Primary open-angle glaucoma patients have reduced levels of blood docosahexaenoic and eicosapentaenoic acids

Associations of circulating vitamins with 10-year retinal neurodegeneration: the Alienor Study

OBJECTIVE

To investigate the associations between circulating vitamins A, D, E, B6, B9, B12 and longitudinal changes in retinal nerve fiber layer (RNFL) thickness.

METHODS

The Alienor study, a prospective population-based cohort (Bordeaux, France), includes 963 individuals aged 73 years or older at baseline. The present study included 646 participants with complete RNFL measurement and vitamins. Study period is from 2009 to 2020. Peripapillary RNFL thickness was measured using spectral domain optical coherence tomography (SD-OCT). Plasma vitamins A, D and E and, serum vitamins B6, B9 and B12 were measured from blood sample. We performed linear mixed models, adjusted for age, gender, axial length, family history of glaucoma, and alcohol consumption to evaluated associations between vitamins and RNFL thickness changes over time.

RESULTS

Individuals having higher concentrations of vitamin E, D and B9 had a slower RNFL thinning during the 10-years of follow-up. Indeed, a 1-standard deviation (SD) increase of vitamin E (10.8 μmol/L), D (17.6 nmol/L) and B9 (11 μmol/L) were associated with slower RNFL thinning by 0.14 μm/year (95% confidence interval (CI), 0.03-0.25, p = 0.01), 0.14 μm/year (95% CI, 0.02-0.27, p = 0.02) and 0.11 μm/year (95% CI: 0.007-0.21, p = 0.04), respectively. No significant associations were observed for vitamins A, B6 and B12 with RNFL thinning.

CONCLUSIONS

Higher levels of vitamins E, D and B9 were associated with a slower RNFL thickness on SD-OCT over time, suggesting that those vitamins may contribute to the neuroprotection of the retina.

The potential impact of a vegetarian diet on glaucoma

Treatment of primary open-angle glaucoma has centered on the lowering of intraocular pressure that damages the optic nerve; however, this strategy is not uniformly successful, especially in normal tension glaucoma, and there is interest in antioxidant, anti-inflammatory, and other neuroprotective strategies. Vegetarian diets are known to be rich in antioxidant and anti-inflammatory components and have a number of established health benefits. Thus, it would be reasonable to assume that vegetarian diets would be beneficial in glaucoma, but this approach has not been well studied. We examine the possible role of vegetarian diets and their components in the incidence and progression of glaucoma.

Association of Gene Polymorphisms with Normal Tension Glaucoma: A Systematic Review and Meta-Analysis

BACKGROUND

Normal tension glaucoma (NTG) is becoming a more and more serious problem, especially in Asia. But the pathological mechanisms are still not illustrated clearly. We carried out this research to uncover the gene polymorphisms with NTG.

METHODS

We searched in Web of Science, Embase, Pubmed and Cochrane databases for qualified case-control studies investigating the association between single nucleotide polymorphisms (SNPs) and NTG risk. Odds ratios (ORs) and 95% confidence intervals (CIs) for each SNP were estimated by fixed- or random-effect models. Sensitivity analysis was also performed to strengthen the reliability of the results.

RESULTS

Fifty-six studies involving 33 candidate SNPs in 14 genetic loci were verified to be eligible for our meta-analysis. Significant associations were found between 16 SNPs (rs166850 of OPA1; rs10451941 of OPA1; rs735860 of ELOVL5; rs678350 of HK2; c.603T>A/Met98Lys of OPTN; c.412G>A/Thr34Thr of OPTN; rs10759930 of TLR4; rs1927914 of TLR4; rs1927911 of TLR4; c.*70C>G of EDNRA; rs1042522/-Arg72Pro of P53; rs10483727 of SIX1-SIX6; rs33912345 of SIX1-SIX6; rs2033008 of NCK2; rs3213787 of SRBD1 and c.231G>A of EDNRA) with increased or decreased risk of NTG.

CONCLUSIONS

In this study, we confirmed 16 genetic polymorphisms in 10 genes (OPA1, ELOVL5, HK2, OPTN, TLR4, EDNRA, P53, NCK2, SRBD1 and SIX1-SIX6) were associated with NTG.

Towards modifying the genetic predisposition for glaucoma: An overview of the contribution and interaction of genetic and environmental factors

Glaucoma, the leading cause of irreversible blindness worldwide, is a complex human disease, with both genetic and environmental determinants. The availability of large-scale, population-based cohorts and biobanks, combining genotyping and detailed phenotyping, has greatly accelerated research into the aetiology of glaucoma in recent years. Hypothesis-free genome-wide association studies have furthered our understanding of the complex genetic architecture underpinning the disease, while epidemiological studies have provided advances in the identification and characterisation of environmental risk factors. It is increasingly recognised that the combined effects of genetic and environmental factors may confer a disease risk that reflects a departure from the simple additive effect of the two. These gene-environment interactions have been implicated in a host of complex human diseases, including glaucoma, and have several important diagnostic and therapeutic implications for future clinical practice. Importantly, the ability to modify the risk associated with a particular genetic makeup promises to lead to personalised recommendations for glaucoma prevention, as well as novel treatment approaches in years to come. Here we provide an overview of genetic and environmental risk factors for glaucoma, as well as reviewing the evidence and discussing the implications of gene-environment interactions for the disease.

Is fat the future for saving sight? Bioactive lipids and their impact on glaucoma

Glaucoma is characterized by a continuous loss of retinal ganglion cells. The cause of glaucoma is associated with an increase in intraocular pressure (IOP), but the underlying pathophysiology is diverse and, in most cases, unknown. There is an indisputable unmet need to identify new pathways involved in glaucoma pathogenesis. Increasing evidence suggests that bioactive lipids may be critical in the development and progression of glaucoma. Preclinical and clinical bioactive lipid targets exist and are being developed. In this review, we aim to shed light on the potential of bioactive lipids for the prevention, diagnosis, prognosis, and treatment of glaucoma by asking the question "is fat the future for saving sight".

Deuterated polyunsaturated fatty acids provided protection against oxidative stress in ocular fibroblasts derived from glaucoma patients

Glaucoma is a complex neurodegenerative disease of the optic nerve that leads to irreversible sight loss. Lowering intraocular pressure (IOP) medically or surgically represents the mainstay of treatment but despite adequate treatment optic nerve function can continue to deteriorate leading to blindness. There is significant clinical and experimental evidence that oxidative stress is involved in the pathogenesis of glaucoma. Decreasing the formation of lipid peroxidation products or scavenging them chemically could be beneficial in limiting the deleterious effects of oxidative stress in glaucoma. A solution to control the susceptibility of PUFAs to noxious lipid peroxidation reactions is by regioselective deuteration. Deuterium incorporated into PUFAs at bis-allylic positions (D-PUFAs) inhibits the rate-limiting step of lipid peroxidation. In this study, we have shown that Tenon's ocular fibroblasts from glaucoma patients have significantly increased basal oxidative stress compared to non-glaucomatous control patients. Furthermore, we have shown that deuterated polyunsaturated fatty acids (D-PUFAs) provide an enhanced rescue of menadione induced lipid peroxidation in both non-glaucomatous and glaucomatous Tenon's ocular fibroblasts using malondialdehyde (MDA) levels as a marker. Our study suggests that D-PUFAs may provide a potentially safe and effective method to reduce cytotoxic oxidative stress in glaucoma.

The Effect of Oral Citicoline and Docosahexaenoic Acid on the Visual Field of Patients with Glaucoma: A Randomized Trial

The role of nutraceuticals in the treatment of glaucoma remains controversial. The aim of this study was to evaluate the effect of citicoline, vitamin C, and docosahexaenoic acid (DHA) in patients with glaucoma. Methods: This was a prospective, randomized study. Patients with glaucoma were randomized to one of four groups and treated for 3 months with vitamin C, DHA, citicoline, or a combination of DHA and citicoline. We conducted a complete ophthalmic examination and visual fields each month and calculated the slopes of field indices. Changes in visual field indices (VFIs) and their slopes were assessed in each group and compared. Results: Seventy-three persons were included in the study. Mean defect (MD) significantly improved (p = 0.001) from −9.52 ± 4.36 to −7.85 ± 4.36 dB during the study period in persons taking DHA + citicoline. Similarly, the mean VFI significantly improved (p = 0.001) in this group. The only treatment group showing a statistically significant improvement (p = 0.006) in the MD (from −0.1041 ± 0.2471 to 0.1383 ± 0.2544 dB/month) and VFI slope was the group treated with DHA+citicoline. Conclusions: The combination of oral treatment with DHA + citicoline significantly improved VF indices and their slopes in patients with glaucoma after 3 months of treatment.

Circulating fatty acids and risk of primary open-angle glaucoma: A mendelian randomization study

PURPOSE

The relationship between fatty acids (FAs) and glaucoma remains controversial despite several observational studies. We organized a mendelian randomization (MR) study to determine the genetic causal association between circulating FAs and primary open-angle glaucoma (POAG).

METHODS

The two-sample MR method was used to acquire causal estimates. Fourteen distinct single nucleotide polymorphisms (SNPs) of ten FAs were chosen as instrumental variables (IVs) at a genome-wide significance level (p < 5 × 10^-8). Summary statistics for POAG were available from a genome-wide association meta-analysis of 216,257 individuals of European ancestry (16,677 cases, 199,580 controls). The inverse-variance weighted (IVW) method was adopted to evaluate the causality of FAs and POAG. Multiple sensitivity analyses were applied to avoid pleiotropy.

RESULTS

The IVW method suggested no evidence to support causal effects of ten FAs on POAG. The odds ratio (OR) per one SD increment of each FA was OR_ALA = 1.64 (95% CI, 0.441-6.098, p = 0.46), OR_EPA = 0.815 (95% CI, 0.604-1.101, p = 0.182), OR_DPA = 0.896 (95% CI, 0.669-1.198, p = 0.458), OR_DHA = 1.014 (95% CI, 0.801-1.283, p = 0.91), OR_LA = 1.008 (95% CI, 0.971-1.045, p = 0.683), OR_AA = 0.993 (95% CI, 0.973-1.013, p = 0.483), OR_POA = 0.731 (95% CI, 0.261-2.048, p = 0.551), OR_OA = 1.048 (95% CI, 0.934-1.175, p = 0.425), OR_PA = 1.039 (95% CI, 0.903-1.196, p = 0.593), OR_SA = 0.967 (95% CI, 0.879-1.062, p = 0.477). Moreover, Sensitivity analysis indicated no pleiotropy.

CONCLUSION

This MR study does not support causal associations between ten FAs and POAG.

Reported evidence of vitamin E protection against cataract and glaucoma

Cataract and glaucoma are the major causes of severe visual loss and blindness in older adults. This review article describes the currently available basic and clinical evidence regarding vitamin E protection against these eye diseases in the chronologic order of the publications. Experimental evidence has suggested both that oxidative stress due to the accumulation of free radicals plays a role in the pathogenesis of cataracts and glaucoma and that the process can be prevented or ameliorated by vitamin E. The results of observational studies have been inconsistent regarding the association between blood vitamin E levels and the risk of age-related cataract or glaucoma. Despite the encouraging effects of vitamin E from case series, case-control studies, and cross-sectional studies in humans, the effects on cataract formation and/or progression have not been consistent among prospective and randomized control studies; few randomized control studies have tested the effects of supplemental vitamin E on glaucoma development or progression. Given the high prevalence of cataract and glaucoma in the elderly population, even a modest reduction in the risk for these eye diseases would potentially have a substantial public health impact; however, the potential benefits of vitamin E on cataract or glaucoma remain inconclusive and need to be carefully considered.

Non-drug interventions in glaucoma: Putative roles for lifestyle, diet and nutritional supplements

Glaucoma is a major ocular neurodegenerative disease characterized by progressive retinal ganglion cells degeneration and sight loss. Current treatment options have been limited to reducing intraocular pressure (IOP), known as the leading risk factor for this disease; however, glaucoma can develop even with low or normal IOP and progress despite controlling IOP values. Lifestyle, dietary habits, and supplementation may influence some of the risk factors and pathophysiological mechanisms underlying glaucoma development and progression; thus, the role of this complementary and alternative medicine in glaucoma has received great interest from both patients and ophthalmologists. We provide a summary of the current evidence concerning the relationship between lifestyle, dietary habits, and effects of supplements on the incidence and progression of glaucoma and their targets and associated mechanisms. The data suggest the existence of a therapeutic potential that needs to be further explored with both preclinical and rigorous clinical studies.

Candidate Glaucoma Biomarkers: From Proteins to Metabolites, and the Pitfalls to Clinical Applications

Glaucoma is an insidious group of eye diseases causing degeneration of the optic nerve, progressive loss of vision, and irreversible blindness. The number of people affected by glaucoma is estimated at 80 million in 2021, with 3.5% prevalence in people aged 40-80. The main biomarker and risk factor for the onset and progression of glaucoma is the elevation of intraocular pressure. However, when glaucoma is diagnosed, the level of retinal ganglion cell death usually amounts to 30-40%; hence, the urgent need for its early diagnosis. Molecular biomarkers of glaucoma, from proteins to metabolites, may be helpful as indicators of pathogenic processes observed during the disease's onset. The discovery of human glaucoma biomarkers is hampered by major limitations, including whether medications are influencing the expression of molecules in bodily fluids, or whether tests to validate glaucoma biomarker candidates should include human subjects with different types and stages of the disease, as well as patients with other ocular and neurodegenerative diseases. Moreover, the proper selection of the biofluid or tissue, as well as the analytical platform, should be mandatory. In this review, we have summarized current knowledge concerning proteomics- and metabolomics-based glaucoma biomarkers, with specificity to human eye tissue and fluid, as well the analytical approach and the main results obtained. The complex data published to date, which include at least 458 different molecules altered in human glaucoma, merit a new, integrative approach allowing for future diagnostic tests based on the absolute quantification of local and/or systemic biomarkers of glaucoma.

Alterations of Lipidomes in Rat Photoreceptor Degeneration Induced by N-Methyl-N-nitrosourea

To investigate alterations of lipidomes in the progress of photoreceptor degeneration induced by N-methyl-N-nitrosourea (MNU) in a rat model, retinal lipid molecular species in adult Sprague-Dawley (SD) rats at 1, 3, and 7 days after MNU administration and age-matched controls were analyzed by the shotgun lipidomics technology. Moreover, total fatty acid levels in retinal, liver, and plasma samples of different groups were determined with gas chromatography. Generally, at day 1, the levels of ethanolamine plasmalogen species in retinas were markedly elevated after treatment with MNU, while the contents of other phospholipids and sphingolipids in the retina were not significantly changed than those of the control group. The compositions of almost all of unsaturated fatty acids in the retina increased significantly at day 1 after MNU administration. At day 7, the MNU treatment group has significant increases in lipid species in the retina. However, the majority of lipids containing docosahexaenoic acid (DHA, 22:6n-3) and docosapentaenoic acid (22:5n-6) declined, especially di-DHA phospholipids were dramatically reduced in the retina. In contrast, similar alterations did not occur in plasma or the liver after MNU treatment. These results suggested that at the early stage of photoreceptor degeneration, lipidome remodeling in the retina might involve protection of photoreceptor from apoptosis and continue their transduction of light. However, at the late stage of photoreceptor apoptosis, increases in comprehensive lipid species occurred, likely due to the myelination of the retina. Finally, the deficiency of DHA in photoreceptor degeneration could exacerbate the influence of myelination on retinal function. We further investigated the effects of unsaturated fatty acids on neuronal apoptosis. The preliminary experiments confirmed our observation from lipidomics analysis that unsaturated fatty acids can protect neurons from apoptosis. Collectively, our study suggests that increased levels of DHA should be protective from photoreceptor degeneration.

Plasma fatty acids and primary open-angle glaucoma in the elderly: the Montrachet population-based study

Background

To compare plasma fatty acids (FAs) between participants with primary open-angle glaucoma (POAG) and participants without neuropathy in an elderly population and to investigate specific FAs pattern in POAG.

Methods

We conducted a population-based study in participants older than 75 years. Participants underwent a comprehensive eye examination with optic nerve photographs, visual field test and optic nerve OCT with RNFL thickness measurement. Glaucomatous status was defined according to the International Society for Epidemiologic and Geographical Ophthalmology classification. Lipids were extracted from plasma and FAs methylesters prepared and analyzed by gas chromatography-mass spectrometry.

Results

Among the 1153 participants of the Montrachet study 810 were retained for analysis and 68 had POAG. The mean age was 82.11 ± 3.67. In multivariable analysis FAs levels were not different between POAG participants and controls (P = 0.078). A FAs pattern characterized by high negative weight of gamma-linoleic acid, eicosapentaenoic acid polyunsaturated FAs (PUFAs), Cis-7 hexadecenoic acid monounsaturated FAs (MUFAs) and high positive weight of eicosadienoic acid, docosatetraenoic acid, docosapentaenoic n-6, alpha linoleic acid PUFAs, eicosenoic acid MUFAs, margaric acid and behenic acid saturated FAs was positively associated with POAG. After adjustment for major confounders, individuals in the upper tertile of FAs pattern scores compared with those in the lower tertile were more likely to present POAG (OR = 3.09 [95% CI 1.29–7.40] P = 0.013).

Conclusions

We found no significant difference regarding isolated plasma FAs between participants with POAG and participants without neuropathy in elderly but specific FAs pattern might be associated with POAG.

Antioxidant Activity and Neuroprotective Role of Docosahexaenoic Acid (DHA) Supplementation in Eye Diseases That Can Lead to Blindness: A Narrative Review

The objective of this narrative review is to provide updated evidence, based on data from experimental and clinical studies, of the prominent role of omega-3 polyunsaturated fatty acids (n-3 PUFAs) for a number of crucial mechanisms involved in counteracting cell damage induced by oxidative stress in eye diseases. This article is focused on the antioxidant and neuroprotective effects of docosahexaenoic acid (DHA), which have been assessed in different experimental models and clinical studies, particularly in proliferative diabetic retinopathy, age-related macular degeneration and glaucoma that are the most common eye diseases leading to severe vision loss. The mechanisms involved in the role of DHA in protecting human retinal pigment epithelial cells from oxidative stress as well as the interaction with glutathione (GSH) are also described. The review is intended to provide novel and salient findings supporting the rationale of the use of dietary supplementation with high-dose DHA (1050 mg/day) in the form of triglyceride as a potent antioxidant compound for improving the eye health. However, the overall clinical evidence for the use of dietary strategies based on supplementation with n-3 PUFAs in eye diseases linked to oxidative stress other than high-dose DHA triglyceride is both limited and inconsistent.

Identification of critical genetic variants associated with metabolic phenotypes of the Japanese population

We performed a metabolome genome-wide association study for the Japanese population in the prospective cohort study of Tohoku Medical Megabank. By combining whole-genome sequencing and nontarget metabolome analyses, we identified a large number of novel associations between genetic variants and plasma metabolites. Of the identified metabolite-associated genes, approximately half have already been shown to be involved in various diseases. We identified metabolite-associated genes involved in the metabolism of xenobiotics, some of which are from intestinal microorganisms, indicating that the identified genetic variants also markedly influence the interaction between the host and symbiotic bacteria. We also identified five associations that appeared to be female-specific. A number of rare variants that influence metabolite levels were also found, and combinations of common and rare variants influenced the metabolite levels more profoundly. These results support our contention that metabolic phenotyping provides important insights into how genetic and environmental factors provoke human diseases.

Effect of dietary modification and antioxidant supplementation on intraocular pressure and open-angle glaucoma

Primary open-angle glaucoma (POAG) is an age-dependent, intraocular pressure (IOP)-related degeneration of the retinal ganglion cells (RGC). At present, IOP is the only modifiable factor that has been identified to prevent glaucomatous vision loss. Though the pathogenesis of glaucomatous optic neuropathy is still not well understood, increasing evidence suggests oxidative stress may contribute to the induction and progression of glaucoma. Furthermore, antioxidant use may be protective against glaucoma through various mechanisms, including reducing IOP, preserving vascular health, and preventing ganglion cell loss. This article provides a comprehensive review of the effect of oxidative stress, diet, and antioxidant therapy on IOP and open-angle glaucoma.

Effect of an oral supplementation with a formula containing R-lipoic acid in glaucoma patients

OBJECTIVE

To analyse the safety and effectiveness of the oral administration of a commercialised supplement containing R-alpha lipoic acid, taurine, vitamins C and E, lutein, zeaxanthin, zinc, copper and docosahexaenoic acid, in patients with primary open angle glaucoma (POAG), and in control subjects.

MATERIAL AND METHODS

A prospective study of cases and controls was carried out, including 30 participants of both genders that were divided into: POAG Group (n=15) and a control group (CG; n=15), assigned to the oral intake of NuaDHA preparations Vision® (1 pill/day)+NuaDHA 1000 (2 pills/day) for 6 months. Participants were interviewed, ophthalmologically examined, and peripheral blood was taken for routine analysis and the determination of the pro-oxidant (malondialdehyde) and total antioxidant status. Statistical analysis was performed using the SPSS 22.0 program.

RESULTS

After 6 months of supplementation, there was a significant increase in the plasma total antioxidant status (1.073±0.090mM vs 1.276±0.107mM, P=.028), along with a parallel decrease in malondialdehyde (7.066±1.070μM vs 2.771±0.462μM, P=.005) in the POAG group. The malondialdehyde also decreased in the control group (6.17±1.336 vs. 2.51±0.391, P=.028). The Schirmer test improved (20-30%) and the subjective dry eye signs/symptoms noticeably decreased in the POAG group versus the CG.

CONCLUSIONS

Formulations containing antioxidant vitamins, R-alpha lipoic acid and docosahexaenoic acid, administered for 6 consecutive months, counteracted the oxidative stress by further stabilising the morphological/functional parameters of both the ocular surface and the glaucoma, without presenting with adverse effects or intolerances.

Association of Dietary Fatty Acid Intake With Glaucoma in the United States

Importance

Identifying whether an association exists between daily dietary polyunsaturated fatty acid (PUFA) consumption and the prevalence of glaucoma in the United States may provide modifiable dietary risk factors for the development of glaucoma.

Objective

To analyze the association between glaucoma and daily dietary intake of PUFAs, including ω-3 fatty acids, in the US population.

Design, Setting, and Participants

Data from 3865 participants in the National Health and Nutrition Examination Survey (NHANES) 2005-2008 database who were 40 years or older, had participated in the vision health and dietary intake questionnaires, and had available results from laboratory tests and eye examinations that included frequency-doubling technology visual field loss detection tests and optic disc photographs were included. Data collection was performed by NHANES from 2005 to 2006. Data for the present study were downloaded from their database May 1 to 30, 2017. Data analyses were performed from June 1 to October 1, 2017.

Exposures

Daily dietary intake of PUFAs, including ω-3 fatty acids.

Main Outcomes and Measures

Prevalence of glaucoma in the United States as defined using the Rotterdam criteria, which included a combination of optic cupping or asymmetry and visual field defect results.

Results

Of the 83 643 392 weighted survey participants included in this cross-sectional study, 43 660 327 (52.2%) were women and 3 076 410 (3.7%) met our criteria for having glaucoma. Compared with participants without glaucoma, those with glaucoma were older (mean [SE] age, 61.4 [0.8] vs 53.7 [0.4] years; P < .001). Increased levels of daily dietary intake of eicosapentaenoic acid (odds ratio [OR], 0.06; 95% CI, 0.00-0.73) and docosahexaenoic acid (OR, 0.06; 95% CI, 0.01-0.87) were associated with significantly lower odds of having glaucoma. However, participants with daily total dietary PUFA intake levels in the second (OR, 2.84; 95% CI, 1.39-5.79) and third (OR, 2.97; 95% CI, 1.08-8.15) quartiles showed significantly increased odds of meeting our criteria for a diagnosis of glaucoma.

Conclusions and Relevance

Increased daily dietary consumption levels of eicosapentaenoic acid and docosahexaenoic acid were associated with lower likelihood of glaucomatous optic neuropathy. However, consumption levels of total PUFAs in the higher quartiles were associated with a higher risk of glaucoma, which may have resulted from the relative intakes of ω-6 and ω-3 fatty acids and other confounding comorbidities. This study also hypothesizes that increasing the proportion of dietary ω-3 consumption levels while controlling overall daily PUFA intake may be protective against glaucoma. However, longitudinal studies or randomized clinical trials are needed to assess these hypotheses.

Effects of Fish n-3 PUFAs on Intestinal Microbiota and Immune System

Studies over several decades have documented the beneficial actions of n-3 polyunsaturated fatty acids (PUFAs), which are plentiful in fish oil, in different disease states. Mechanisms responsible for the efficacy of n-3 PUFAs include: (1) Reduction of triglyceride levels; (2) anti-arrhythmic and antithrombotic effects, and (3) resolution of inflammatory processes. The human microbiota project and subsequent studies using next-generation sequencing technology have highlighted that thousands of different microbial species are present in the human gut, and that there has been a significant variability of taxa in the microbiota composition among people. Several factors (gestational age, mode of delivery, diet, sanitation and antibiotic treatment) influence the bacterial community in the human gastrointestinal tract, and among these diet habits play a crucial role. The disturbances in the gut microbiota composition, i.e., gut dysbiosis, have been associated with diseases ranging from localized gastrointestinal disorders to neurologic, respiratory, metabolic, ocular, and cardiovascular illnesses. Many studies have been published about the effects of probiotics and prebiotics on the gut microbiota/microbioma. On the contrary, PUFAs in the gut microbiota have been less well defined. However, experimental studies suggested that gut microbiota, n-3 PUFAs, and host immune cells work together to ensure the intestinal wall integrity. This review discussed current evidence concerning the links among gut microbiota, n-3 PUFAs intake, and human inflammatory disease.

Effects of Oral Supplementation with Docosahexaenoic Acid (DHA) plus Antioxidants in Pseudoexfoliative Glaucoma: A 6-Month Open-Label Randomized Trial

PURPOSE

To assess the effects of antioxidant oral supplementation based on docosahexaenoic acid (DHA) in pseudoexfoliative (PEX) glaucoma.

PATIENTS AND METHODS

A prospective 6-month open-label randomized controlled trial was conducted in patients with PEX glaucoma and adequate intraocular pressure (IOP) control. Patients in the DHA group received a high-rich DHA (1 g) nutraceutical formulation. Ophthalmological examination, DHA erythrocyte membrane content (% total fatty acids), plasma total antioxidant capacity (TAC), plasma malondialdehyde (MDA), and plasma IL-6 levels were assessed.

RESULTS

Forty-seven patients (DHA group 23, controls 24; mean age 70.3 years) were included. In the DHA group, the mean IOP in the right eye decreased from 14.7 [3.3] mmHg at baseline to 12.1 [1.5] mmHg at 6 months (P=0.01). In the left eye, IOP decreased from 15.1 [3.3] mmHg at baseline to 12.2 [2.4] mmHg at 6 months (P=0.007). DHA erythrocyte content increased in the DHA group, with significant differences versus controls at 3 months and 6 months (8.1% [0.9] vs. 4.4% [0.7]; P < 0.0001). At 6 months and in the DHA group only, TAC levels as compared with baseline increased significantly (919.7 [117.9] vs. 856.9 [180.3] µM copper-reducing equivalents; P=0.01), and both MDA (4.4 [0.8] vs. 5.2 [1.1] nmol/mL; P  =  0.02) and IL-6 (2.8 [1.3] vs. 4.7 [2.3] pg/mL; P=0.006) levels were lower than in controls.

CONCLUSIONS

Targeting pathophysiology mechanisms of PEX glaucoma by reducing oxidative stress and inflammation with a high-rich DHA supplement might be an attractive therapeutic approach. Despite the short duration of treatment, decrease in IOP supports the clinical significance of DHA supplementation.

The relation between dietary intake and glaucoma: a systematic review

PURPOSE

A common question of patients to their physician is what they can do themselves against glaucoma, except taking their daily medication. However, for ophthalmologists, it is often hard to give their patients an advice on their dietary intake. To help ophthalmologists in answering this question, an overview of the current scientific literature on the association of nutrients with glaucoma is presented.

METHODS

A comprehensive systematic review was conducted in which articles published up to September 2017 were identified in PubMed and reference lists. Nutrients were categorized into minerals and trace elements, nutrition with antioxidative properties and omega-fatty acids.

RESULTS

The literature search revealed a total of 407 articles of which a total of 46 met the inclusion criteria. Most of these articles studied the effect of nutrients on open-angle glaucoma. Many trace elements have been investigated in the literature, but the most interesting are selenium and iron (both may increase the risk of glaucoma). Investigated nutrients with antioxidative properties and omega-fatty acids included glutathione, nitric oxide, carotenoids, flavonoids, and omega-3 and omega-6 fatty acids. Of these, glutathione, nitric oxide, and flavonoids had a significant protective effect on glaucoma.

CONCLUSION

Intake of selenium and iron may increase the risk of glaucoma, though, only few studies have been done on this topic. Nitric oxide present in other dark green leafy vegetables seems to have a beneficial effect on glaucoma. However, the evidence for an association of dietary intake with glaucoma is still not strong. More (longitudinal and randomized clinical trials) studies are required to make the presented findings clinically applicable.

Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults

PURPOSE

Elevated intraocular pressure (IOP) is the major modifiable risk factor for the sight-threatening eye disease, glaucoma. We investigated whether oral omega-3 supplements affect IOP in normotensive adults.

METHODS

We undertook a pooled analysis of data from two double-masked, placebo-controlled randomized trials (Australian New Zealand Clinical Trials Registry, ACTRN12614001019695, ACTRN12615000173594) that investigated the efficacy and safety of oral omega-3 supplementation for treating ocular surface inflammation. Recruitment involved adults (n = 105) with IOP <21 mm Hg, and without a current or prior glaucoma diagnosis. Participants were randomly allocated to either an oral omega-3 (∼1000 mg/day eicosapentaenoic acid + ∼500 mg/day docosahexaenoic acid ± 900 mg/day α-linolenic acid) or placebo (olive oil, 1500 mg/day) supplement. IOP was quantified at baseline and after 3 months of supplementation (day 90). Change in IOP, relative to baseline, was compared between groups.

RESULTS

At baseline, participants were of similar age (omega-3/placebo groups: mean ± SEM, 33.7 ± 1.7, n = 72/35.6 ± 3.0 years, n = 33), sex (65%/79% female), and had similar IOP (14.3 ± 0.3/13.8 ± 0.5 mm Hg). At day 90, IOP was reduced to 13.6 ± 0.3 mm Hg in the omega-3 group; controls had a slight IOP increase to 14.2 ± 0.4 mm Hg (P < 0.05).

CONCLUSIONS

Oral omega-3 supplementation for 3 months significantly reduced IOP in normotensive adults. To our knowledge, this is the first study to report that omega-3 fatty acids lower IOP in humans.

TRANSLATIONAL RELEVANCE

These findings justify further investigation into the therapeutic potential of omega-3 supplementation for reducing IOP, to prevent and/or treat conditions with IOP elevation, including ocular hypertension and glaucoma.

The Effect of Vitamins on Glaucoma: A Systematic Review and Meta-Analysis

Background: The aim of is to determine the association of vitamins with glaucoma by performing a systematic review and meta-analyses. Methods: Studies on the relation of vitamins and glaucoma published up to December 2017 were identified in the PubMed and Embase database. Data on vitamins (method of assessment), glaucoma (type and method of assessment), study characteristics and quality were recorded. In case of multiple studies for one nutrient a meta-analysis was performed. Results: A total of 629 articles were identified of which 36 were included in the systematic review. The meta-analysis included five of them (940 open-angle glaucoma (OAG) cases and 123,697 controls in total) and resulted in an odds ratio [95% confidence interval] (OR [95% CI]) of 0.58 [0.37–0.91] for dietary vitamin A, though heterogeneity was high (I² = 51%). After omitting studies that contributed significantly to the heterogeneity, the pooled OR [95% CI] was 0.45 [0.30–0.68] for dietary vitamin A on OAG (I² = 0%). For vitamin B1, C and E no significant association with OAG was found (OR [95% CI]: 0.84 [0.47–1.51]; 0.68 [0.38–1.22]; 0.95 [0.75–1.19]; respectively). However, after addressing heterogeneity, vitamin C showed a protective effect as well. Especially, foods high in these vitamins (e.g., dark green vegetables) were protective for OAG. Conclusions: Dietary intake of vitamin A and C showed a beneficial association with OAG; however, findings on blood levels of vitamins do not show a clear relation with OAG.

The Role of Diet in Glaucoma: A Review of the Current Evidence

Intraocular pressure (IOP) reduction by medications, laser, or surgery remains the mainstay of treatment in glaucoma. However, the role of complementary and alternative medicine (CAM) in glaucoma has received great interest from both patients and ophthalmologists. Previous evidence suggests that diet, a major domain of CAM, can influence an individual's IOP level. Furthermore, certain dietary components have been linked to the incidence and progression of glaucoma. In this review, we aim to provide a summary of the current evidence regarding the role of obesity, certain dietary components, and dietary supplements in glaucoma.

Lifestyles guide and glaucoma (II). Diet, supplements, drugs, sleep, pregnancy, and systemic hypertension

PURPOSE

To establish evidence based guidelines to advise patients on the relationship between habits, diet, certain circumstances, diseases and glaucoma.

METHODS

Review of all published articles on glaucoma and sports or other activities. The papers were classified according to the level of scientific evidence based on the Oxford Centre for Evidence-based Medicine classification.

RESULTS

The evidence on the relationship between diet or supplements and the incidence or progression of glaucoma is insufficient to make a general recommendation for glaucoma patients. Although some studies on normal tension glaucoma suggest that Gingko biloba could reduce glaucoma progression, the results do not allow a general recommendation for all these patients. Similarly, the evidence on the usefulness of vitamin supplements is not conclusive. The studies on smoking do not clearly demonstrate the relationship between this habit and incidence of glaucoma. Marihuana is not a useful treatment for glaucoma. Although the results on the relationship between sleep apnoea and glaucoma are heterogeneous, it is recommended that patients with moderate to intense apnoea are tested for glaucoma. Pregnancy does not influence the course of the disease, but several hypotensive drugs may be harmful for the foetus. Nocturnal systemic hypotension is a risk factor for glaucoma progression.

CONCLUSIONS

Certain habits, circumstances, or diseases may have an influence on the onset or progression of glaucoma. It is important to have adequate information about the scientific evidence in the publications in order to properly advise patients.

Omega-3 fatty acids protect retinal neurons in the DBA/2J hereditary glaucoma mouse model

The purpose of this study was to evaluate the neuroprotective effects of omega-3 polyunsaturated fatty acid (ω3-PUFA) supplementation, alone or in combination with timolol eye drops, in a mouse model of hereditary glaucoma. DBA/2J mice (8.5-month-old) were assigned to an ω3-PUFAs + timolol, ω3-PUFAs only, timolol only, or an untreated group. Treated mice received a daily gavage administration of eicosapentaenoic acid (EPA) and docosahexaenoic acid and/or topical instillation of timolol (0.5%) once a day for 3 months. Blood was analysed regularly to determine ω3-PUFA levels and retinas were histologically analysed. Real-time PCR and Western blot were performed for retinal pro-inflammatory cytokines and macrophages. Blood arachidonic acid/EPA ratio gradually decreased and reached the desired therapeutic range (1-1.5) after 4 weeks of daily gavage with ω3-PUFAs in the ω3-PUFAs + timolol and ω3-PUFAs only groups. Retinal ganglion cell densities were significantly higher in the ω3-PUFAs + timolol (1303.77 ± 139.62/mm²), ω3-PUFAs only (768.40 ± 52.44/mm²) and timolol only (910.57 ± 57.28/mm²) groups than in the untreated group (323.39 ± 95.18/mm²). ω3-PUFA supplementation alone or timolol alone, significantly increased protein expression levels of M1 macrophage-secreted inducible nitric oxide synthase and M2 macrophage-secreted arginase-1 in the retina, which led to significant decreases in the expression levels of tumour necrosis factor-α (TNF-α). ω3-PUFA supplementation alone also resulted in significantly reduced expression of interleukin-18 (IL-18). ω3-PUFA + timolol treatment had no effect on the expression level of any of the aforementioned mediators in the retina. Supplementation with ω3-PUFAs has neuroprotective effect in the retinas of DBA/2J mice that is enhanced when combined with timolol eye drops. The continued inflammation following ω3-PUFAs + timolol treatment suggests that downregulation of IL-18 and TNF-α may not be the only factors involved in ω3-PUFA-mediated neuroprotection in the retina.

Association of fatty acid-binding protein 2 and fat mass and obesity-associated gene polymorphism with primary open-angle glaucoma

PURPOSE:

The present study was carried out to investigate the association of fatty acid-binding protein 2 (FABP2) and fat mass and obesity-associated (FTO) gene polymorphism with primary open-angle glaucoma (POAG) cases and controls.

MATERIALS AND METHODS:

This study includes 122 POAG cases and 112 controls. FABP2 and FTO gene polymorphisms in cases and controls were evaluated by polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS:

The mean ages were 49.88 ± 12.34 and 53.74 ± 11.87 years in POAG cases and control groups, respectively. The FABP2 gene AA, AT, TT genotype frequencies were 12.90%, 62.40%, 24.80% in POAG cases and 20.60%, 64.70%, 14.70% in healthy controls, respectively. The frequencies of A and T allele in POAG cases were 44.06% and 55.94% as compared to 52.94% and 47.06% in the controls. The FTO gene AA, AT, TT genotype frequencies were 2.00%, 79.20%, 18.80% in cases and 0%, 75.50%, 24.50% in healthy controls, respectively. The frequencies of A and T allele in POAG cases were 41.58% and 58.42% as compared to 37.75% and 62.25% in the controls. No significant difference in the frequencies of FABP2 and FTO genotype was found between POAG cases and controls.

CONCLUSION:

We could not identify the possible association of FABP2 and FTO gene polymorphism with POAG; however, further studies with larger sample size in different population are require to clarify the role of FABP2 and FTO genes in susceptibility to POAG.

Metabolome-Wide Association Study of Primary Open Angle Glaucoma

PURPOSE

To determine if primary open-angle glaucoma (POAG) patients can be differentiated from controls based on metabolic characteristics.

METHODS

We used ultra-high resolution mass spectrometry with C18 liquid chromatography for metabolomic analysis on frozen plasma samples from 72 POAG patients and 72 controls. Metabolome-wide Spearman correlation was performed to select differentially expressed metabolites (DEM) correlated with POAG. We corrected P values for multiple testing using Benjamini and Hochberg false discovery rate (FDR). Hierarchical cluster analysis (HCA) was used to depict the relationship between participants and DEM. Differentially expressed metabolites were matched to the METLIN metabolomics database; both DEM and metabolites significantly correlating with DEM were analyzed using MetaboAnalyst to identify metabolic pathways altered in POAG.

RESULTS

Of the 2440 m/z (mass/charge) features recovered after filtering, 41 differed between POAG cases and controls at FDR = 0.05. Hierarchical cluster analysis revealed these DEM to associate into eight clusters; three of these clusters contained the majority of the DEM and included palmitoylcarnitine, hydroxyergocalciferol, and high-resolution METLIN matches to sphingolipids, other vitamin D-related metabolites, and terpenes. MetaboAnalyst also indicated likely alteration in steroid biosynthesis pathways.

CONCLUSIONS

Global ultrahigh resolution metabolomics emphasized the importance of altered lipid metabolism in POAG. The results suggest specific metabolic processes, such as those involving palmitoylcarnitine, sphingolipids, vitamin D-related compounds, and steroid precursors, may contribute to POAG status and merit more detailed study with targeted methods.

Oxidative stress and mitochondrial failure in the pathogenesis of glaucoma neurodegeneration

This review focuses on oxidative stress and mitochondrial failure for understanding mechanisms of optic nerve damage in primary open-angle glaucoma. The chapter shows scientific evidence for the role of mitochondrial disbalance and reactive oxygen species in glaucoma neurodegeneration. Mitochondria regulate important cellular functions including reactive oxygen species generation and apoptosis. Mitochondrial alterations result from a wide variety of damaging sources. Reactive oxygen species formed by the mitochondria can act as signaling molecules, inducing lipid peroxidation and/or excitotoxicity with the result of cell lesion and death. Antioxidants may help to counteract oxidative stress and to promote neuroprotection. We provide information that may lead to a new way for diagnosing and treating glaucoma patients.

A two-year follow-up of oral antioxidant supplementation in primary open-angle glaucoma: an open-label, randomized, controlled trial

PURPOSE

To evaluate the effect of oral antioxidant supplementation (OAS) on primary open-angle glaucoma (POAG) over a 2-year follow-up period.

PATIENTS AND METHODS

In this open-label, randomized controlled trial, 117 eyes of 117 patients with mild or moderate POAG and intraocular pressure under control with topical antiglaucoma medications were recruited and randomly divided into three groups according to supplementation: (1) OAS with (ICAPS R(®) - Alcon Laboratories, n = 26); (2) OAS without ω-3 fatty acids (OFTAN MACULA(®) - Laboratorios Esteve, n = 28); and (3) a control group without OAS (n = 63). They all underwent visual field (VF) tests (Humphrey 24-2) and scans using a Fourier-domain optical coherence tomography (FD-OCT) device (RTVue-100) at the beginning of the study and 2 years later. Mean deviation (MD), standard pattern deviation (PSD), peripapillary retinal nerve fibre layer (RNFL) and macular ganglion cell complex (GCC) parameters were considered for the analysis. Patients were also classified according to MD deterioration (fast deterioration vs. slow deterioration).

RESULTS

Visual field global indices, peripapillary RNFL thickness and macular GCC thickness showed no differences among the groups at the beginning and end of the follow-up. Besides all the comparisons among groups for differences before and after the follow-up of the MD, PSD, RNFL and GCC parameters were also non-significant. The proportions of patients according to MD deterioration were similar among the groups and subgroups (p > 0.05 for all the comparisons).

CONCLUSION

Oral antioxidant supplementation with or without ω-3 fatty acids does not appear useful as an adjuvant treatment of mild/moderate POAG in the short term.

Association of n3 and n6 polyunsaturated fatty acids in red blood cell membrane and plasma with severity of normal tension glaucoma

AIM

To determine whether red blood cell (RBC) membrane and plasma lipids, particularly long-chain polyunsaturated fatty acids such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) are significantly correlated with severity of normal tension glaucoma (NTG).

METHODS

This study included 35 patients with NTG and 12 healthy normal control subjects, matched for age and sex with the study group. The stage of glaucoma was determined according to the Hodapp-Parrish-Anderson classification. Lipids were extracted from RBC membranes and plasma, and fatty acid methyl esters prepared and analyzed by gas chromatography-mass spectrometry (GC-MS).

RESULTS

When RBC lipids were analyzed, the levels of EPA, the levels of DHA and the ratio of n3 to n6 were positively associated with the Humphrey Perimetry mean deviation (MD) score (r=0.617, P<0.001; r=0.727, P<0.001 and r=0.720, P<0.001, respectively), while the level of AA was negatively associated with the MD score (r=-0.427, P=0.001). When plasma lipids were analyzed, there was a significant positive relationship between the levels of EPA and the MD score (r=0.648, P<0.001), and the levels of AA were inversely correlated with the MD score (r=-0.638, P<0.001).

CONCLUSION

The levels of n3 and n6 polyunsaturated fatty acids in RBC membrane and plasma lipids were associated with severity of NTG.

Essential fatty acids in the treatment of dry eye syndrome: A myth or reality?

Dry eye is a common condition that can severely impair the quality of life. Systemic and topical omega-3 fatty acids and omega-6 fatty acids have been used as treatment for patients with dry eye disease and showed promising results. Further multicenter randomized controlled trials are required in order to establish a standardized protocol for the treatment of dry eye syndrome with those essential fatty acids.

Phospholipid profiles of control and glaucomatous human aqueous humor

To compare phospholipid (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol) profiles of human control and glaucomatous aqueous humor (AQH). AQH samples were procured during surgery from human POAG and control subjects (n = 15 each). Samples were used following institutional review board approved protocols and adhering to the tenets of the Declaration of Helsinki. Lipid extraction was performed using a modification of the Bligh and Dyer method, protein concentrations were determined using the Bradford's method, and select samples were confirmed with Densitometry of PHAST gels. Lipids were identified and subjected to ratiometric quantification using a TSQ Quantum Access Max triple quadrupole mass spectrometer utilizing precursor ion scan (PIS) or neutral ion loss scan (NLS) using appropriate class specific lipid standards in a two step quantification process. The comparative profiles of phosphatidylcholines, phosphatidylserines, phosphatidylethanolamines and phosphatidylinositols between control and glaucomatous AQH showed several species common between them. A number of unique lipids in all four phospholipid classes were also identified in control eyes that were absent in glaucomatous eyes and vice versa. A number of phospholipids were found to be uniquely present in control, but absent in glaucomatous AQH and vice versa. Compared with a previous study of control and POAG red blood cells, a number of these phospholipids are absent locally (AQH).

Biomarkers of primary open-angle glaucoma

Primary open-angle glaucoma (POAG) is a primary neuronal disease of the optic nerve without a definable cause, and is often associated with increased intraocular pressure. Worldwide, POAG is the second leading cause of blindness; there are 45 million people today with POAG and bilateral blindness is present in 4.5 million of these. In order to elucidate the possible etiologic factors in POAG, we have cataloged all known biomarkers in the aqueous humor, trabecular meshwork, optic nerve and blood into four categories, namely extracellular matrix (ECM), cell signaling molecules, aging/stress and immunity-related changes. We present a theoretical model to show possible signaling pathways of the ECM, cell signaling and innate immune response through activation of Toll-like receptor 4. Our article suggests that ECM and innate immune biomarkers are the lead candidates for developing the 'POAG biomarker signature'. We suggest that current research is critical to pinpoint the causes of the disease so that new treatment modalities can become available for better regulation of the intraocular pressure and neuroprotection of the optic nerve.

Omega 3:6 ratio intake and incidence of glaucoma: the SUN cohort

BACKGROUND & AIMS

Omega 3 and omega 6 polyunsaturated fatty acids have been related to many diseases, especially to cardiovascular diseases. We aimed to assess the association between the intake of omega 3, omega 6 fatty acids and their ratio and the incidence of glaucoma in this prospective cohort study.

METHODS

We followed-up 17,128 participants initially free of glaucoma for a median time of 8.2 years. Validated data of diet were collected at baseline with a 136-item semi-quantitative food-frequency questionnaire and information of new diagnosis of glaucoma in biennial follow-up questionnaires. Multivariable Cox regression models were fit to assess the relationship between omega 3, omega 6 and their ratio and the incidence of glaucoma in the total sample and in participants aged ≥40 years at baseline.

RESULTS

During a median follow-up time of 8.2 years, 156 new cases of glaucoma were identified. No significant association was observed for the omega 3 or the omega 6 intake and the risk of glaucoma. Participants in the highest quintile of omega 3:6 ratio intake had a significantly higher risk of glaucoma than participants in the lowest quintile (hazard ratio (HR): 1.91 [95%CI: 1.05-3.46], p for trend 0.03). The association became stronger (HR for the comparison of the 5th versus the 1st quintile: 2.43 [95%CI: 1.17-5.03], p for trend 0.02) when we considered only those participants who were ≥40 years old.

CONCLUSIONS

Our data suggest an association between omega 3:6 ratio intake and incident glaucoma in our cohort, especially among older participants.

Nutritional, lifestyle and environmental factors in ocular hypertension and primary open-angle glaucoma: an exploratory case-control study

PURPOSE

To evaluate known and potential risk factors, including nutritional, lifestyle and environmental factors, differentiating patients with high-tension primary open-angle glaucoma (POAG) from control subjects with ocular hypertension (OHT).

METHODS

In 2006-2007, 111 French ophthalmologists prospectively enrolled 339 cases of POAG and 339 age-matched controls with OHT. After a clinical examination with assessment of ocular risk factors, the ophthalmologist filled, during face-to-face interview, a detailed questionnaire developed by nutritionists and epidemiologist on lifestyle and environmental risk factors, including socio-demographic variables, dietary habits related to omega-3 fatty acids intake, smoking and alcohol drinking and professional exposure to pesticides and other chemicals. Associations of POAG with risk factors were estimated using conditional logistic regression, with adjustment for age, gender and duration of disease.

RESULTS

In the final multivariate model, by comparison with OHT, POAG was significantly associated with more frequent use of pesticides during the professional life [OR = 2.65, 95% confidence interval (CI): 1.04-6.78, p = 0.04] and with low consumption of fatty fish (OR = 2.14, 95% CI: 1.10-4.17, p = 0.02) and walnuts (OR = 2.02, 95% CI: 1.18-3.47, p = 0.01). POAG was also associated with higher frequency of heavy smoking (40 pack-years or more, OR = 3.93, 95% CI: 1.12-13.80, p = 0.03) but not with moderate (20-40 pack-years) and light smoking (<20 pack-years).

CONCLUSIONS

These exploratory observations suggest a protective effect of omega-3 fatty acids and a deleterious effect of heavy smoking and professional exposure to pesticides in POAG. This will need to be confirmed in future studies.

Dietary ω-3 deficiency and IOP insult are additive risk factors for ganglion cell dysfunction

AIM

Dietary deficiencies in ω-3 polyunsaturated fatty acids are known to effect retinal function including retinal ganglion cell (RGC) activity, which may have implications for glaucoma. In this study we consider retinal function after dietary manipulation and intraocular pressure (IOP) stress designed to compromise RGCs.

METHODS

Sprague-Dawley dams were fed either ω-3 sufficient (ω-3, n=15) or deficient (ω-3, n=16) diets 5 weeks before conception with pups subsequently weaned onto their mothers diets. At 20 weeks of age, acute IOP elevation was induced repeatedly through anterior chamber cannulation to 70 mm Hg for 1 hour on 3 separate occasions separated by 1 week. Electroretinograms were recorded 1 week after each IOP elevation to assay the photoreceptors (PIII), ON-bipolar cells (PII), and ganglion/amacrine cells (STR).

RESULTS

Repeat IOP insult results in a specific RGC dysfunction (pSTR -14.5%, P<0.035) as does ω-3 deficiency (-26.4%, P<0.01). However, the combination of both causes an even larger RGC functional loss (-40.1%, P<0.001) than does either diet or IOP insult in isolation (P<0.001).

CONCLUSIONS

Both ω-3 deficiency and repeat acute IOP insult cause RGC dysfunction and the combination of these factors results in a cumulative effect. Our data indicate that sufficient dietary ω-3 improves RGC function making it less susceptible to IOP insult.

Patients undergoing long-term treatment with antihypertensive eye drops responded positively with respect to their ocular surface disorder to oral supplementation with antioxidants and essential fatty acids

Background

Glaucoma and dry eye disorders (DEDs) are frequent comorbidities. The antioxidant and anti-inflammatory properties of essential polyunsaturated fatty acids have been extensively studied in relation to eye diseases.

Objective

Our objective was to determine the effects of oral supplementation with a combined formulation of antioxidants and essential polyunsaturated fatty acids on expression of cytokines and chemokines in tears from patients with DEDs or primary open-angle glaucoma (POAG).

Methods

Participants (n = 97) were distributed into three groups: (1) individuals with nonsevere DEDs (DEDG), (2) individuals with nonadvanced POAG (POAGG), and (3) healthy controls. These groups were randomized into two subgroups: one received a daily antioxidant and essential polyunsaturated fatty acid supplement (two pills) for 3 months (+S), and the other did not (−NS). Participants were interviewed and ophthalmologically examined. Concentrations of specific cytokines and chemokines in reflex tears were determined by multiplexed particle-based flow cytometry. The data were analyzed statistically (SPSS version 15.0).

Results

Comparison of the results from the DEDG and POAGG patients showed significant differences in tear expression of granulocyte-macrophage colony-stimulating factor (P = 0.008), tumor necrosis factor α (P = 0.005), vascular endothelial growth factor (P = 0.038), interleukin-4 (P = 0.030), and interleukin-6 (P = 0.044). The main signs and symptoms of dry eyes such as dryness, burning, photophobia, eye heaviness, and blurred vision, as well as positive changes in eyelashes, hair, nails and skin, were significantly improved in DEDG +S and POAGG +S patients relative to unsupplemented patients.

Conclusion

Inflammation biomarkers were differentially expressed in glaucomatous tears, but the differences changed upon antioxidant/essential polyunsaturated fatty acid supplementation. Chronic instillation of antihypertensive eye drops must be considered for integrating protocols to glaucoma standards of care.

Effects of a nutraceutical formulation based on the combination of antioxidants and ω-3 essential fatty acids in the expression of inflammation and immune response mediators in tears from patients with dry eye disorders

BACKGROUND

Women, and those older than 65 years of age, are particularly susceptible to dry eye disorders (DEDs). Inflammation is clearly involved in the pathogenesis of DEDs, and there is mounting evidence on the antioxidant and antiinflammatory properties of essential polyunsaturated fatty acids (EPUFAs).

OBJECTIVE

To analyze whether a combined formulation of antioxidants and long-chain EPUFAs may improve the evolution of DEDs.

METHODS

We used a prospective study to address the relationship between risk factors, clinical outcomes, and expression levels of inflammation and immune response (IIR) mediators in human reflex tear samples. Participants included: (1) patients diagnosed with nonsevere DEDs (DED group [DEDG]); and (2) healthy controls (control group [CG]). Participants were randomly assigned to homogeneous subgroups according to daily oral intake (+S) or not (-NS) of antioxidants and long-chain EPUFAs for 3 months. After an interview and a systematized ophthalmic examination, reflex tears were collected simultaneously from both eyes; samples were later subjected to a multiplexed particle-based flow cytometry assay. A specific set of IIR mediators was analyzed. All data were statistically processed through the SPSS 15.0 software program.

RESULTS

Significantly higher expressions of interleukin (IL)-1β, IL6, and IL10 and significantly lower vascular endothelial growth factor expressions were found in the DEDG as compared to the CG. In the DEDG, significant negative correlations were detected between the Schirmer test and IL-1β, IL6, IL8, and vascular endothelial growth factor levels, and between the fluorescein breakup time with IL6 and IL8 levels. However, levels of IL-1β, IL6, and IL10 in tears were significantly lower in the DEDG+S versus the DEDG-NS and in the CG+S versus the CG-NS. Subjective symptoms of dry eye significantly improved in the DEDG+S versus the DEDG-NS.

CONCLUSION

IIR mediators showed different expression patterns in DED patients, and these patterns changed in response to a combined formulation of antioxidant and EPUFAs supplementation. Our findings may be considered for future protocols integrating clinical/biochemical data to help manage DED patients.

Lipid composition of the human eye: are red blood cells a good mirror of retinal and optic nerve fatty acids?

BACKGROUND

The assessment of blood lipids is very frequent in clinical research as it is assumed to reflect the lipid composition of peripheral tissues. Even well accepted such relationships have never been clearly established. This is particularly true in ophthalmology where the use of blood lipids has become very common following recent data linking lipid intake to ocular health and disease. In the present study, we wanted to determine in humans whether a lipidomic approach based on red blood cells could reveal associations between circulating and tissue lipid profiles. To check if the analytical sensitivity may be of importance in such analyses, we have used a double approach for lipidomics.

METHODOLOGY AND PRINCIPAL FINDINGS

Red blood cells, retinas and optic nerves were collected from 9 human donors. The lipidomic analyses on tissues consisted in gas chromatography and liquid chromatography coupled to an electrospray ionization source-mass spectrometer (LC-ESI-MS). Gas chromatography did not reveal any relevant association between circulating and ocular fatty acids except for arachidonic acid whose circulating amounts were positively associated with its levels in the retina and in the optic nerve. In contrast, several significant associations emerged from LC-ESI-MS analyses. Particularly, lipid entities in red blood cells were positively or negatively associated with representative pools of retinal docosahexaenoic acid (DHA), retinal very-long chain polyunsaturated fatty acids (VLC-PUFA) or optic nerve plasmalogens.

CONCLUSIONS AND SIGNIFICANCE

LC-ESI-MS is more appropriate than gas chromatography for lipidomics on red blood cells, and further extrapolation to ocular lipids. The several individual lipid species we have identified are good candidates to represent circulating biomarkers of ocular lipids. However, further investigation is needed before considering them as indexes of disease risk and before using them in clinical studies on optic nerve neuropathies or retinal diseases displaying photoreceptors degeneration.

Cod liver oil: a potential protective supplement for human glaucoma

Glaucoma is one of the leading causes of visual impairment and blindness. Improved knowledge of the pathogenesis of this disease has allowed the exploration of new therapeutic methods. In general, elevated intraocular pressure (IOP), oxidative stress, and vascular insufficiency are accepted as the major risk factors for the progression of glaucoma. Many natural compounds have been found beneficial for glaucoma. Nutritional therapies are now emerging as potentially effective in glaucomatous therapy. One nutritional supplement with potential therapeutic value is cod liver oil, a dietary supplement that contains vitamin A and omega-3 polyunsaturated fatty acids (PUFAs). Vitamin A is important for preserving normal vision and it is a well-known antioxidant that prevents the oxidative damage that contributes to the etiology and progression of glaucoma. Vitamin A is also a crucial factor for maintaining the integrity of conjunctival and corneal ocular surfaces, and preventing the impairment of ocular epithelium caused by topical antiglaucomatous drugs. Omega-3 fatty acids are beneficial for glaucoma patients as they decrease IOP, increase ocular blood flow, and improve optic neuroprotective function. In this article, we propose that cod liver oil, as a combination of vitamin A and omega-3 fatty acids, should be beneficial for the treatment of glaucoma. However, further studies are needed to explore the relationship between cod liver oil and glaucoma.

Increased serum total antioxidant status and decreased urinary 8-hydroxy-2'-deoxyguanosine levels in patients with normal-tension glaucoma

PURPOSE

To investigate the amount of systemic oxidative stress-related DNA damage and serum total antioxidant status of patients with normal-tension glaucoma compared with healthy controls.

METHODS

Forty-three patients with normal-tension glaucoma selected from 60 consecutive newly diagnosed patients with primary open-angle glaucoma were enrolled. Each patient's intraocular pressure (IOP) was measured seven times over a 24-hour period. Those whose highest IOP was over 21 mmHg were excluded. Forty control subjects were recruited. The serum total antioxidant status was assessed colorimetrically by its ability to reduce the generation of the radical cation ABTS (2,2-azinobis-3-ethylbenzthiazoline sulphonate). The urinary 8-hydroxy-2'-deoxyguanosine was measured as a marker of oxidative DNA damage and normalized to creatinine. The results were compared between healthy subjects and patients with normal-tension glaucoma.

RESULTS

The control and normal-tension glaucoma groups did now show significant differences for age, gender, serum fructosamine, cholesterol and triglyceride levels; systolic and diastolic blood pressure, body mass index; and prevalence of hypertension. The serum total antioxidant status was significantly higher (p = 0.01) and the urinary 8-hydroxy-2'-deoxyguanosine/creatinine level significantly lower (p = 0.03) in the patients with normal-tension glaucoma compared with the controls. Even after we adjusted the data for independent variables, the incidence of normal-tension glaucoma was significantly correlated with high serum total antioxidant levels (p = 0.03; odds ratio, 1.007; 95% confidence interval, 1.001-1.013) and low urinary 8-hydroxy-2'-deoxyguanosine/creatinine (p = 0.02; odds ratio 0.76; 95% confidence interval, 0.61-0.96).

CONCLUSIONS

Increased serum total antioxidant and decreased 8-hydroxy-2'-deoxyguanosine may reflect compensatory alterations in response to increased systemic oxidative stress in patients with normal-tension glaucoma.

Genome-wide association study of normal tension glaucoma: common variants in SRBD1 and ELOVL5 contribute to disease susceptibility

PURPOSE

Factors contributing to the development of normal tension glaucoma (NTG), degenerative optic neuropathy characterized by the progressive loss of retinal ganglion cells, optic nerve axons, and visual fields, have not been determined. To identify genetic risk factors for NTG, we performed a genome-wide association study of NTG.

DESIGN

Case-control study.

PARTICIPANTS

The study cohort consisted of 305 Japanese patients with NTG and 355 controls.

METHODS

We genotyped 500,568 single-nucleotide polymorphisms (SNPs) and assessed the allelic diversity among cases and controls.

MAIN OUTCOME MEASURES

Genotypes of 500,568 SNPs.

RESULTS

The 2 most strongly NTG-associated SNPs, rs3213787 and rs735860, are located in an intron of SRBD1 and the 3'-untranslated region of ELOVL5 (P = 2.5 x 10(-9), odds ratio = 2.80 and P = 4.1 x 10(-6), odds ratio = 1.69), respectively. Real-time quantitative reverse transcription-polymerase chain reaction assays showed significantly increased expression of each gene in the white blood cells of subjects harboring the risk allele of these SNPs.

CONCLUSIONS

Our genome-wide association study identified SRBD1 and ELOVL5 as new susceptibility genes for NTG. Because SRBD1 and ELOVL5 are reportedly involved in the induction of cell growth inhibition or apoptosis, the regulation of SRBD1 and ELOVL5 cascades may play an important physiologic role in the risk of NTG development.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Serum free fatty acids levels not associated with normal tension glaucoma

Purpose:

To determine the free fatty acid levels in the sera of patients with normal-tension glaucoma and compare it with that of normal controls.

Methods:

Forty-four consecutive patients with newly diagnosed normal-tension glaucoma and forty-four age and gender matched controls were evaluated. The type and level of fatty acids in the sera were measured by gas chromatography (Model GC17A; Shimazu, Kyoto, Japan). Twenty-four fatty acids were identified from 12:0 to 24:1. The values were compared between the normal-tension glaucoma and control groups by Mann–Whitney U tests.

Results:

No statistically significant difference was found in the levels of any free fatty acids between the normal-tension glaucoma group and control group.

Conclusion:

No significant association was found in the serum free fatty acids levels including docosahexaenoic acid and eicosapentaenoic acid between normal-tension glaucoma patients and controls.

Analysis of Retina and Erythrocyte Glycerophospholipid Alterations in a Rat Model of Type 1 Diabetes

An automated tandem mass spectrometry based analysis employing precursor ion and neutral loss scans in a triple quadrupole mass spectrometer has been employed to identify and quantify changes in the abundances of glycerophospholipids extracted from retina and erythrocytes in a rat streptozotocin model of type 1 diabetes, 6 weeks and 36 weeks following induction of diabetes, compared to age matched nondiabetic controls. The utility of an 'internal standard' method compared to an 'internal standard free' method for quantification of differences in the abundances of specific lipid ions was evaluated in both retina and erythrocyte lipid extracts. In retina, equivalent results were obtained by using the internal standard and 'internal standard free' methods for quantification. In erythrocytes, the two methods of analysis yielded significantly different results, suggesting that factors intrinsic to particular sample types may influence the outcome of label-free lipidome quantification approaches.Overall increases (~25% to ~35%) in the abundances of major retina glycerophospholipid classes were demonstrated in rats at 6 weeks of diabetes, relative to control animals. However, at 36 weeks of diabetes, subsequent overall decreases in retina glycerophosphocholine and glycerophosphoethanolamine abundances of 16% and 33%, respectively, were observed. Additionally, retina and erythrocyte glycerophosphocholine lipids at both 6 week and 36 weeks of diabetes exhibited increased incorporation of linoleic acid((18:2n6)) and a decrease in docosahexaenoic acid (DHA((22:6n3))) content. Finally, an approximately 5-fold increase in the abundances of specific glycated glycerophosphoethanolamine (Amadori-GPEtn) lipids were observed in the retina of 36 week diabetic rats, with a corresponding 1.6 fold increase of Amadori-GPEtn lipids in diabetic erythrocytes.

Lifestyle, nutrition, and glaucoma

The only proven strategy to prevent primary open-angle glaucoma (POAG) is the use of ocular hypotensive therapy among people diagnosed with ocular hypertension. In this review, various modifiable lifestyle factors, such as exercise, diet, and cigarette smoking, that may influence intraocular pressure and that have been studied in relation to the risk of developing POAG are discussed. Epidemiologic studies on lifestyle factors are few, and the current evidence suggests that there are no environmental factors that are clearly associated with POAG; however, a few factors merit further study. This review also outlines future directions for research into the primary prevention of POAG.