Blue Light Exposure: Ocular Hazards and Prevention-A Narrative Review.

INTRODUCTION: Exposure to blue light has seriously increased in our environment since the arrival of light emitting diodes (LEDs) and, in recent years, the proliferation of digital devices rich in blue light. This raises some questions about its potential deleterious effects on eye health. The aim of this narrative review is to provide an update on the ocular effects of blue light and to discuss the efficiency of methods of protection and prevention against potential blue light-induced ocular injury. METHODS: The search of relevant English articles was conducted in PubMed, Medline, and Google Scholar databases until December 2022. RESULTS: Blue light exposure provokes photochemical reactions in most eye tissues, in particular the cornea, the lens, and the retina. In vitro and in vivo studies have shown that certain exposures to blue light (depending on the wavelength or intensity) can cause temporary or permanent damage to some structures of the eye, especially the retina. However, currently, there is no evidence that screen use and LEDs in normal use are deleterious to the human retina. Regarding protection, there is currently no evidence of a beneficial effect of blue blocking lenses for the prevention of eye diseases, in particular age-related macular degeneration (AMD). In humans, macular pigments (composed of lutein and zeaxanthin) represent a natural protection by filtering blue light, and can be increased through increased intake from foods or food supplements. These nutrients are associated with lower risk for AMD and cataract. Antioxidants such as vitamins C, E, or zinc might also contribute to the prevention of photochemical ocular damage by preventing oxidative stress. CONCLUSION: Currently, there is no evidence that LEDs in normal use at domestic intensity levels or in screen devices are retinotoxic to the human eye. However, the potential toxicity of long-term cumulative exposure and the dose-response effect are currently unknown.

A Randomized Study of Nutritional Supplementation in Patients with Unilateral Wet Age-Related Macular Degeneration.

The purpose of this study is evaluate the efficacy and safety of medicinal products containing the original Age-Related Eye Disease group (AREDS) formulation at doses approved in Europe (EU, control group; n = 59) with a product that adds DHA, lutein, zeaxanthin, resveratrol and hydroxytyrosol to the formula (intervention group; n = 50). This was a multicenter, randomized, observer-blinded trial conducted in patients aged 50 years or older diagnosed with unilateral exudative Age related Macular Degeneration AMD. At month 12, the intervention did not have a significant differential effect on visual acuity compared with the control group, with an estimated treatment difference in Early Treatment Diabetic Retinopathy Study (ETDRS) of -1.63 (95% CI -0.83 to 4.09; p = 0.192). The intervention exhibited a significant and, in most cases, relevant effect in terms of a reduction in some inflammatory cytokines and a greater improvement in the fatty acid profile and serum lutein and zeaxantin concentration. In patients with unilateral wet AMD, the addition of lutein, zeaxanthin, resveratrol, hydroxytyrosol and DHA to the AREDS EU recommended doses in the short-term did not have a differential effect on visual acuity compared to a standard AREDS EU formula but, in addition to improving the fatty acid profile and increasing carotenoid serum levels, may provide a beneficial effect in improving the proinflammatory and proangiogenic profile of patients with AMD.

Higher Intake of Polyunsaturated Fatty Acid and Monounsaturated Fatty Acid is Inversely Associated With AMD.

Purpose: To evaluate the association between dietary fat intake and the presence of AMD. Methods: Cross-sectional, observational study with cohorts prospectively recruited from the United States and Portugal. AMD was diagnosed based on color fundus photographs with the AREDS classification. A validated food frequency questionnaire was used to calculate the percent energy intake of trans fat, saturated fat, monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA). Odds ratio (OR) and 95% confidence intervals for quintile of amount of FA were calculated. Multiple logistic regression was used to estimate the OR. Results: We included 483 participants, 386 patients with AMD and 97 controls. Higher intake of trans fat was associated with a 2.3-fold higher odds of presence of AMD (P for trend = 0.0156), whereas a higher intake of PUFA (OR, 0.25; P for trend = 0.006) and MUFA (OR, 0.24; P for trend < 0.0001) presented an inverse association. Subgroup analysis showed that higher quintile of trans fat was associated with increased odds of having intermediate AMD (OR, 2.26; P for trend = 0.02); and higher quintile of PUFA and MUFA were inversely associated with intermediate AMD (OR, 0.2 [P for trend = 0.0013]; OR, 0.17 [P for trend < 0.0001]) and advanced AMD (OR, 0.13 [P for trend = 0.02]; OR, 0.26 [P for trend = 0.004]). Additionally, a statistically significant effect modification by country was noted with inverse association between MUFA and AMD being significant (OR, 0.04; P for trend < 0.0001) for the Portugal population only. Conclusions: Our study shows that higher dietary intake of trans fat is associated with the presence of AMD, and a higher intake of PUFA and MUFA is inversely associated with AMD.

Gastroprotective and antielastase effects of protein inhibitors from Erythrina velutina seeds in an experimental ulcer model.

Trypsin and chymotrypsin inhibitors from Erythrina velutina seeds have been previously isolated by our group. In previous studies using a sepsis model, we demonstrated the antitumor and anti-inflammatory action of these compounds. This study aimed to evaluate the gastroprotective and antielastase effects of protein inhibitors from E. velutina seeds in an experimental stress-induced ulcer model. Two protein isolates from E. velutina seeds, with antitrypsin (PIAT) and antichymotrypsin (PIAQ) activities, were tested. Both protein isolates showed a high affinity and inhibitory effect against human neutrophil elastase, with 84% and 85% inhibition, respectively. Gastric ulcer was induced using ethanol (99%) in 6 groups of animals (female Wistar rats, n = 6). Before ulcer induction, these animals were treated for 5 days with one of the following: (1) PIAT (0.2 mg·kg-1), (2) PIAT (0.4 mg·kg-1), (3) PIAQ (0.035 mg·kg-1), (4) ranitidine hydrochloride (50 mg·kg-1), (5) saline solution (0.9%), or (6) no intervention (sham). Both PIAT and PIAQ protected gastric mucosa, preventing hemorrhagic lesions, edema, and mucus loss. No histologic toxic effects of PIAT or PIAQ were seen in liver and pancreatic cells. Our results show that protein isolates from E. velutina seeds have potential gastroprotective effects, placing these compounds as natural candidates for gastric ulcer prevention.

Omega-3 Fatty Acids and Age-Related Macular Degeneration.

Against a background of considerable epidemiological and other evidence implicating omega-3 fatty acids in the prevention of age-related macular degeneration (AMD), the negative results of the Age-Related Disease Study 2 (AREDS2) were unexpected. The possibility that the design, setting, intake or subjects of AREDS2 may not have permitted the prophylactic potential of omega-3 to be adequately demonstrated is considered. Epidemiological studies had indicated potential preventative effects of omega-3, and an earlier randomised prospective study (NAT2) showed that patients who achieved high red blood cell membrane EPA/DHA (eicosapentaenoic acid/docosahexaenoic acid) levels were significantly protected against AMD compared with those with permanently low EPA/DHA levels. Various methodological differences between these studies are considered. NAT2 included a true placebo group, whereas control subjects in AREDS2 received a nutritional formula already found to be effective in AREDS1, but no placebo for DHA/EPA supplementation. Differences in the handling of non-compliant subjects and the formulation of the test formulations are considered. Given these considerations, and other lines of evidence from laboratory and clinical studies, closing the chapter on omega-3 in AMD prevention may be premature.

European survey on the opinion and use of micronutrition in age-related macular degeneration: 10 years on from the Age-Related Eye Disease Study.

PURPOSE: To evaluate ophthalmologists' opinion of, and use of, micronutritional dietary supplements 10 years after publication of the first Age-Related Eye Disease Study (AREDS) study. METHODS: Participation was solicited from 4,000 European ophthalmologists. Responding physicians were screened, and those treating at least 40 patients with age-related macular degeneration (AMD) per month and prescribing nutrition supplements at least 4 times per month were admitted and completed a 40-item questionnaire. RESULTS: The surveyed sample included 112 general ophthalmologists and 104 retinal specialists. Most nutritional supplements (46%) were initiated when early/intermediate AMD was confirmed, although 18% were initiated on confirmation of neovascular AMD. Clinical studies were well known: 90% were aware of AREDS, with 88% aware of AREDS1 and 36% aware of the, as-yet-unpublished, AREDS2 studies. Respondents considered lutein, zeaxanthin, zinc, omega-3, and vitamins to be the most important components of nutritional supplements, with the results of AREDS2 already having been taken into consideration by many. Ophthalmologists anticipate more scientific studies as well as improved product quality but identify cost as a barrier to wider uptake. CONCLUSION: Micronutrition is now part of the routine management of AMD for many ophthalmologists. Ophthalmologists choosing to use nutritional supplements are well-informed regarding current scientific studies.

Micronutrients in age-related macular degeneration.

Several lines of evidence from in vitro and in vivo studies suggest that specific micronutrients may have beneficial effects in age-related macular degeneration (AMD). Such effects appear to be complex and may include filtering short wavelength light and attenuating oxidative and inflammatory damage as well as other structural and physiological factors. There is clinical evidence for potential benefits from vitamin C, ß-carotene, vitamin E and zinc, as well as emerging epidemiological and clinical data for the carotenoids lutein and zeaxanthin and for omega-3 fatty acids. A survey of the literature suggests that some specific micronutrients may be of value in treating or preventing AMD, but further prospective studies are needed to further identify and characterize their effects and place in therapy.