenoid-containing supplements.

Conclusions

Larger macular pigment volume AFI and skin RRS measurements are noninvasive, objective, and reliable methods to assess ocular and systemic carotenoid levels. They are an attractive alternative to psychophysical and optical methods that measure MPOD at a limited number of eccentricities. Consequently, skin RRS and MPVUC at 9° are both reasonable biomarkers of macular carotenoid status that could be readily adapted to research and clinical settings.

The Pharmacological Effects of Lutein and Zeaxanthin on Visual Disorders and Cognition Diseases

Lutein (L) and zeaxanthin (Z) are dietary carotenoids derived from dark green leafy vegetables, orange and yellow fruits that form the macular pigment of the human eyes. It was hypothesized that they protect against visual disorders and cognition diseases, such as age-related macular degeneration (AMD), age-related cataract (ARC), cognition diseases, ischemic/hypoxia induced retinopathy, light damage of the retina, retinitis pigmentosa, retinal detachment, uveitis and diabetic retinopathy. The mechanism by which they are involved in the prevention of eye diseases may be due their physical blue light filtration properties and local antioxidant activity. In addition to their protective roles against light-induced oxidative damage, there are increasing evidences that L and Z may also improve normal ocular function by enhancing contrast sensitivity and by reducing glare disability. Surveys about L and Z supplementation have indicated that moderate intakes of L and Z are associated with decreased AMD risk and less visual impairment. Furthermore, this review discusses the appropriate consumption quantities, the consumption safety of L, side effects and future research directions.

The Association between Foveal Morphology and Macular Pigment Spatial Distribution: An Ethnicity Study

Purpose

Macular pigment (MP) spatial distribution varies considerably among individuals. We investigated ethnic variations in MP spatial distribution in relation to foveal architecture.

Methods

We measured MP optical density (MPOD) using heterochromatic flicker photometry (MAP test, City, University of London) in 76 white, 80 South Asian and 70 black volunteers (18 to 39 years). MPOD spatial profiles were classified objectively as exponential, ring-like or central dip, based on deviations away from an exponential fit. Measurements including total retinal thickness (RT), inner retinal layer (IRL), inner and outer plexiform layer (IPL and OPL) thickness, foveal width and foveal pit slope were taken from Spectralis SD-OCT (Heidelberg, Germany) scans.

Results

Integrated MPOD up to 1.8° (MPODint) was higher in South Asian (0.84±0.26) and black (0.84±0.31) than whites (0.63±0.24, P<0.0005). Ethnicity explained around 10% of the variance while gender played no significant role. MPOD profile phenotypes were associated with ethnicity: 58% with ring profiles were South Asian and 43% with dip profiles were black (χ²(4,226) = 13.4, P = 0.009). MPODint was lower in exponential (0.66±0.21) compared to ring-like (0.96±0.26) and central dip (1.00±0.32, P<0.0005) groups. White subjects had thicker IRL at 0° (130±21μm) than South Asian (123±16μm) and blacks (116±14μm; F(2) = 12.4, P<0.0005), with comparable results for IPL (P<0.0005) and OPL (P = 0.03). There was no significant difference in IRL, IPL or OPL (from 0 to 3.8° retinal eccentricity) or foveal width between MP profile groups (P>0.05).

Conclusion

We report a significant difference in the amount and distribution of MP between ethnicities that is not explained by variations in foveal morphology.

Lutein and zeaxanthin supplied by red/orange foods and fruits are more closely associated with macular pigment optical density than those from green vegetables in Spanish subjects

Lutein and zeaxanthin (L+Z) accumulate in the retina. Although vegetables are major contributors to their intake, a stronger association between fruits and macular pigment optical density (MPOD) has been reported. We hypothesized that L+Z intake from fruits would have a stronger association with L+Z status markers (MPOD, serum concentrations) than intake from vegetables or eggs, and that those associations would also differ according to plant foods color. One hundred eight subjects (57 men; age groups, 20-35 and 45-65 years) were enrolled in a cross-sectional study. L+Z intake from fruits, vegetables, and eggs was determined using three 24-hour diet recalls and a country-specific carotenoid database. Vegetables were the major contributors (75%) to L+Z intake, followed by eggs (10%) and fruits (4%). Vegetables supplied 86% and 84% of the LandZ intake, respectively, and fruits supplied 3% and 16%. Green foods supplied 78% and 52% of LandZ, respectively, followed by red/orange (9% and 38%) and white/yellow (14% and 9%). Factorial analysis showed associations in older subjects. The explained variance of the first 2 principal components was 54% considering L+Z intake from fruits, vegetables, and eggs, and 55% considering L+Z intake from plant foods grouped by color. Macular pigment optical density is related to L+Z intake from fruits (0.264, P=.003) and is independent of that from vegetables and eggs. It is related to L+Z intake from red/orange foods (0.320, P=.000) and the serum concentrations to that from green foods (0.222, P=.11). Although vegetables and green foods of plant origin are the major contributors to L+Z intake, red/orange foods and fruits have the strongest relationship to MPOD in study participants (45-65 years of age).

Serum and retinal responses to three different doses of macular carotenoids over 12 weeks of supplementation

The macular carotenoids lutein (L), zeaxanthin (Z), and mesozeaxanthin (MZ) have been shown to have neuroprotective and visual performance benefits once deposited in retinal tissues. The purpose of this 12-week trial was to determine biweekly the absorption kinetics, efficiency of retinal deposition, and effects on the spatial profile of macular pigment for three levels of L + Z + MZ supplement. This study was a double-blind, placebo-controlled 12-week trial. Twenty-eight healthy subjects, aged 18-25 yrs participated. Subjects were randomly assigned to one of four daily supplementation groups: placebo (safflower oil; n = 5), 7.44 mg total macular carotenoid (n = 7), 13.13 mg total macular carotenoid (n = 8), and 27.03 (n = 8) mg total macular carotenoid. Ratios of the three carotenoids were virtually identical for the three levels of supplement (83% L, 10% Z, 7% MZ). At baseline and every two weeks thereafter over the 12-week study period, a fasting blood draw was conducted and, via heterochromatic flicker photometry, spatial profiles of macular pigment optical density (MPOD) were determined. Compared to placebo, serum concentrations of both L and total Z, for each of the supplement levels, were found to increase significantly from baseline after two weeks of daily ingestion (p < 0.001). Likewise, MPOD increased significantly in all treatment groups (p < 0.001) compared to placebo. Serum responses (L, Z, and L + Z) were linearly related to dose (p < 0.001 for all), but not to retinal response. L: Z serum response ratios decreased exponentially with increases in dose (p = 0.008). The ratio of MPOD change: total serum response was found to be highest for the 13.13 mg level of supplement (p = 0.021), followed by 27.03- and 7.44-mg doses. The very center of the spatial profile of MPOD increased in a fashion commensurate with dose level. Although L serum responses increased with dose, the slope of increase was shallower than for Z. Given the higher levels of L in the supplements, this is suggestive of a compressed response with relatively high doses of L. Although all three doses significantly augmented MPOD, the 13.13 mg/day L + Z supplement level was the most efficient in doing so. The data regarding efficiency may inform recommendations regarding macular carotenoid supplementation for age-related macular degeneration. Lastly (although not statistically significant), the shift toward a more pronounced central peak in the spatial profile of MPOD in all treatment groups suggests that central retinal deposition of Z and MZ was efficient and can be seen after a short period of supplementation, especially with higher (e.g. 27.03 mg) daily doses of macular carotenoids. ISRCTN trial registration number: ISRCTN54990825.

Comparison of Fundus Autofluorescence and Minimum-Motion Measurements of Macular Pigment Distribution Profiles Derived from Identical Retinal Areas

The optical density of macular pigment was measured at twelve retinal locations in ten subjects by minimum motion photometry, comparing 460 nm with 580 nm or 550 nm. Fundus autofluorescence images were obtained for the same subjects with a scanning laser ophthalmoscope. Optical density was computed from mean calibrated grey-scale values for a central circular field and for annular segments, identical to areas tested psychophysically, and for complete annuli. Psychophysical assessments of optical density were similar irrespective of whether 550 nm or 580 nm was used. Optical density values derived psychophysically showed a linear correlation with assessments based on identical sampled areas of annular segments (slope = 0.98, r2 = 0.97) or complete annuli (slope = 0.89, r2 = 0.96) in autofluorescence images.

Individual Colorimetric Observer Model

This study proposes a vision model for individual colorimetric observers. The proposed model can be beneficial in many color-critical applications such as color grading and soft proofing to assess ranges of color matches instead of a single average match. We extended the CIE 2006 physiological observer by adding eight additional physiological parameters to model individual color-normal observers. These eight parameters control lens pigment density, macular pigment density, optical densities of L-, M-, and S-cone photopigments, and λmax shifts of L-, M-, and S-cone photopigments. By identifying the variability of each physiological parameter, the model can simulate color matching functions among color-normal populations using Monte Carlo simulation. The variabilities of the eight parameters were identified through two steps. In the first step, extensive reviews of past studies were performed for each of the eight physiological parameters. In the second step, the obtained variabilities were scaled to fit a color matching dataset. The model was validated using three different datasets: traditional color matching, applied color matching, and Rayleigh matches.

Macular pigment optical density in a healthy Chinese population

PURPOSE

To measure the macular pigment optical density (MPOD) values in a healthy Chinese population using the one-wavelength reflectometry method and to investigate the relationships of MPOD with age, sex, body mass index (BMI), smoking and lens opacities.

METHODS

A total of 441 healthy participants, aged 3-81 years old (242 male and 199 female subjects), were enrolled in this study. Demographic and lifestyle data were recorded based on physical examinations and questionnaires. Lens opacities were measured according to the Lens Opacities Classification System III (LOCS III). MPOD values were measured at 7° of eccentricity, using the one-wavelength reflectometry method (Visucam 200; Carl Zeiss Meditec). MPOD values were reported in parameters including 'max' and 'mean' optical density (OD). The original MPOD values without automated correction were used for analysis.

RESULTS

The average values were 0.303 ± 0.097 d.u. (initials of density units) for the max OD and 0.109 ± 0.031 d.u. for the mean OD. A significant inverse relationship was found between age and MPOD (for max OD, β = -0.716, p < 0.001; for mean OD, β = -0.669, p < 0.001). Participants with no lens opacities had higher MPOD values than those with moderate lens opacities (p < 0.001). The MPOD values were not associated with sex, BMI or smoking status.

CONCLUSION

MPOD within 7° of eccentricity, as measured by one-wavelength reflectometry, was found to decrease with increasing age in a healthy Chinese population, and lens opacities had an impact on these measurements. These results provide a reference value for future studies in the Chinese population.

Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children

Macular pigment optical density (MPOD)-assessed using customized heterochromatic flicker photometry (cHFP)-is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7-10-year-olds (n = 66) underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46) with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59-session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27). There was no significant difference in the MPOD of boys vs. girls (p = 0.56). There was a significant correlation between sessions (Y = 0.52x + 0.31; R² = 0.29, p ≤ 0.005), with a reliability of 0.70 (Cronbach's α). Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R² = 0.32, p < 0.005), with a reliability of 0.72 (Cronbach's α). In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood.

Association of macular pigment optical density with serum concentration of oxidized low-density lipoprotein in healthy adults

PURPOSE

To analyze the association between macular pigment optical density (MPOD), which reflects lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) in the macula, and background characteristics.

METHODS

Fifty-five healthy adult volunteers were analyzed. Macular pigment optical density was measured using a heterochromatic flicker photometry technique, and serum concentrations of carotenoids and lipoproteins were by high-performance liquid chromatography and enzyme-linked immunosorbent assay, respectively. Dietary intake of nutrient was determined by a validated self-administered questionnaire on ingestion frequency.

RESULTS

Macular pigment optical density was positively correlated with serum concentrations of L and Z and dietary L intake and inversely correlated with serum oxidized low-density lipoprotein (LDL). Although MPOD decreased with age (95% confidence interval, -0.011 to -0.002; correlation coefficient, -0.269; P = 0.007), serum L/Z and dietary L intake did not. In contrast, serum oxidized LDL was positively correlated with age (95% confidence interval, 0.69-2.34; correlation coefficient, 0.333; P = 0.0004). After adjusting for age, sex, and oxidized LDL, serum L was positively correlated with MPOD (95% confidence interval, 0.88-1.69; P = 0.000001). After adjusting for age, sex, and serum L, serum oxidized LDL was inversely correlated with MPOD (95% confidence interval, -0.002 to -0.0004; P = 0.006).

CONCLUSION

Macular pigment optical density was inversely correlated with serum oxidized LDL. Further study to know the impact of oxidized LDL on MPOD may be warranted.

Macular xanthophylls, lipoprotein-related genes, and age-related macular degeneration

Plant-based macular xanthophylls (MXs; lutein and zeaxanthin) and the lutein metabolite meso-zeaxanthin are the major constituents of macular pigment, a compound concentrated in retinal areas that are responsible for fine-feature visual sensation. There is an unmet need to examine the genetics of factors influencing regulatory mechanisms and metabolic fates of these 3 MXs because they are linked to processes implicated in the pathogenesis of age-related macular degeneration (AMD). In this work we provide an overview of evidence supporting a molecular basis for AMD-MX associations as they may relate to DNA sequence variation in AMD- and lipoprotein-related genes. We recognize a number of emerging research opportunities, barriers, knowledge gaps, and tools offering promise for meaningful investigation and inference in the field. Overviews on AMD- and high-density lipoprotein (HDL)-related genes encoding receptors, transporters, and enzymes affecting or affected by MXs are followed with information on localization of products from these genes to retinal cell types manifesting AMD-related pathophysiology. Evidence on the relation of each gene or gene product with retinal MX response to nutrient intake is discussed. This information is followed by a review of results from mechanistic studies testing gene-disease relations. We then present findings on relations of AMD with DNA sequence variants in MX-associated genes. Our conclusion is that AMD-associated DNA variants that influence the actions and metabolic fates of HDL system constituents should be examined further for concomitant influence on MX absorption, retinal tissue responses to MX intake, and the capacity to modify MX-associated factors and processes implicated in AMD pathogenesis.

Changes in spatial extent and peak double optical density of human macular pigment with age

The purpose of the present work was to estimate the changes in spatial distribution and optical density of macular pigment (MP) with age. A fundus imaging system with high spatial and spectral resolution was adapted to form an indirect ophthalmoscope. The double optical density at 490 nm of the MP as a function of the location in the retina was obtained for 33 healthy subjects (ages: 21-60 years). There was an increase in spatial extent and decrease in double optical density with age. Furthermore, the spatial distribution of MP showed central areas with irregular shapes and a tendency toward asymmetry.

Color discrimination in individuals with light and dark irides: an evaluation of the effects of intraocular straylight and retinal illumination

To investigate the effect of induced intraocular straylight on the Farnsworth-Munsell 100-hue test performance in individuals with light and dark irides, 28 young subjects were tested both with and without a quantified light-scattering filter. The filter produced a significant increase in the total error scores (p<0.05), but no significant correlation was found between the level of straylight and error score (p>0.05). The development of a tritan-like defect in the dark-eyed participants can be attributed to the effect of light attenuation caused by filter absorption, which markedly affects S-cone mediated color discrimination. The combined effect of higher short-wavelength absorption of melanin and macular pigment in the dark eyes may be involved.

The association between dark adaptation and macular pigment optical density in healthy subjects

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.

The use of heterochromatic flicker photometry to determine macular pigment optical density in a healthy Australian population

PURPOSE

To establish the normal macular pigment density (MPOD) in a healthy adult Australian sample using heterochromatic flicker photometry (HFP).

METHODS

Macular pigment density was measured using heterochromatic flicker photometry in a total of 201 subjects ranging in age from 21 to 84 years with healthy macula. Fifty-seven of the healthy subjects also completed a food-frequency dietary questionnaire. Best-corrected visual acuity (BCVA) was measured using logMAR, chart and macular morphological profiles were assessed using high-resolution integrated Fourier-domain optical coherence tomography (OCT).

RESULTS

The average MPOD value was 0.41 ± 0.20 (range 0.07-0.79). There was no statistically significant difference between values in the left and right eye, with good interocular agreement (0.41 vs 0.40, r = 0.893, p < 0.01). Age significantly predicted MPOD score (R (2) = 0.07, p < 0.05). A subgroup analysis of patients who completed the dietary questionnaire revealed a close correlation between higher diet scores and higher MPOD (r = 0.720 p = 0.031). There was no effect of smoking, gender, or iris colour on MPOD values. There was no significant correlation between BCVA, macular OCT profiles, and MPOD.

CONCLUSION

Given that MPOD values are potentially affected by geographical variation, we have determined a mean MPOD value for healthy subjects in a population south of the equator, providing a reference point for future studies on Caucasian samples.

The macular pigment optical density spatial profile and increasing age

PURPOSE

To investigate the relationship between the central spatial profile of macular pigment optical density (MPOD) and increasing age in normal eyes.

METHODS

Ninety-eight individuals (aged 19-71 years) with good visual acuity, free from ocular disease, and with clear ocular media participated. MPOD was measured at 0.25, 0.50, 1.00, and 1.75° eccentricity from the foveal centre using a heterochromatic flicker photometry based densitometer instrument.

RESULTS

Linear regression analysis revealed that there was no statistically significant association between MPOD and increasing age for the group as a whole at 0.25, 0.50, and 1.00° eccentricity (p > 0.05 for all eccentricities). There was a small but statistically significant positive association between increasing age and MPOD at 1.75° eccentricity (p = 0.020), but age only accounted for 6 % of the variation in MPOD values. Fifteen percent of all participants had a non-exponential MPOD spatial profile.

CONCLUSION

There was no statistically significant relationship between MPOD and increasing age for three of the four locations measured. A significant proportion of individuals show an atypical MPOD spatial profile, indicating that studies on MPOD should ideally report information on the MPOD spatial profile rather than estimates from only one retinal location.

Inverse relationship between macular pigment optical density and axial length in Chinese subjects with myopia

BACKGROUND

Macular pigment (MP) has been the focus of much attention in recent years, due to its protective effect against macular degenerations. In this study, we investigated the association between macular pigment optical density (MPOD) and axial length (AL) in Chinese subjects with myopia.

METHODS

In total, 173 myopes (mean spherical equivalent [MSE] ≤-1.00D) were recruited for this prospective observational study. MPOD was measured in both eyes of each subject using a macular metrics densitometer. AL was measured in eyes using an IOL-Master. A raw coefficient of correlation analysis and a partial correlation analysis were used to investigate the relationship between MPOD and AL.

RESULTS

The age of the subjects ranged from 18 to 67 years. The overall mean MPOD for the cohort was 0.412 ± 0.119 (range, 0.105-0.812). The mean AL was 25.18 ± 1.08 mm (range, 23.14-28.19 mm). Using a raw coefficient of correlation, a significant inverse correlation was found between MPOD and AL (r= -0.134, p=0.012). When using a partial correlation analysis to eliminate the impact of covariant, a significant inverse correlation was also found between MPOD and AL (r= -0.142, p=0.008). Furthermore, when AL was divided into two groups: AL>26 mm and AL ≤ 26 mm, a significant inverse correlation was observed between MPOD and AL in the former (r= -0.253, p=0.029), but no significant relationship was observed between these in the latter (r=0.104, p=0.067).

CONCLUSIONS

MPOD correlated inversely with AL in this sample of Chinese subjects with myopia.

The putative role of lutein and zeaxanthin as protective agents against age-related macular degeneration: promise of molecular genetics for guiding mechanistic and translational research in the field

Age-related macular degeneration (AMD) is the primary cause of vision loss in elderly people of western European ancestry. Genetic, dietary, and environmental factors affect tissue concentrations of macular xanthophylls (MXs) within retinal cell types manifesting AMD pathology. In this article we review the history and state of science on the putative role of the MXs (lutein, zeaxanthin, and meso-zeaxanthin) in AMD and report findings on AMD-associated genes encoding enzymes, transporters, ligands, and receptors affecting or affected by MXs. We then use this context to discuss emerging research opportunities that offer promise for meaningful investigation and inference in the field.

The heritability of macular response to supplemental lutein and zeaxanthin: a classic twin study

PURPOSE

Antioxidant supplements may reduce age-related macular degeneration (AMD) progression. The macular carotenoids are of particular interest because of their biochemical, optical, and anatomic properties. This classic twin study was designed to determine the heritability of macular pigment (MP) augmentation in response to supplemental lutein (L) and zeaxanthin (Z).

METHODS

A total of 322 healthy female twin volunteers, aged 16-50 years (mean 40 ± 8.7) was enrolled in a prospective, nonrandomized supplement study. Macular pigment optical density (MPOD) measurements using two techniques (2-wavelength fundus autofluorescence [AF] and heterochromatic flicker photometry [HFP]), and serum concentrations of L and Z, were recorded at baseline, and at 3 and 6 months following daily supplementation with 18 mg L and 2.4 mg Z for a study period of 6 months.

RESULTS

At baseline, mean MPOD was 0.44 density units (SD 0.21, range 0.04-1.25) using HFP, and 0.41 density units (SD 0.15) using AF. Serum L and Z levels were raised significantly from baseline following 3 months' supplementation (mean increase 223% and 633%, respectively, P < 0.0001 for both), with no MPOD increase. After 6 months' supplementation, a small increase in MPOD was seen (mean increase 0.025 ± 0.16, P = 0.02, using HFP). Subdivision of baseline MPOD into quartiles revealed that baseline levels made no difference to the treatment effect. Genetic factors explained 27% (95% confidence interval [CI] 7-45) of the variation in MPOD response. Distribution profiles of macular pigment did not change in response to supplementation.

CONCLUSIONS

MPOD response to supplemental L and Z for a period of 6 months was small (an increase over baseline of 5.7% and 3.7%, measured using HFP and AF, respectively), and was moderately heritable. Further study is indicated to investigate the functional and clinical impact of supplementation with the macular carotenoids.

Heritability of the spatial distribution and peak density of macular pigment: a classical twin study

PURPOSE

To elucidate the heritability of peak density and spatial width of macular pigment (MP) using a Classical Twin Study.

METHODS

Fundus autofluorescence images were obtained at 488 nm from 86 subjects or 43 twin pairs (21 monozygotic (MZ) and 22 dizygotic (DZ)) (27 male, 59 female) aged from 55 to 76 years (mean 62.2 ± 5.3 years). The relative topographic distribution of MP was measured using a grey scale of intensity (0-255 units) in a 7° eccentricity around the fovea. Relative peak MP density (rPMPD) and relative spatial distribution of MP (rSDMP) were used as the main outcome measure in the statistical analysis.

RESULTS

A significantly higher correlation was found within MZ pairs as compared with that within DZ pairs for rPMPD, (r=0.99, 95% confidence interval (95% CI) 0.93 to 1.00) and 0.22, 95% CI -0.34 to 0.71), respectively, suggesting strong heritability of this trait. When rSDMP was compared, there was no significant difference between the correlations within MZ pairs (r=0.48, 95% CI -0.02 to 0.83) and DZ pairs (r=0.63, 95% CI 0.32 to 0.83), thus rSDMP is unlikely to have a considerable heritable component. In addition, there was no difference between any MP parameter when normal maculae were compared with early age-related macular degeneration (AMD) (rPMPD 0.36 vs 0.34, t=1.18 P=0.243, rSDMP 1.75 vs 1.75, t=0.028 P=0.977).

CONCLUSIONS

rPMPD is a strongly heritable trait whereas rSDMP has minimal genetic influence and a greater influence by environmental factors. The presence of macular changes associated with early AMD did not appear to influence any of these pigment parameters.

An evaluation of a novel instrument for measuring macular pigment optical density: the MPS 9000

PURPOSE

Of the antioxidants found in the human retina, only the macular carotenoid quantities can be estimated noninvasively (albeit in a collective fashion), thus facilitating study of their role in that tissue. The aim of this study was to evaluate concordance between macular pigment optical density (MPOD) values recorded on a commercially available instrument, the MPS 9000, with those of an already validated heterochromatic flicker photometry instrument. Also, we assessed and compared test-retest variability for each instrument.

METHODS

Macular pigment optical density at 0.5 retinal eccentricity was measured using two different heterochromatic flicker photometers, the MPS 9000 and the Macular Densitometer(TM), in 39 healthy subjects. Test-retest variability was evaluated separately for each instrument by taking three readings over a 1-week period in 25 subjects.

RESULTS

There was a moderate positive correlation for MPOD at 0.5° of retinal eccentricity between the MPS 9000 and the Macular Densitometer described by the linear equation y = 0.763x + 0.172 (r = 0.68, p < 0.001, r(2) = 0.46); however, a paired-samples t-test showed a significant difference in terms of mean values, with a bias of lower MPOD values being yielded by the MPS 9000 (t = -4.103, p < 0.001). Bland-Altman analysis indicated only moderate agreement between the two instruments, reflected in 95% limits of agreement of 0.1 ± 0.27. Inter-sessional repeatability, expressed as a coefficient of repeatability, ranged from 0.18 to 0.21 [mean (±SD): 0.19 (0.02)] for the MPS 9000 and from 0.11 to 0.12 [mean (±SD): 0.12 (0.01)] for the Macular Densitometer.

CONCLUSION

The results demonstrate that the MPS 9000 consistently yields MPOD readings, which are lower than that found with the Macular Densitometer, and exhibits substantial test-retest variability.

The effect of lutein- and zeaxanthin-rich foods v. supplements on macular pigment level and serological markers of endothelial activation, inflammation and oxidation: pilot studies in healthy volunteers

The aim of the present study was to compare the effect of lutein- and zeaxanthin-rich foods and supplements on macular pigment level (MPL) and serological markers of endothelial activation, inflammation and oxidation in healthy volunteers. We conducted two 8-week intervention studies. Study 1 (n 52) subjects were randomised to receive either carrot juice (a carotene-rich food) or spinach powder (a lutein- and zeaxanthin-rich food) for 8 weeks. Study 2 subjects (n 75) received supplements containing lutein and zeaxanthin, β-carotene, or placebo for 8 weeks in a randomised, double-blind, placebo-controlled trial. MPL, serum concentrations of lipid-soluble antioxidants, inter-cellular adhesion molecule 1, vascular cell adhesion molecule 1, C-reactive protein and F2-isoprostane levels were assessed at baseline and post-intervention in both studies. In these intervention studies, no effects on MPL or markers of endothelial activation, inflammation or oxidation were observed. However, the change in serum lutein and zeaxanthin was associated or tended to be associated with the change in MPL in those receiving lutein- and zeaxanthin-rich foods (lutein r 0·40, P = 0·05; zeaxanthin r 0·30, P = 0·14) or the lutein and zeaxanthin supplement (lutein r 0·43, P = 0·03; zeaxanthin r 0·22, P = 0·28). In both studies, the change in MPL was associated with baseline MPL (food study r − 0·54, P < 0·001; supplement study r − 0·40, P < 0·001). We conclude that this 8-week supplementation with lutein and zeaxanthin, whether as foods or as supplements, had no significant effect on MPL or serological markers of endothelial activation, inflammation and oxidation in healthy volunteers, but may improve MPL in the highest serum responders and in those with initially low MPL.

Multispectral retinal image analysis: a novel non-invasive tool for retinal imaging

PURPOSE

To develop a non-invasive method for quantification of blood and pigment distributions across the posterior pole of the fundus from multispectral images using a computer-generated reflectance model of the fundus.

METHODS

A computer model was developed to simulate light interaction with the fundus at different wavelengths. The distribution of macular pigment (MP) and retinal haemoglobins in the fundus was obtained by comparing the model predictions with multispectral image data at each pixel. Fundus images were acquired from 16 healthy subjects from various ethnic backgrounds and parametric maps showing the distribution of MP and of retinal haemoglobins throughout the posterior pole were computed.

RESULTS

The relative distributions of MP and retinal haemoglobins in the subjects were successfully derived from multispectral images acquired at wavelengths 507, 525, 552, 585, 596, and 611 nm, providing certain conditions were met and eye movement between exposures was minimal. Recovery of other fundus pigments was not feasible and further development of the imaging technique and refinement of the software are necessary to understand the full potential of multispectral retinal image analysis.

CONCLUSION

The distributions of MP and retinal haemoglobins obtained in this preliminary investigation are in good agreement with published data on normal subjects. The ongoing development of the imaging system should allow for absolute parameter values to be computed. A further study will investigate subjects with known pathologies to determine the effectiveness of the method as a screening and diagnostic tool.

The association between macular pigment optical density and CFH, ARMS2, C2/BF, and C3 genotype

Age-related macular degeneration (AMD) is the most common cause of blindness in older people in developed countries, and risk for this condition may be classified as genetic or environmental, with an interaction between such factors predisposing to this disease. This study investigated the relationship between AMD risk genes, macular pigment optical density (MPOD), which may protect against AMD, and serum concentrations of the macular carotenoids, lutein (L) and zeaxanthin (Z). This was a cross-sectional study of 302 healthy adult subjects. Dietary intake of L and Z was assessed by food frequency questionnaire, and MPOD was measured by customized heterochromatic flicker photometry. We also calculated MPOD Area as the area of MP under the spatial profile curve, to reflect MP across the macula. Serum L and Z were measured by HPLC. Genotyping of tag SNPs in the genes CFH, ARMS2, C3, C2 and BF was undertaken with multiplex polymerase chain reaction (PCR) and primer extension methodology (ABI Snapshot, ABI Warrington UK) on DNA extracted from peripheral blood. The mean ± SD (range) age of the subjects in this study was 48 ± 11 (21-66) years. There was a statistically significant association between CFH genotype and family history of AMD, with subjects having two non-risk CFH haplotypes (n = 35), or one non-risk and one protective CFH haplotype (n = 33), being significantly more likely to have a negative family history of AMD (Pearson Chi square: p = 0.001). There was no significant association between the AMD risk genes investigated and either MPOD (One way ANOVA: p > 0.05) or serum concentrations of L or Z (One way ANOVA: p > 0.05, for both). Subjects who were homozygous for risk alleles of both CFH and ARMS2 (n = 4) had significantly lower MPOD at 0.5° and 1° retinal eccentricity (Independent samples t test: p < 0.05) and lower MPOD Area which approached statistical significance (Independent samples t test: p = 0.058), compared to other subjects (n = 291). In conclusion, this study did not detect an association between individual AMD risk genotypes and the putatively protective MP, or serum concentrations of its constituent carotenoids. However, the combination of homozygous risk alleles at both CFH and ARMS2 loci was associated with significantly lower MPOD centrally, despite comparable serum concentrations of the macular carotenoids. These findings suggest that the maculae of subjects at very high genetic risk of AMD represent a hostile environment for accumulation and/or stabilization of MP.

Measuring macular pigment optical density in vivo: a review of techniques

BACKGROUND

Macular pigment has been the focus of much attention in recent years, as a potential modifiable risk factor for age-related macular degeneration. This interest has been heightened by the ability to measure macular pigment optical density (MPOD) in vivo.

METHOD

A systematic literature search was undertaken to identify all available papers that have used in vivo MPOD techniques. The papers were reviewed, and all relevant information was incorporated into this article.

RESULTS

Measurement of MPOD is achievable with a wide range of techniques, which are typically categorized into one of two groups: psychophysical (requiring a response from the subject) or objective (requiring minimal input from the subject). The psychophysical methods include heterochromatic flicker photometry and minimum motion photometry. The objective methods include fundus reflectometry, fundus autofluorescence, resonance Raman spectroscopy and visual evoked potentials. Even within the individual techniques, there is often much variation in how data is obtained and processed.

CONCLUSION

This review comprehensively details the procedure, instrumentation, assumptions, validity and reliability of each MPOD measurement technique currently available, along with their respective advantages and disadvantages. This leads us to conclude that development of a commercial instrument, based on fundus reflectometry or fundus autofluorescence, would be beneficial to macular pigment research and would support MPOD screening in a clinical setting.

Macular pigment optical density measurements: evaluation of a device using heterochromatic flicker photometry

PURPOSE

Accurate assessment of the amount of macular pigment (MPOD) is necessary to investigate the role of carotenoids and their assumed protective functions. High repeatability and reliability are important to monitor patients in studies investigating the influence of diet and supplements on MPOD. We evaluated the Macuscope (Macuvision Europe Ltd., Lapworth, Solihull, UK), a recently introduced device for measuring MPOD using the technique of heterochromatic flicker photometry (HFP). We determined agreement with another HFP device (QuantifEye; MPS 9000 series: Tinsley Precision Instruments Ltd., Croydon, Essex, UK) and a fundus reflectance method.

METHODS

The right eyes of 23 healthy subjects (mean age 33.9 ± 15.1 years) were measured. We determined agreement with QuantifEye and correlation with a fundus reflectance method. Repeatability of QuantifEye was assessed in 20 other healthy subjects (mean age 32.1 ± 7.3 years). Repeatability was also compared with measurements by a fundus reflectance method in 10 subjects.

RESULTS

We found low agreement between test and retest measurements with Macuscope. The average difference and the limits of agreement were -0.041 ± 0.32. We found high agreement between test and retest measurements of QuantifEye (-0.02 ± 0.18) and the fundus reflectance method (-0.04 ± 0.18). MPOD data obtained by Macuscope and QuantifEye showed poor agreement: -0.017 ± 0.44. For Macuscope and the fundus reflectance method, the correlation coefficient was r = 0.05 (P = 0.83). A significant correlation of r = 0.87 (P<0.001) was found between QuantifEye and the fundus reflectance method.

CONCLUSIONS

Because repeatability of Macuscope measurements was low (ie, wide limits of agreement) and MPOD values correlated poorly with the fundus reflectance method, and agreed poorly with QuantifEye, the tested Macuscope protocol seems less suitable for studying MPOD.

The value of measurement of macular carotenoid pigment optical densities and distributions in age-related macular degeneration and other retinal disorders

There is increasing recognition that the optical and antioxidant properties of the xanthophyll carotenoids lutein and zeaxanthin play an important role in maintaining the health and function of the human macula. In this review article, we assess the value of non-invasive quantification of macular pigment levels and distributions to identify individuals potentially at risk for visual disability or catastrophic vision loss from age-related macular degeneration, and we consider the strengths and weaknesses of the diverse measurement methods currently available.

A new desktop instrument for measuring macular pigment optical density based on a novel technique for setting flicker thresholds

A rapid portable technique for estimating macular pigment optical density (MPOD) in large populations is described. The new instrument utilises a novel method for setting flicker thresholds which is undemanding for naïve and elderly observers and easily operated by a non-technical person. The method has good repeatability (r = 0.97) and the data are comparable with an optical method based on retinal reflectometry (r = 0.78). MPOD spatial profiles are presented for seven normal observers and these are well described (r = 0.99) by a decaying exponential function consistent with previous reports. MPOD values are presented from 5581 (2435 females and 3146 males) individuals measured in 48 optometric practices. The mean MPOD of this population was 0.33 (S.D. +/- 0.187) which is similar to previous large scale studies of MP.

The relationship of macular pigment optical density to serum lutein in retinitis pigmentosa

PURPOSE

To determine whether macular pigment optical density (MPOD) is related to serum lutein or serum zeaxanthin in patients with retinitis pigmentosa.

METHODS

The authors measured MPOD with heterochromatic flicker photometry, serum lutein and serum zeaxanthin by high performance liquid chromatography, and central foveal retinal thickness by optical coherence tomography (OCT) in 176 patients (age range, 18-68 years) with typical forms of retinitis pigmentosa; 37 (21%) of these patients had cystoid macular edema (CME) by OCT. The authors performed multiple regression analysis with MPOD as the dependent variable and with log(e) serum lutein and log(e) serum zeaxanthin as independent variables adjusting for age, sex, iris color, central foveal retinal thickness, and, in some analyses, serum total cholesterol.

RESULTS

MPOD increased with increasing serum lutein (P = 0.0017) and decreased with increasing serum total cholesterol (P = 0.0025) but was unrelated to serum zeaxanthin. MPOD was higher in patients with brown irides than in patients with lighter irides (P = 0.014) and was nonmonotonically related to central foveal retinal thickness (P < 0.0001), being lower in eyes with more photoreceptor cell loss and in eyes with moderate to marked CME.

CONCLUSIONS

MPOD is independently related to serum lutein, serum total cholesterol, iris color, and central foveal retinal thickness in patients with retinitis pigmentosa.

Women's Health Initiative diet intervention did not increase macular pigment optical density in an ancillary study of a subsample of the Women's Health Initiative

In this study, we examined the impact of long-term (>8 y), low-fat, high-fruit and -vegetable diets on levels of lutein and zeaxanthin in the macula of the retina, as indicated by the OD of macular pigment. Macular pigment OD, measured by heterochromatic flicker photometry, was compared in women aged 60-87 y, who, 7-18 mo earlier (median 12 mo), had been in the dietary modification intervention (n = 158) or comparison (n = 236) groups of the Women's Health Initiative (WHI) at the Madison, WI site for a mean of 8.5 y. Women in the intervention group ate more fruits and vegetables (mean +/- SEM) (6.1 +/- 0.2 vs. 4.6 +/- 0.2 servings/d; P < 0.0001) and had higher intakes of lutein and zeaxanthin from foods and supplements (2.7 +/- 0.2 vs. 2.1 +/- 0.1 mg/d; P = 0.0003) than the comparison group. However, macular pigment density did not differ between the intervention (0.36 +/- 0.02 OD units) and comparison (0.35 +/- 0.01 OD units) groups. It tended to be higher (11%; P = 0.11) in women consuming lutein and zeaxanthin in the highest compared with the lowest quintile (median 6.4 vs. 1.1 mg/d). The increase in fruit and vegetable intake among dietary modification participants of this WHI subsample was not of sufficient magnitude to alter the mean density of retinal carotenoids, given other existing dietary conditions in this sample.

[The macular pigment: short- and intermediate-term changes of macular pigment optical density following supplementation with lutein and zeaxanthin and co-antioxidants. The LUNA Study]

BACKGROUND

How long do the elevated concentrations of macular pigment persist after stopping supplementation with lutein and zeaxanthin?

METHODS

One hundred eight (108) probands with and without age-related macular degeneration (68 female, 40 male, age 51-87 years) received a supplement containing 12 mg lutein and 1 mg zeaxanthin once per day (Ocuvite lutein) for 6 months. Analysis of macular pigment optical density (MPOD) was performed during the period of supplementation and again 3, 6, and 9 months following discontinuation of the supplement. A control group of 28 subjects received no dietary supplement.

RESULTS

At baseline, the mean MPOD at 0.5 degrees was 0.50 in the supplemented group. Following supplementation, values rose, and 3 months after discontinuation of supplementation the highest levels of MPOD0.5 degrees (0.59 ODU) were detected (increase of +0.1 ODU, (p<0.001). Six months after supplement discontinuation, a slight decrease of mean MPOD0.5 degrees appeared (to 0.54 ODU), followed again by a slight increase 3 months later (to 0.57 ODU). An increment of MPOD0.5 degrees in the control group was not significant (0.03 ODU, p=0.15).

DISCUSSION

Supplementation of lutein and zeaxanthin leads to an increase of MPOD0.5 degrees . This effect outlasts the duration of intake, and 9 months after supplementation was stopped, the mean MPOD0.5 degrees was still elevated compared with baseline levels. A longer follow-up subsequent to stopping supplementation might clarify whether the values decrease over time or whether a plateau of elevated MPOD levels is reached. High doses of lutein and zeaxanthin seem to be necessary to increase macular pigment density in the retina; afterwards, the amount of carotenoids needed to maintain high concentrations seems to be covered by daily food.

Long-term plant stanol and sterol ester-enriched functional food consumption, serum lutein/zeaxanthin concentration and macular pigment optical density

Observational epidemiological studies have shown that low carotenoid intake and/or low carotenoid blood levels increase the risk of degenerative diseases like age-related macular degeneration. Functional foods enriched with plant sterol or stanol esters may lower serum concentrations of fat-soluble carotenoids. Theoretically, as a result the macular pigment optical density (MPOD), a marker for eye health, may change. We carried out a double-blind placebo-controlled human intervention trial with a duration of 18 months to evaluate the possible effects of plant stanol and sterol esters on serum lutein/zeaxanthin concentration in relation to the MPOD. Forty-seven subjects were randomly assigned to one of the three treatment groups: margarine without added plant sterols or stanols, plant sterol-enriched margarine, or plant stanol-enriched margarine. Serum cholesterol and lutein/zeaxanthine concentrations and the MPOD were evaluated at baseline and at study end. Changes in lipid-adjusted serum lutein/zeaxanthine concentrations between baseline and study end differed significantly between the three groups (P = 0.001). We found no differences in the MPOD between the three treatment groups, despite the differences in both absolute and cholesterol-standardized serum lutein/zeaxanthine concentrations. This shows that the observed reduction in serum carotenoid concentrations during 18 months consumption of these functional foods does not affect MPOD.