Lutein and Zeaxanthin Distribution in the Healthy Macula and Its Association with Various Demographic Factors Examined in Pseudophakic Eyes

Scavenging of Cation Radicals of the Visual Cycle Retinoids by Lutein, Zeaxanthin, Taurine, and Melanin

In the retina, retinoids involved in vision are under constant threat of oxidation, and their oxidation products exhibit deleterious properties. Using pulse radiolysis, this study determined that the bimolecular rate constants of scavenging cation radicals of retinoids by taurine are smaller than 2 × 107 M-1s-1 whereas lutein scavenges cation radicals of all three retinoids with the bimolecular rate constants approach the diffusion-controlled limits, while zeaxanthin is only 1.4-1.6-fold less effective. Despite that lutein exhibits greater scavenging rate constants of retinoid cation radicals than other antioxidants, the greater concentrations of ascorbate in the retina suggest that ascorbate may be the main protectant of all visual cycle retinoids from oxidative degradation, while α-tocopherol may play a substantial role in the protection of retinaldehyde but is relatively inefficient in the protection of retinol or retinyl palmitate. While the protection of retinoids by lutein and zeaxanthin appears inefficient in the retinal periphery, it can be quite substantial in the macula. Although the determined rate constants of scavenging the cation radicals of retinol and retinaldehyde by dopa-melanin are relatively small, the high concentration of melanin in the RPE melanosomes suggests they can be scavenged if they are in proximity to melanin-containing pigment granules.

Positive Association between Macular Pigment Optical Density and Glomerular Filtration Rate: A Cross-Sectional Study

Although decreased macular pigment density is associated with the development of age-related macular degeneration (AMD), exactly how this decrease may contribute to the development of AMD is still not fully understood. In this study, we investigated the relationship between macular pigment optical density (MPOD) and estimated glomerular filtration rate (eGFR). MPOD was measured using MPS II (Electron Technology, Cambridge, UK) in 137 participants who showed no clinical signs of AMD at 3 months after cataract surgery, and simple and multiple linear regression analyses were performed to determine the associations with age, sex, abdominal circumference, diabetes, hypertension, smoking, intraocular lens color, visual acuity before and after surgery, and eGFR. The participants were divided into two groups based on the median MPOD (0.58): the high-pigment and low-pigment groups. The mean value of eGFR in the high-pigment group was significantly higher than that in the low-pigment group (64.2 vs. 58.1, p = 0.02). The simple linear regression analysis revealed a significant positive association between MPOD and eGFR (β = 0.0034, 95% confidence interval [CI]: 0.0011-0.0056, p = 0.0038), and this association was independent of age, sex, abdominal circumference, diabetes, smoking, hypertension, best-corrected visual acuity (BCVA) before surgery, BCVA after surgery, and intraocular lens color (β = 0.0033, 95% CI: 0.00090-0.0058, p = 0.0076). These results show a strong association of renal dysfunction with the decrease in MPOD.

Nutritional Factors: Benefits in Glaucoma and Ophthalmologic Pathologies

Glaucoma is a chronic optic neuropathy that can lead to irreversible functional and morphological damage if left untreated. The gold standard therapeutic approaches in managing patients with glaucoma and limiting progression include local drops, laser, and/or surgery, which are all geared at reducing intraocular pressure (IOP). Nutrients, antioxidants, vitamins, organic compounds, and micronutrients have been gaining increasing interest in the past decade as integrative IOP-independent strategies to delay or halt glaucomatous retinal ganglion cell degeneration. In our minireview, we examine the various nutrients and compounds proposed in the current literature for the management of ophthalmology diseases, especially for glaucoma. With respect to each substance considered, this minireview reports the molecular and biological characteristics, neuroprotective activities, antioxidant properties, beneficial mechanisms, and clinical studies published in the past decade in the field of general medicine. This study highlights the potential benefits of these substances in glaucoma and other ophthalmologic pathologies. Nutritional supplementation can thus be useful as integrative IOP-independent strategies in the management of glaucoma and in other ophthalmologic pathologies. Large multicenter clinical trials based on functional and morphologic data collected over long follow-up periods in patients with IOP-independent treatments can pave the way for alternative and/or coadjutant therapeutic options in the management of glaucoma and other ocular pathologies.

Systematic Review of Reflection Spectroscopy-Based Skin Carotenoid Assessment in Children

Assessing children's skin carotenoid score (SCS) using reflection spectroscopy (RS) is a non-invasive, widely used method to approximate fruit and vegetable consumption (FVC). The aims for the current review were to (1) identify distributions of SCS across demographic groups, (2) identify potential non-dietary correlates for RS-based SCS, (3) summarize the validity and reliability of RS-based SCS assessment, and (4) conduct meta-analyses of studies examining the correlation between RS-based SCS with FVC. A literature search in eight databases in June 2021 resulted in 4880 citations and peer-reviewed publications written in English that investigated children's (2-10 years old) SCS using RS. We included 11 studies (intervention = 3, observational = 8). Potential covariates included weight status, ethnicity, seasonal variation, age, sex, and income. Studies reported criterion validity with children's FVC but not with plasma carotenoid. Additionally, no studies reported the reliability of RS-based SCS in children. Among the 726 children included in the meta-analysis, the correlation between RS-based SCS and FVC was r = 0.2 (p < 0.0001). RS-based SCS is a valid method to quantify skin carotenoids for children's FVC estimation with the potential for evaluating nutrition policies and interventions. However, future research should use standardized protocol for using RS and establish how RS-based SCS can translate to the amount of daily FVC in children.

Fingertip-Measured Skin Carotenoids and Advanced Glycation End Product Levels in Glaucoma

Carotenoids have antioxidant properties, and the accumulation of advanced glycation end products (AGEs) is associated with reactive oxygen species production; they have attracted attention as factors predictive of the onset and progression in glaucoma. Fingertip measurement is applicable for carotenoids and AGEs due to its noninvasiveness and simplicity. The study included 663 eyes of 663 Japanese subjects (357 males, 306 females). The mean age was 69.9 years with a standard deviation of 11.0. The study population comprised participants with primary open-angle glaucoma (PG) (n = 358), exfoliation glaucoma (EG) (n = 168), and controls (n = 137). Multivariate models suggested that lower skin carotenoid (SC) levels were associated with male gender (standard β = −0.14), AGE scores (−0.24), and a history of intraocular surgery (−0.22). Higher SC levels were associated with higher vegetable intake scores (0.21 for score 3) and diabetes (0.10). However, no association was seen between SCs and glaucoma type. AGEs levels were negatively associated with carotenoid scores (−0.25), PG (−0.15), and smoking habits (−0.26) and positively correlated with EG (0.14). SCs and AGEs were negatively correlated in the single regression analysis (r = −0.20, p < 0.0001). In conclusion, higher levels of AGEs may be candidates for systemic biomarkers of glaucoma associated with the exfoliation syndrome. SC levels can reflect self-reported daily vegetable intake.