Correlation between Macular Pigment Optical Density and Neural Thickness and Volume of the Retina

In Vivo Correlation Between Macular Pigment Optical Volume and Retinal Layers Thickness

Purpose

This study aims to investigate the potential in vivo relationship between macular pigment (MP) and retinal layers thickness in healthy subjects and dry, non-advanced age-related macular degeneration (AMD).

Methods

An observational, cross-sectional study was conducted. Healthy subjects >40 years and patients with early or intermediate AMD were recruited. Structural OCT and macular pigment optical volume (MPOV) were collected for each subject. Retinal layers parameters were calculated based on the standard early treatment diabetic retinopathy study (ETDRS) map. Additionally, MPOV within 1°, 2°, and 9° of eccentricity was assessed and associated with retinal layers thickness and volume. Linear mixed-effects models were used to test the relationship between MP and structural OCT parameters, while adjusting for known possible confounding factors.

Results

A total of 144 eyes of 91 subjects (60.4% females) were evaluated, comprising 43% normal eyes and 57% with early/intermediate AMD. Among the retinal layers, only the outer nuclear layer (ONL) thickness and volume appeared to be associated to higher MP levels. Specifically, the central ONL thickness was identified as a significant predictor of the MPOV 1°(P = 0.04), while the parafoveal ONL thickness (inner ETDRS subfield) was identified as a significant fixed effect on the MPOV 9° (P = 0.037). Age and the presence of drusen or subretinal drusenoid deposits were also tested without showing significant correlations.

Conclusions

Among the retinal layers examined, only the ONL thickness demonstrated a significant association with MPOV. Consequently, ONL thickness might serve as a potential biomarker related to MP levels.

Lutein Loaded in β-Cyclodextrin Metal-Organic Frameworks for Stability and Solubility Enhancements

Lutein (Lut) is a recognized nutritional supplement known for its antioxidative and anti-inflammatory properties, crucial in mitigating ocular disease. However, enhancements to Lut stability and solubility remain challenges to be addressed in the healthcare industry. Herein, we fabricated and evaluated a food-grade highly porous β-cyclodextrin metal-organic framework (β-CD-MOF) for its ability to encapsulate Lut. Lut stability considerably improved when loaded into β-CD-MOF to form a Lut@β-CD-MOF complex, which exhibited better stability than Lut loaded into the γ-cyclodextrin metal-organic framework (Lut@γ-CD-MOF), Lut@β-CD, and commercial product (Blackmores™) at 40°C, 60°C, and 70°C, respectively. The solubility of Lut@β-CD-MOF in water increased by 26.8-fold compared to raw Lut at 37°C. Lut@β-CD-MOF exhibited greater hydrophilicity, as determined by measuring the water contact angle. Molecular docking and other characterizations of Fourier transform infrared spectroscopy and powder X-ray diffraction confirmed that Lut was successfully encapsulated in the chamber formed by the three cyclodextrins in β-CD-MOF. Thermogravimetric analysis and Raman spectroscopy demonstrated that Lut distributed in the β-CD-MOF cavity deeply improved Lut stability and solubility. In conclusion, our findings underscored the function of β-CD-MOF in enhancing Lut stability and solubility for formulation applications.

Low Macular Pigment Optical Density Is Associated with Manifest Primary Open-Angle Glaucoma in Older Women

Background

Lower density of carotenoids lutein and zeaxanthin (L/Z) in the macula (i.e., macular pigment) has been linked to greater risk for age-related eye disease.

Objectives

We evaluated whether macular pigment optical density (MPOD) was associated with manifest primary open-angle glaucoma (POAG) among older women in the Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2).

Methods

MPOD was measured with customized heterochromatic flicker photometry in women who attended CAREDS2 (2016-2019) and CAREDS1 (2001-2004) study visits. Manifest POAG at CAREDS2 was assessed using visual fields, disc photos, optical coherence tomography, and medical records. Age-adjusted linear and logistic regression models were used to investigate the cross-sectional association between POAG and MPOD at CAREDS2, and MPOD measured 15 years earlier at CAREDS1.

Results

Among 426 CAREDS2 participants (mean age: 80 y; range: 69-98 y), 26 eyes with manifest POAG from 26 participants were identified. Glaucomatous eyes had 25% lower MPOD compared to nonglaucomatous eyes [mean (SE): 0.40 (0.05) compared with 0.53 (0.01)] optical density units (ODU), respectively (P = 0.01). Compared with MPOD quartile 1, odds for POAG were lower for women in quartiles 2-4 (P-trend = 0.01). After excluding eyes with age-related macular degeneration, associations were similar but not statistically significant (P-trend = 0.16). Results were similar for MPOD measured at CAREDS1.

Conclusions

Our results add to growing evidence that low MPOD may be a novel glaucoma risk factor and support further studies to assess the utility of dietary interventions for glaucoma prevention.

Plant bioactive compounds alleviate photoinduced retinal damage and asthenopia: Mechanisms, synergies, and bioavailability

The retina, an important tissue of the eye, is essential in visual transmission and sustaining adequate eyesight. However, oxidative stress and inflammatory reactions can harm retinal structure and function. Recent studies have demonstrated that exposure to light can induce oxidative stress and inflammatory reactions in retinal cells, thereby facilitating the progression of retinal damage-related diseases and asthenopia. Plant bioactive compounds such as anthocyanin, curcumin, resveratrol, lutein, zeaxanthin, epigallocatechin gallate, and quercetin are effective in alleviating retinal damage and asthenopia. Their strong oxidation resistance and unique chemical structure can prevent the retina from producing reactive oxygen species and regulating eye muscle relaxation, thus alleviating retinal damage and asthenopia. Additionally, the combination of these active ingredients produces a stronger antioxidant effect. Consequently, understanding the mechanism of retinal damage caused by light and the regulation mechanism of bioactive compounds can better protect the retina and reduce asthenopia.

Association of macular pigment optical density with retinal layer thicknesses in eyes with and without manifest primary open-angle glaucoma

OBJECTIVE

To investigate associations between baseline macular pigment optical density (MPOD) and retinal layer thicknesses in eyes with and without manifest primary open-angle glaucoma (POAG) in the Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2).

METHODS AND ANALYSIS

MPOD was measured at CAREDS baseline (2001-2004) via heterochromatic flicker photometry (0.5° from foveal centre). Peripapillary retinal nerve fibre layer (RNFL), macular ganglion cell complex (GCC), ganglion cell layer (GCL), inner plexiform layer (IPL), and RNFL thicknesses were measured at CAREDS2 (2016-2019) via spectral-domain optical coherence tomography. Associations between MPOD and retinal thickness were assessed using multivariable linear regression.

RESULTS

Among 742 eyes (379 participants), manifest POAG was identified in 50 eyes (32 participants). In eyes without manifest POAG, MPOD was positively associated with macular GCC, GCL and IPL thicknesses in the central subfield (P-trend ≤0.01), but not the inner or outer subfields. Among eyes with manifest POAG, MPOD was positively associated with macular GCC, GCL, IPL and RNFL in the central subfield (P-trend ≤0.03), but not the inner or outer subfields, and was positively associated with peripapillary RNFL thickness in the superior and temporal quadrants (P-trend≤0.006).

CONCLUSION

We observed a positive association between MPOD and central subfield GCC thickness 15 years later. MPOD was positively associated with peripapillary RNFL superior and temporal quadrant thicknesses among eyes with manifest POAG. Our results linking low MPOD to retinal layers that are structural indicators of early glaucoma provide further evidence that carotenoids may be protective against manifest POAG.

Macular and Optic Disc Parameters in Children with Amblyopic and Nonamblyopic Eyes under Optical Coherence Tomography Fundus Images

The aim of this study was to investigate the characteristics of macular and optic disc parameters in children with amblyopic and nonamblyopic eyes, using fundus images under optical coherence tomography (OCT). 36 patients with anisometropic amblyopia were selected in the experimental group, and another 36 healthy volunteers were selected in the control group, OCT examinations were performed in all groups, and the mean diopter, mean corrected visual acuity (CVA), mean axial length, mean optic disc retinal nerve fiber layer (RNFL) thickness, and mean macular fovea thickness were recorded in the two groups. The results found that the average diopter of the patients in the control group and the experimental group was +2.30 ± 2.54 D and +5.51 ± 1.76 D, respectively. The average CVA was 0.86 ± 0.07 and 0.22 ± 0.16, respectively; the average eye axial length was 22.41 ± 1.20 mm and 21.11 ± 0.78 mm, respectively. As P < 0.05, the differences were statistically significant in the three indicators between the two groups. There was no significant difference between the two groups in the average thickness of the RNFL of the optic disc and the average thickness of the central fovea of macula (P > 0.05). There was some correlation among CVA, diopter, eye axial length, RNFL thickness, and average thickness of macular fovea, but the correlation was not significant. It was suggested that there were certain differences in the macular and optic disc parameters between amblyopic and nonamblyopic children, but the difference is little. Thereout, a certain objective basis was provided for the early detection and treatment of amblyopia.

Investigation of Serum and Macular Carotenoids in Central Serous Chorioretinopathy

Purpose

This study aimed to evaluate serum lutein and zeaxanthin levels and macular pigment optical density (MPOD) in central serous chorioretinopathy (CSC).

Methods

Fifty-four patients with acute CSC (28–56 years old; 44 men and 10 women) and 62 matched controls were enrolled. Serum lutein and zeaxanthin were measured using the high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method. MPOD was measured at 7° of eccentricity and reported in parameters as “max” and “mean” optical density (OD) (Visucam 200; Carl Zeiss Meditec). MPOD was re-measured in 9 patients whose subretinal fluid was absorbed.

Results

The average max OD and the mean OD in CSC were 0.275 ± 0.047 d.u. and 0.098 ± 0.018 d.u., respectively, which were significantly lower than the control (p &lt; 0.001). The average MPOD value in the unaffected eyes of patients with CSC was 0.298 ± 0.045 for max OD, 0.106 ± 0.017 for mean OD, and both were significantly lower compared with the affected eyes (p &lt; 0.001 for max OD, p = 0.01 for mean OD). In the 9 follow-up patients, the decrease in MPOD was partially recovered. The mean serum level was 409.80 ± 182.52 ng/ml for lutein and 22.97 ± 12.23 ng/ml for zeaxanthin in patients with CSC. In controls, the mean serum level was 393.38 ± 202.44 ng/ml for lutein and 22.16 ± 10.12 ng/ml for zeaxanthin. The difference was not statistically significant (p = 0.649, p = 0.698, respectively).

Conclusion

MPOD decreased within 7° of eccentricity in CSC without serum lutein and zeaxanthin changes. The decrease may be due to the subretinal fluid. Whether local oxidative stress is involved in CSC and the supplementation with lutein and zeaxanthin is helpful for CSC requires further investigation.

A Systematic Review of Carotenoids in the Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of modifiable vision loss in older adults. Chronic oxidative injury and compromised antioxidant defenses represent essential drivers in the development of retinal neurodegeneration. Overwhelming free radical species formation results in mitochondrial dysfunction, as well as cellular and metabolic imbalance, which becomes exacerbated with increasing age. Thus, the depletion of systemic antioxidant capacity further proliferates oxidative stress in AMD-affected eyes, resulting in loss of photoreceptors, neuroinflammation, and ultimately atrophy within the retinal tissue. The aim of this systematic review is to examine the neuroprotective potential of the xanthophyll carotenoids lutein, zeaxanthin, and meso-zeaxanthin on retinal neurodegeneration for the purpose of adjunctive nutraceutical strategy in the management of AMD. A comprehensive literature review was performed to retrieve 55 eligible publications, using four database searches from PubMed, Embase, Cochrane Library, and the Web of Science. Epidemiology studies indicated an enhanced risk reduction against late AMD with greater dietary consumption of carotenoids, meanwhile greater concentrations in macular pigment demonstrated significant improvements in visual function among AMD patients. Collectively, evidence strongly suggests that carotenoid vitamin therapies offer remarkable synergic protection in the neurosensory retina, with the potential to serve as adjunctive nutraceutical therapy in the management of established AMD, albeit these benefits may vary among different stages of disease.

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.

Oxidative stress in the light-exposed retina and its implication in age-related macular degeneration

The retina continuously receives light to enable vision, and the related processes require a marked amount of energy. During active metabolism, reactive oxygen species (ROS) are generated in exchange. Although physiologically generated ROS may be removed by endogenous antioxidant systems, and the effects of oxidative stress may be recovered by repair systems to retain homeostasis and health, when ROS and oxidative stress exceed the capacity of the antioxidant and repair systems, the condition becomes pathological. Multiple mechanisms of oxidative stress and the effects of antioxidant and repair systems in the retina have long been analyzed using light-induced retinal degeneration models. Among the mechanisms, a positive feedback loop of oxidative stress and related inflammation may be involved in the pathogenesis of a blinding aging disease, age-related macular degeneration. Treatments for suppressing ROS and oxidative stress by administrating antioxidant products may support the tissue-protective function of antioxidant systems. Moreover, recent studies have proposed a new concept for maintaining homeostasis by supplying sufficient energy to activate the repair systems. The current review will help elucidate the influence of oxidative stress and guide future analyses to explore new therapeutic approaches for oxidative stress-mediated diseases.

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Vision formation requires marked amounts of energy and produces ROS.

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Balanced oxidative stress and antioxidant/repair systems determine cellular health.

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ROS-modified molecules affect multiple pathways to cause cell death and disorders.

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A positive feedback loop of oxidative stress/related inflammation may lead to AMD.

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Homeostasis can be retained by supplying enough energy to activate repair systems.

Ocular and Systemic Effects of Antioxidative Supplement Use in Young and Healthy Adults: Real-World Cross-Sectional Data

Randomized controlled studies have shown that antioxidative supplements are effective in suppressing the progression of age-related macular degeneration and visual display terminal syndrome. However, effects of their general use in the real-world and by young and healthy individuals have not been well documented. We analyzed 27 participants who were under 35 years of age and had no diagnosed diseases. Mean functional visual acuity (FVA) score and visual maintenance ratio, which represent quick recognition of a target, both measured using FVA system, were better (both p < 0.01) in subjects who had had regular antioxidative supplement intake for more than 2 months (11 participants) compared with those who had not. Systemic data, i.e., total cholesterol, hemoglobin A1c (HbA1c), and high-sensitivity C-reactive protein (hs-CRP) levels, which correspond to chronic low-grade inflammation, were lower (all p < 0.05) in the former. Overall, hs-CRP levels had a correlation with total cholesterol (p < 0.05) and a trend of correlation with HbA1c (p = 0.054) levels. Thus, current real-world data showed that young, healthy participants who had a regular intake of antioxidative supplements had better visual acuity and systemic levels of metabolic and low-grade inflammation markers. This study will help promote future research into the effects of general antioxidative supplement use.