Macular pigment and age related macular degeneration

Association between various types of obesity and macular pigment optical density

PURPOSE

To elucidate the association between macular pigment optical density (MPOD) and various types of obesity in the South-Indian population.

PATIENTS AND METHODS

In total, 300 eyes of 161 healthy volunteers of South-Indian origin were studied. MPOD was measured psychophysically at 0.25°, 0.50°, 1.00°, and 1.75° eccentricities from fovea. Anthropometric measurements included waist circumference (WC) and waist-to-hip ratio (WHR) and body mass index (BMI). Using the WHO Expert Consultation guidelines, obesity was defined based on BMI alone (BMI ≥ 23 kg/m(2)), based on WC alone (WC ≥ 90 cm for men and ≥ 80 cm for women), and based on WHR alone (≥ 0.90 for men and ≥ 0.85 for women). Isolated generalized obesity was defined as increased BMI and normal WC. Isolated abdominal obesity was defined as increased WC and normal BMI. Combined obesity was defined as increased BMI and increased WC.

RESULTS

Mean MPOD at all eccentricities was not significantly different between men and women. Mean MPOD values did not significantly differ in various types of obesity, when compared with the normal subjects. On subgroup analysis, in age group ≥ 60 years, mean MPOD values were significantly higher in subjects with obesity based on BMI (0.61 vs 0.41, P=0.036), obesity based on WHR (0.67 vs 0.41, P=0.007), and isolated generalized obesity (0.66 vs 0.41, P=0.045) in comparison with normal subjects at 0.25° eccentricity.

CONCLUSION

We found lack of an association between MPOD and obesity in the South-Indian population. A similar finding was also noted on age group- and gender-wise analyses.

Snapshot hyperspectral retinal camera with the Image Mapping Spectrometer (IMS)

We present a snapshot hyperspectral retinal camera with the Image Mapping Spectrometer (IMS) for eye imaging applications. The resulting system is capable of simultaneously acquiring 48 spectral channel images in the range 470 nm-650 nm with frame rate at 5.2 fps. The spatial sampling of each measured spectral scene is 350 × 350 pixels. The advantages of this snapshot device are elimination of the eye motion artifacts and pixel misregistration problems in traditional scanning-based hyperspectral retinal cameras, and real-time imaging of oxygen saturation dynamics with sub-second temporal resolution. The spectral imaging performance is demonstrated in a human retinal imaging experiment in vivo. The absorption spectral signatures of oxy-hemoglobin and macular pigments were successfully acquired by using this device.

Beneficial effect of antioxidants in retinopathies: a new hypothesis

The retina is the most oxygen consuming tissue of the body. Rod and cone photoreceptors efficiently carry out visual cascades, which are energetically costly processes. Data has recently been published that suggests that the metabolic support to phototransduction in the rod outer segment (OS) may originate directly in the OS, which is able to conduct aerobic metabolism. This oxygen-handling activity of the rod OS, which was never suspected before, appears to be a primary cause of the generation of reactive oxygen species directly inside the OS. Oxidative stress has been hypothesised to contribute to most of the neurodegenerative retinal pathologies, such as diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa and photoreceptor cell death after retinal detachment. Many natural antioxidant compounds are routinely used in experimental or human therapies for preventing or delaying photoreceptor degeneration in those pathologies. Here it is proposed that the ultimate reason for the beneficial actions of antioxidants in preventing or retarding the effect on the retinal degenerative pathologies can be found in their action on reactive oxygen species generated by the ectopic mitochondrial electron transport chain (ETC) coupled to FoF1-ATP synthase in rod OS disks. In fact, if not adequately coupled, the ETC generates reactive oxygen species that, in turn, can act on the polyunsaturated fatty acids which the rod OS is rich in. If correct, the mechanism put forward here would provide a potential for the molecular basis of therapies with antioxidants for retinal degenerative diseases.

Macular pigment changes in pseudophakic eyes quantified with resonance Raman spectroscopy

PURPOSE

We examined changes in macular pigment optical density (MPOD) levels after cataract surgery and compared the MPOD between eyes with clear intraocular lenses (IOLs) and yellow-tinted IOLs.

DESIGN

Prospective, comparative case series.

PARTICIPANTS

The MPOD levels were measured in 480 eyes of 337 patients after cataract surgery. Among them, the data from 259 eyes (clear IOL group, 121 eyes; yellow-tinted IOL group, 138 eyes) of 259 Japanese patients were selected for statistical analyses on the basis of the inclusion criteria: a postoperative visual acuity (VA) of ≥0.8 and no fundus diseases. Only 1 eye of each patient was enrolled. Patients provided informed consent to participate in this study on the basis of the approval of the institutional review board before surgery.

METHODS

The patients selected the type of IOL to be implanted. The MPOD levels were measured using resonance Raman spectroscopy on day 1 (baseline value); months 1, 3, and 6; and years 1 and 2 postoperatively.

MAIN OUTCOME MEASURES

The difference in MPOD levels between the IOL groups was analyzed by unpaired t tests. The following parameters were analyzed by multiple regression analysis: age, gender, body mass index (BMI), smoking history, glaucoma, diabetes, preoperative VA, preoperative refractive error, and IOL power and type.

RESULTS

We found no significant differences in the baseline characteristics between the 2 groups. Until 6 months postoperatively, the MPOD levels did not differ significantly between the groups. However, from 1 year onward, the levels were significantly higher in the yellow-tinted IOL group compared with the clear IOL group. By multiple regression analysis, 1 day postoperatively, older age and diabetes were correlated with lower MPOD levels; 1 year postoperatively and thereafter, however, lower MPOD levels were correlated with clear IOLs.

CONCLUSIONS

Cataract surgery with clear IOLs induced a greater decrease in macular pigment levels compared with yellow-tinted IOLs during a longer follow-up period. These findings agreed with observations that excessive light exposure is associated inversely with MPOD, because clear IOLs transmit higher intensities of blue light than yellow-tinted IOLs.

Role of long-chain and very-long-chain polyunsaturated fatty acids in macular degenerations and dystrophies

Macular degeneration is a progressive, bilateral eye disorder that damages the macula of the human eye. The most common form of macular degeneration is age-related macular degeneration (AMD), which is the leading cause of irreversible blindness in people older than 50 years in developed countries. Autosomal dominant Stargardt disease-3 (STGD3) is an inherited macular dystrophy that has clinical features similar to dry AMD, but occurs at a much earlier age. It is caused by a mutation in the elongation of very-long-chain fatty acids-like 4 (ELOVL4) gene, which is responsible for encoding the elongase enzyme that converts shorter chain fatty acids into C₂₈-C₃₈ very long-chain polyunsaturated fatty acids (VLCPUFAs, total number of carbons ≥24). Diets rich in long-chain polyunsaturated fatty acids (LCPUFAs) have inverse associations with the progression of AMD and STGD3, and a deficiency in retinal LCPUFAs and VLCPUFAs has been detected in AMD retinas and STGD3 animal models. This article systematically summarizes the roles of LCPUFAs and VLCPUFAs in AMD and STGD3, and discusses future research directions.

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.

Current Clinical Trials in Dry AMD and the Definition of Appropriate Clinical Outcome Measures

Currently, there is no proven drug treatment for dry age-related macular degeneration (AMD). Several different treatment strategies are being investigated, including complement inhibition, neuroprotection, and visual cycle inhibitors, and novel clinical trial endpoints are being explored. Studies have identified genetic predispositions for dry AMD associated with complement dysfunction. Consequently, complement-based therapeutic treatment modalities are promising.

Effect of 1-year lutein supplementation on macular pigment optical density and visual function

BACKGROUND

Although it is known that antioxidants including lutein can affect macular pigment optical density (MPOD) and visual function, we still have much to learn about their effect. Our aim was to assess the 1-year changes in MPOD and visual function in response to supplementation containing lutein.

METHODS

We prospectively measured the MPOD level of those who received a supplement containing 6 mg of lutein daily for 1 year. MPOD level was measured every 3 months by using autofluorescence spectrometry with the two-wavelength method. Other examinations, including contrast sensitivity and retinal sensitivity were also measured every 3 or 6 months. Stepwise regression analysis was performed to determine the factors that correlated with the changes observed in those examinations.

RESULTS

Forty-three eyes of 43 Japanese subjects, including five normal eyes, five fellow eyes with central serous chorioretinopathy (CSC), and 33 fellow eyes with age-related macular degeneration (AMD) were enrolled. The higher baseline MPOD level was correlated with the eye with a clear intraocular lens (IOL). Although no time-dependent changes in the MPOD level were obtained in any area, subjects without cardiovascular diseases showed higher increase in the MPOD level. We observed significant increases in the contrast sensitivity at 1 year (p = 0.0124) and in the retinal sensitivity at 6 months (p < 0.0001) and 1 year (p < 0.0001). Stepwise regression analysis showed that nonsmokers had increased contrast sensitivity (p = 0.0173), and the fellow eye of those with CSC had less of an increase in retinal sensitivity (p = 0.0491).

CONCLUSIONS

Daily supplementation with 6 mg of lutein did not affect the MPOD level for 1 year, suggesting that 6 mg of lutein may be insufficient to increase the MPOD level. However, supplementation seems to improve visual functions such as contrast sensitivity and retinal sensitivity.

Macular pigment distribution in Stargardt macular disease

PURPOSE

To investigate macular pigment optical density (MPOD) and distribution in patients with Stargardt disease.

METHODS

Prospective observational case series. The study included 13 eyes of 13 consecutive patients. A modified confocal scanning laser ophthalmoscope (SLO, Heidelberg, Germany) was used for MPOD measurement. It calculated the MPOD at 0.5° of the center of the fovea, and MPOD in the 0.5° and 2° areas.

RESULTS

Two different MPOD profile patterns were observed: group 1 was composed of patients with a flat profile, i.e., with very low MPOD in all locations, and group 2 presented a normal profile. In group 2, all eyes but one had good visual acuity (VA); in group 1, some displayed poor VA, but others had good VA. All patients in group 1 displayed a thinning of the macular area on OCT.

CONCLUSIONS

These results suggest that the flat MPOD profile, even if the visual acuity is good, could be associated with poor prognosis. The two different patterns of MPOD distribution described could reflect two different stages in the course of Stargardt disease. No strong correlations were found between MPOD profiles and visual acuity or macular thickness, but a straight trend was brought out that may indicate that the flat MPOD profile has a poor functional prognosis. Long follow-up is required to confirm this hypothesis.

Correlation of microperimetry with fundus autofluorescence and spectral-domain optical coherence tomography in repaired macular holes

PURPOSE

To investigate the correlation of microperimetry with fundus autofluorescence (FAF), spectral-domain optical coherence tomography (SD-OCT), and visual acuity (VA) in order to better characterize visual outcomes after successful macular hole (MH) surgery.

DESIGN

Cross-sectional case series.

METHODS

Postoperative VA, microperimetry, FAF, and SD-OCT images from 23 eyes of 23 patients who underwent successful MH surgery were obtained. FAF images were examined using the Heidelberg retina angiograph 2, and foveal structure and macular sensitivity were evaluated with SD-OCT and microperimetry. The mean retinal sensitivities within the central 9 degrees (microperimetry, mean), the retinal sensitivity of the foveal center (microperimetry, center), and the difference between the values obtained for the foveal center or mean of study and fellow eyes (microperimetry, centerdiff and microperimetry, meandiff, respectively) were measured with microperimetry.

RESULTS

Microperimetry (mean) was well correlated with microperimetry (center) in both study and fellow eyes. Poor postoperative VA was correlated with large microperimetry (meandiff). Following successful MH surgery, FAF of all eyes decreased markedly. There was a positive correlation between microperimetry (centerdiff) and degree of FAF of study eyes. However, a decrease in FAF after MH surgery was not correlated well with either degree of defect in the junction between photoreceptor inner and outer segment (IS/OS) or central retinal thickness on SD-OCT.

CONCLUSIONS

The amount of remaining FAF is related to macular sensitivity as measured by microperimetry after successful MH surgery. Function of photoreceptors and retinal pigment epithelium as well as integrity can be estimated by measuring the decrease in FAF after successful MH surgery. Moreover, functional correlation with microperimetry provides both morphologic and functional information on repaired MHs.

Human ocular carotenoid-binding proteins

Two dietary carotenoids, lutein and zeaxanthin, are specifically delivered to the human macula at the highest concentration anywhere in the body. Whenever a tissue exhibits highly selective uptake of a compound, it is likely that one or more specific binding proteins are involved in the process. Over the past decade, our laboratory has identified and characterized several carotenoid-binding proteins from human retina including a pi isoform of glutathione S-transferase (GSTP1) as a zeaxanthin-binding protein, a member of the steroidogenic acute regulatory domain (StARD) family as a lutein-binding protein, and tubulin as a less specific, but higher capacity site for carotenoid deposition. In this article, we review the purification and characterization of these carotenoid-binding proteins, and we relate these ocular carotenoid-binding proteins to the transport and uptake role of serum lipoproteins and scavenger receptor proteins in a proposed pathway for macular pigment carotenoid delivery to the human retina.

Studies on the singlet oxygen scavenging mechanism of human macular pigment

It is thought that direct quenching of singlet oxygen and scavenging free radicals by macular pigment carotenoids is a major mechanism for their beneficial effects against light-induced oxidative stress. Corresponding data from human tissue remains unavailable, however. In the studies reported here, electron paramagnetic resonance (EPR) spectroscopy was used to measure light-induced singlet oxygen generation in post-mortem human macula and retinal pigment epithelium/choroid (RPE/choroid). Under white-light illumination, production of singlet oxygen was detected in RPE/choroid but not in macular tissue, and we show that exogenously added macular carotenoids can quench RPE/choroid singlet oxygen. When the singlet oxygen quenching ability of the macular carotenoids was investigated in solution, it was shown that a mixture of meso-zeaxanthin, zeaxanthin, and lutein in a ratio of 1:1:1 can quench more singlet oxygen than the individual carotenoids at the same total concentration.

The retinal pigment epithelium: something more than a constituent of the blood-retinal barrier--implications for the pathogenesis of diabetic retinopathy

The retinal pigment epithelium (RPE) is an specialized epithelium lying in the interface between the neural retina and the choriocapillaris where it forms the outer blood-retinal barrier (BRB). The main functions of the RPE are the following: (1) transport of nutrients, ions, and water, (2) absorption of light and protection against photooxidation, (3) reisomerization of all-trans-retinal into 11-cis-retinal, which is crucial for the visual cycle, (4) phagocytosis of shed photoreceptor membranes, and (5) secretion of essential factors for the structural integrity of the retina. An overview of these functions will be given. Most of the research on the physiopathology of diabetic retinopathy has been focused on the impairment of the neuroretina and the breakdown of the inner BRB. By contrast, the effects of diabetes on the RPE and in particular on its secretory activity have received less attention. In this regard, new therapeutic strategies addressed to modulating RPE impairment are warranted.

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.

Risk factors for age-related maculopathy

Age-related maculopathy (ARM) is the leading cause of blindness in the elderly. Although beneficial therapeutic strategies have recently begun to emerge, much remains unclear regarding the etiopathogenesis of this disorder. Epidemiologic studies have enhanced our understanding of ARM, but the data, often conflicting, has led to difficulties with drawing firm conclusions with respect to risk for this condition. As a consequence, we saw a need to assimilate the published findings with respect to risk factors for ARM, through a review of the literature appraising results from published cross-sectional studies, prospective cohort studies, case series, and case control studies investigating risk for this condition. Our review shows that, to date, and across a spectrum of epidemiologic study designs, only age, cigarette smoking, and family history of ARM have been consistently demonstrated to represent risk for this condition. In addition, genetic studies have recently implicated many genes in the pathogenesis of age-related maculopathy, including Complement Factor H, PLEKHA 1, and LOC387715/HTRA1, demonstrating that environmental and genetic factors are important for the development of ARM suggesting that gene-environment interaction plays an important role in the pathogenesis of this condition.

Lutein and zeaxanthin in eye and skin health

Less than 20 of the hundreds of carotenoids found in nature are found in the human body. These carotenoids are present in the body from the foods or dietary supplements that humans consume. The body does not synthesize them. Among the carotenoids present in the body, only lutein and its coexistent isomer, zeaxanthin, are found in that portion of the eye where light is focused by the lens, namely, the macula lutea. Numerous studies have shown that lutein and zeaxanthin may provide significant protection against the potential damage caused by light striking this portion of the retina. In the eye, lutein and zeaxanthin have been shown to filter high-energy wavelengths of visible light and act as antioxidants to protect against the formation of reactive oxygen species and subsequent free radicals. Human studies have demonstrated that lutein and zeaxanthin are present in the skin, and animal studies have provided evidence of significant efficacy against light-induced skin damage, especially the ultraviolet wavelengths. Little was known about the protective effects of these carotenoids in human skin until recently. This article reviews the scientific literature pertaining to the effects that lutein and zeaxanthin exhibit in the human eye and skin.

Uncultivated Brazilian Green Leaves are Richer Sources of Carotenoids than are Commercially Produced Leafy Vegetables

Background

With the continuing problem of vitamin A deficiency, the recognition of the role of carotenoids in disease prevention, and international programs promoting biodiversity, determination of the carotenoid content of indigenous Brazilian foods is needed.

Objective

To determine the principal carotenoids in native leaves and compare the levels with those in commercially produced leafy vegetables.

Methods

The indigenous Brazilian leafy vegetables caruru, mentruz, taioba, serralha, and beldroega were analyzed with the use of a previously developed and validated high-performance liquid chromatography (HPLC) method. Parsley and coriander leaves, which were previously shown to be the richest in carotenoids among commercially produced leaves, were analyzed for comparison. Five sample lots of each vegetable collected at different times during the year were analyzed immediately after harvest.

Results

Lutein concentrations were 119 ± 21, 111 ± 48, 104 ± 44, 87 ± 7, and 34 ± 14 μg/g, and β-carotene contents were 114 ± 22, 97 ± 40, 66 ± 18, 72 ± 9, and 32 ± 14 μg/g for caruru, mentruz, taioba, serralha, and beldroega, respectively. Except for beldroega, these values were higher than those for commercial leaves. Parsley had 88 ± 18 μg/g of lutein and 65 ± 13 μg/g of β-carotene. Coriander leaves contained 74 ± 6 μg/g of lutein and 55 ± 5 μg/g of β-carotene. The violaxanthin and neoxanthin concentrations were also higher in the native leaves. Comparison with values for previously analyzed commercial leafy vegetables confirmed the higher carotenoid levels of the native leaves.

Conclusions

The indigenous leaves investigated are richer sources of carotenoids than are commercially produced leafy vegetables.

Possible degradation/biotransformation of lutein in vitro and in vivo: isolation and structural elucidation of lutein metabolites by HPLC and LC-MS (atmospheric pressure chemical ionization)

Metabolites of lutein are highly concentrated in the human macula and are known to provide protection against age-related macular degeneration. The aim of this investigation was to characterize the in vitro oxidation products of lutein obtained through photo-oxidation and to compare them with biologically transformed dietary lutein in intestine, plasma, liver, and eyes of rats. In vivo studies involved feeding rats a diet devoid of lutein for 2 weeks to induce deficiency. Rats were divided into two equal groups (n=6/group) and received either micellar lutein by gavage for 10 days or diet supplemented with fenugreek leaves as a lutein source for 4 weeks. Lutein metabolites/oxidation products obtained from in vivo and in vitro studies were characterized by HPLC and LC-MS (APCI) techniques to elucidate their structure. The characteristic fragmented ions resulting from photo-oxidation of lutein were identified as 523 (M(+)+H(+)-3CH(3)), 476 (M(+)+H(+)-6CH(3)), and 551 (M(+)+H(+)-H(2)O). In the eyes, the fragmented molecules resulting from lutein were 13-Z lutein, 13'-Z lutein, 13-Z zeaxanthin, all-E zeaxanthin, 9-Z lutein, 9'-Z lutein, and 3'-oxolutein. Epoxycarotenoids were identified in liver and plasma, whereas anhydrolutein was identified in intestine. This study emphasizes the essentiality of dietary lutein to maintain its status in the retina.

Measurement of macular pigment optical density and distribution using the steady-state visual evoked potential

The purpose of this study was to specify isoluminance at different retinal eccentricities and to characterize macular pigment optical density (MPOD) and distribution using the steady-state visual evoked potential (VEP). Redgreen (B/G) gratings were generated within two circular stimulus fields (radius = 0.55 or 1.1 deg) and within four annular fields (maximum mean radius = 6.0 deg) on a color monitor. Temporal frequency was 15 Hz. Isoluminance was determined for each stimulus using minimum flicker photometry. Steady-state onset-offset VEPs were recorded to the same annular stimuli as the luminance ratio between adjacent chromatic components was changed from 0.25 to 0.85 in 11 automated steps (0.5 representing photometric isoluminance). Fourier analysis showed that the power of the first harmonic was minimized at the isoluminant ratio specific to each subject. Relative OD was computed by comparing the isoluminant ratio at any location with that for the most eccentric annulus. To compensate for the broadband characteristics of the monitor, OD values were corrected according to minimum flicker measurements made through known concentrations of carotenoid solution. MPOD was additionally measured using minimum motion photometry.There was high correlation between the isoluminant ratios determined by minimum flicker and VEPs for both R/G and B/G stimulation (r = 0.91, P < 0.005, slope = 1). Calibrated OD values computed from VEP estimates of B/G isoluminance correlated with those derived from minimum flicker (r = 0.96, P < 0.0005, slope = 0.85) and motion photometry (r = 0.94, P < 0.0005, slope = 0.88). OD values derived from B/G VEPs increased toward the fovea and corresponded closely with minimum flicker and minimum motion assessment of MP distribution profiles. The steady-state VEP can be used to determine isoluminance at different retinal eccentricities. MPOD and distribution can be measured by steady-state VEPs to B/G stimuli.

Application of comprehensive two-dimensional liquid chromatography to elucidate the native carotenoid composition in red orange essential oil

In the present work, the ability of a LC x LC-DAD/APCI-MS method developed at this laboratory to identify the native composition of carotenoid in an extremely complex matrix such as red orange essential oil was demonstrated. To carry out this task, two independent and orthogonal separation mechanisms were coupled through a 10-port switching valve that simultaneously collected the eluent from a microbore cyano column used as the first dimension in normal phase mode and injected it to a conventional reversed phase monolithic C(18) column in the second dimension separation. By using this novel analytical technique together with the use of DAD and APCI-MS detectors it was possible to identify in the sample, without the need of any pretreatment, 40 different carotenoids. Among them, 16 carotenoid monoesters were identified, mainly beta-cryptoxanthin palmitate (C(16:0)), myristate (C(14:0)), and laureate (C(12:0)) as well as several lutein, violaxanthin, antheraxanthin, and luteoxanthin monoesters. Moreover, 21 carotenoid diesters composed by several antheraxanthin, luteoxanthin, violaxanthin, and auroxanthin diesters were found in the native carotenoid composition of the orange oil. The main carotenoid diesters were the laureate palmitate (C(12:0), C(16:0)), myristate palmitate (C(14:0), C(16:0)), and dipalmitate (C(16:0), C(16:0)) diesters, although other diesters were also identified. Besides, two different free carotenes, zeta-carotene and phytofluene, and a xanthophyll, lutein, were also determined. To the authors' knowledge, this is the first time that carotenoid diesters are described and identified in orange essential oil. Likewise, it has been demonstrated that the LC x LC approach proposed in this study is capable of coping with the direct analysis and identification of a complex natural source of carotenoids such as the orange.

Diet and risk factors for age-related maculopathy

BACKGROUND

Evidence continues to accumulate that oxidative stress is etiologically important in the pathogenesis of age-related maculopathy (ARM) and that appropriate antioxidants of dietary origin may protect against this condition.

OBJECTIVE

Risk factors for ARM may be classed as established or putative. We report a study designed to investigate whether such risk factors are associated with a dietary lack of antioxidants relevant to retinal health.

DESIGN

Dietary, anthropometric, and sociodemographic details relating to 828 healthy Irish subjects aged 20-60 y were recorded in a cross-sectional fashion and analyzed for associations between risk factors for ARM and dietary intake of relevant nutrients.

RESULTS

Of the established risk factors for ARM, increasing age was associated with a relative lack of dietary zeaxanthin (P < 0.05) and tobacco use with a relative lack of dietary vitamin C (P < 0.05). Of the putative risk factors for ARM, alcohol consumption was associated with a relative lack of dietary alpha-linoleic acid (P < 0.05), and female sex was associated with a relative lack of dietary zinc (P < 0.05).

CONCLUSIONS

We showed that several variables related to risk for ARM are associated with a relative dietary lack of key nutrients. Our finding that age, the most important and universal risk factor for ARM, is associated with a relative lack of dietary zeaxanthin, is an important finding that warrants further investigation.

Macular Pigment Lutein Is Antiinflammatory in Preventing Choroidal Neovascularization

Background— Choroidal neovascularization (CNV) is a critical pathogenesis in age-related macular degeneration, the most common cause of blindness in the developed countries. The aim of the current study was to investigate the effect of lutein supplementation on the development of the murine model of laser-induced CNV together with underlying molecular mechanisms.

Methods and Results— Mice were orally pretreated with lutein daily from 3 days before laser photocoagulation untill the end of the study. The index of CNV volume was significantly suppressed by the treatment with lutein, compared with vehicle-treated animals. Lutein treatment led to significant inhibition of macrophage infiltration into CNV and of the in vivo and in vitro expression of inflammation-related molecules including vascular endothelial growth factor, monocyte chemotactic protein −1, and intercellular adhesion molecule-1. Importantly, lutein suppressed IκB-α degradation and nuclear translocation of nuclear factor (NF)-κB p65 both in vivo and in vitro. Additionally, the development of CNV was significantly suppressed by inhibiting NF-κB p65 nuclear translocation, to the levels seen in the lutein treatment.

Conclusions— Lutein treatment led to significant suppression of CNV development together with inflammatory processes including NF-κB activation and subsequent upregulation of inflammatory molecules, providing molecular evidence of potential validity of lutein supplementation as a therapeutic strategy to suppress CNV.

Dietary Lutein/Zeaxanthin Partially Reduces Photoaging and Photocarcinogenesis in Chronically UVB-Irradiated Skh-1 Hairless Mice

Lutein and zeaxanthin are xanthophyll carotenoids with potent antioxidant properties protecting the skin from acute photodamage. This study extended the investigation to chronic photodamage and photocarcinogenesis. Mice received either a lutein/zeaxanthin-supplemented diet or a standard nonsupplemented diet. Dorsal skin of female Skh-1 hairless mice was exposed to UVB radiation with a cumulative dose of 16,000 mJ/cm(2) for photoaging and 30,200 mJ/cm(2) for photocarcinogenesis. Clinical evaluations were performed weekly, and the animals were sacrificed 24 h after the last UVB exposure. For photoaging experiments, skin fold thickness, suprapapillary plate thickness, mast cell counts and dermal desmosine content were evaluated. For photocarcinogenesis, samples of tumors larger than 2 mm were analyzed for histological characterization, hyperproliferation index, tumor multiplicity, total tumor volume and tumor-free survival time. Results of the photoaging experiment revealed that skin fold thickness and number of infiltrating mast cells following UVB irradiation were significantly less in lutein/zeaxanthin-treated mice when compared to irradiated animals fed the standard diet. The results of the photocarcinogenesis experiment were increased tumor-free survival time, reduced tumor multiplicity and total tumor volume in lutein/zeaxanthin-treated mice in comparison with control irradiated animals fed the standard diet. These data demonstrate that dietary lutein/zeaxanthin supplementation protects the skin against UVB-induced photoaging and photocarcinogenesis.

Regulation of the extracellular matrix remodeling by lutein in dermal fibroblasts, melanoma cells, and ultraviolet radiation exposed fibroblasts

With aging and cancer there is increased expression or activity of matrix metalloproteinases (MMPs) that degrade and remodel the structural extracellular matrix (ECM). In addition, exposure of skin to ultraviolet (UV) radiation (photoaging) leads to loss of cell viability, membrane damage, and deposition of excessive elastotic material. Lutein has antioxidant, anti-inflammatory, photoprotective, and anti-carcinogenic properties. The goal of this research was to investigate lutein's anti-aging and anti-carcinogenic effects via the regulation of the extracellular matrix remodeling. To this purpose, the effects of lutein on the expression of MMPs and their inhibitors (TIMPs, tissue inhibitors of metalloproteinases) in dermal fibroblasts (intrinsic aging) and melanoma cells were examined. Further, for lutein's photoprotective effects, the regulation of cell viability, membrane integrity, and elastin expression in the non-irradiated, and UVA or UVB radiation exposed fibroblasts were analyzed. Lutein significantly inhibited MMP-1 expression, transcriptionally, and MMP-2 protein levels in dermal fibroblasts, without altering TIMPs expression. It significantly inhibited MMP-1 expression in melanoma cells while stimulating TIMP-2. Lutein did not alter fibroblast or melanoma cell viability or membrane integrity. In ultraviolet radiation exposed fibroblasts, lutein improved cell viability, membrane integrity and inhibited elastin expression, though more significantly in the UVB exposed fibroblasts. In summary, the mechanism to lutein's anti-aging and anti-carcinogenic effects include the inhibition of MMP to TIMP ratio in dermal fibroblasts and melanoma cells, and the inhibition of cell loss, membrane damage and elastin expression in ultraviolet radiation exposed fibroblasts.

Macular pigment and lutein supplementation in ABCA4-associated retinal degenerations

PURPOSE

To determine macular pigment (MP) optical density (OD) in patients with ABCA4-associated retinal degenerations (ABCA4-RD) and the response of MP and vision to supplementation with lutein.

METHODS

Patients with Stargardt disease or cone-rod dystrophy and known or suspected disease-causing mutations in the ABCA4 gene were included. All patients had foveal fixation. MPOD profiles were measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity, and retinal thickness were quantified. Changes in MPOD and central vision were determined in a subset of patients receiving oral supplementation with lutein for 6 months.

RESULTS

MPOD in patients ranged from normal to markedly abnormal. As a group, patients with ABCA4-RD had reduced foveal MPOD, and there was a strong correlation with retinal thickness. Average foveal tissue concentration of MP, estimated by dividing MPOD by retinal thickness, was normal in patients, whereas serum concentration of lutein and zeaxanthin was significantly lower than normal. After oral lutein supplementation for 6 months, 91% of the patients showed significant increases in serum lutein, and 63% of the patients' eyes showed a significant augmentation in MPOD. The retinal responders tended to be female and to have lower serum lutein and zeaxanthin, lower MPOD, and greater retinal thickness at baseline. Responding eyes had significantly lower baseline MP concentration than did nonresponding eyes. Central vision was unchanged after the period of supplementation.

CONCLUSIONS

MP is strongly affected by the stage of ABCA4 disease leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in some patients. There was no change in central vision after 6 months of lutein supplementation. Long-term influences of this supplement on the natural history of these macular degenerations require further study.

Macular pigment optical density in the elderly: findings in a large biracial Midsouth population sample

PURPOSE

To report the macular pigment optical density (MPOD) findings at 0.5 degrees of eccentricity from the fovea in elderly subjects participating in ARMA, a study of aging and age-related maculopathy (ARM) ancillary to the Health, Aging, and Body Composition (Health ABC) Study.

METHODS

MPOD was estimated with a heterochromatic flicker photometry (HFP) method in a large biracial population sample of normal 79.1 +/- 3.2-year-old adults living in the Midsouth (n = 222; 52% female; 23% black, 34% users of lutein-containing supplements). Within a modified testing protocol, subjects identified the lowest and the highest target intensity at which the flicker sensation disappeared, and the exact middle of this "no-flicker zone" was interpolated by the examiner.

RESULTS

An MPOD estimate was obtained successfully in 82% of the participants. The mean MPOD in our sample was 0.34 +/- 0.21 (SD). The interocular correlation was high (Pearson's r = 0.82). Compared with lutein supplement users, mean MPOD was 21% lower in nonusers (P = 0.013). MPOD was also 41% lower in blacks than in whites (P = 0.0002), even after adjustment for lutein supplement use. There were no differences in MPOD by gender, iris color, or history of smoking.

CONCLUSIONS

Older adults in the Midsouth appear to have average MPOD and interocular correlation comparable to those in previous studies. Lutein supplement use and white race correlated with higher MPOD. No evidence of an age-related decline in MPOD was seen in the sample. The HFP method for the measurement of MPOD is feasible in epidemiologic investigations of the elderly, the group at highest risk of ARM.

Macular pigment in the human retina: histological evaluation of localization and distribution

PURPOSE

Clinical investigations have demonstrated variation in both the peak optical density and the spatial distribution of macular pigment. To confirm these impressions histologically, the present study examined the distribution of macular pigment in the human retina.

MATERIALS AND METHODS

The macular retina of 11 donor eyes of different ages (28-91 years) were examined histologically on 100 microm vibratome sections directly, without further staining. Measurements were made in two dimensions: (1) adding the number of macular sections with visible macular pigment, and (2) direct measurement of the extension of macular pigment in the foveolar section, which visibly contained the most macular pigment.

RESULTS

The measurements with two methods demonstrated good correlation. The macula demonstrated a variation in the spatial extension of the visible macular pigment between 200 and 900 microm diameter around the centre of the fovea, which was also found when direct measurements were taken. There was no correlation with the donor age. The main location of macular pigment was in the layer of the fibres of Henle in the fovea and in the inner nuclear layer at the parafoveal site.

CONCLUSIONS

Histologically, a wide variation of the spatial distribution of macular pigment was found that confirms clinical observations. The primary localization of human macular pigment is in the inner retinal layers.

Nutritional and clinical relevance of lutein in human health

Lutein is one of the most widely found carotenoids distributed in fruits and vegetables frequently consumed. Its presence in human tissues is entirely of dietary origin. Distribution of lutein among tissues is similar to other carotenoids but, along with zeaxanthin, they are found selectively at the centre of the retina, being usually referred to as macular pigments. Lutein has no provitamin A activity in man but it displays biological activities that have attracted great attention in relation to human health. Epidemiological studies have shown inconsistent associations between high intake or serum levels of lutein and lower risk for developing cardiovascular disease, several types of cancer, cataracts and age-related maculopathy. Also, lutein supplementation has provided both null and positive results on different biomarkers of oxidative stress although it is effective in increasing macular pigment concentration and in improving visual function in some, but not all, subjects with different eye pathologies. Overall, data suggest that whereas serum levels of lutein have, at present, no predictive, diagnostic or prognostic value in clinical practice, its determination may be very helpful in assessing compliance and efficacy of intervention as well as potential toxicity. In addition, available evidence suggests that a serum lutein concentration between 0·6 and 1·05 μmol/l seems to be a safe, dietary achievable and desirable target potentially associated with beneficial impact on visual function and, possibly, on the development of other chronic diseases. The use of lutein as a biomarker of exposure in clinical practice may provide some rationale for assessing its relationship with human health as well as its potential use within the context of evidence-based medicine.

Bioavailability of carotenoids and tocopherols from broccoli: in vivo and in vitro assessment

Fruits and vegetables are the major sources of biologically active compounds, and carotenoids and tocopherols constitute important groups in human diets. Bioavailability is a critical feature in the assessment of the role of micronutrients in human health, and the approaches to this issue include in vitro and in vivo methods. Our aim was to evaluate the bioavailability of carotenoids and tocopherols present in broccoli and to compare in vitro and in vivo approaches. Fourteen apparently healthy volunteers consumed 200 g broccoli once a day for seven days. Blood samples were drawn at baseline and after intervention to determine changes in lutein, beta-carotene, and alpha- and gamma-tocopherol as relevant phytochemicals provided with this vegetable. Broccoli also was subjected to simulated gastrointestinal digestion to assess changes related to preabsorptive processes. Analytes in serum and at each phase of the digestion were assayed by high-performance liquid chromatography. During the intervention, the amounts supplied daily ranged from 2.4 to 3.1 mg lutein, 1.4 to 1.8 mg beta-carotene, 4.5 to 6.8 mg alpha-tocopherol, and 0.8 to 1.8 mg gamma-tocopherol. Significant changes in serum in both men and women were observed only for lutein, whereas for gamma-tocopherol a significant change was detected in women. No changes were observed for alpha-tocopherol, beta-carotene, retinol, the alpha-tocopherol-to-cholesterol ratio, or serum lipids. Using the in vitro model, more than 75% of lutein, beta-carotene, gamma-tocopherol, and alpha-tocopherol remained at the duodenal phase, whereas incorporation into the supernatants accounted for <20% of the initial content in food. Regular consumption of broccoli at dietary levels increased serum concentrations of lutein and gamma-tocopherol without affecting alpha-tocopherol or beta-carotene status in serum. The behavior of these phytochemicals under in vitro gastrointestinal conditions does not fully explain the changes observed in vivo.

Risk factors for age-related maculopathy are associated with a relative lack of macular pigment

Macular pigment (MP) is composed of the two dietary carotenoids lutein (L) and zeaxanthin (Z), and is believed to protect against age-related maculopathy (ARM). This study was undertaken to investigate MP optical density with respect to risk factors for ARM, in 828 healthy subjects from an Irish population. MP optical density was measured psychophysically using heterochromatic flicker photometry, serum L and Z were quantified by HPLC, and dietary intake of L and Z was assessed using a validated food-frequency questionnaire. Clinical and personal details were also recorded, with particular attention directed towards risk factors for ARM. We report a statistically significant age-related decline in MP optical density (r2=0.082, p<0.01). Current and past smokers had lower average MP optical density than never smokers and this difference was statistically significant (p<0.01). Subjects with a confirmed family history of ARM had significantly lower levels of MP optical density than subjects with no known family history of disease (p<0.01). For each of these established risk factors, their statistically significant negative association with MP persisted after controlling for the other two, and also after controlling for other potentially confounding variables such as sex, cholesterol, dietary and serum L (p<0.01). In the absence of retinal pathology, and in advance of disease onset, the relative lack of MP seen in association with increasing age, tobacco use and family history of ARM supports the hypothesis that the enhanced risk that these variables represent for ARM may be attributable, at least in part, to a parallel deficiency of macular carotenoids.

Emerging drugs for age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness that until recently had no recognised drug treatment. In wet AMD, choroidal neovascularisation (CNV) causes a profound loss of central vision. CNV is a complex process in which tissue ischaemia and/or inflammation is thought to trigger production of angiogenic signal molecules. The release of VEGF appears to be particularly important. Verteporfin photodynamic therapy was the first drug therapy to be licensed for the treatment of some types of wet AMD. Other treatments directly targeting VEGF or other aspects of angiogenesis, such as pegaptanib, ranibizumab and anecortave acetate, have either recently been licensed or are in the advanced stages of development. These and other promising treatment options such as combination strategies are reviewed.

Guest editorial: Notes on the macular pigment

Potential functions of the macular pigment are reviewed. Its role as a protector of the retina in respect of the blue-light hazard, and its relation to the rods and the cones, are examined. It is tentatively suggested that its presence in the human retina originated in the wild as a result of diet and not as a special evolutionary process: the pigment does not appear to be able to offer any significant photic protection, and the effect on chromatic aberration, as recently reported, may be negligible. Its relation to the spectral placing of photopigments is also examined.