Vitamin D Supplementation and the Incidence of Cataract Surgery in Older Australian Adults

Causal effect of the 25-Hydroxyvitamin D concentration on ocular diseases: A Mendelian randomization study

Observational studies report controversial associations between vitamin D levels and ocular diseases. We investigated the potential causal effect of 25-hydroxyvitamin D [25(OH)D] on ocular diseases using two-sample Mendelian randomization (MR). We examined associations between 25(OH)D and various ocular diseases including age-related macular degeneration, cataracts, diabetic retinopathy, myopia, glaucoma, conjunctivitis, keratitis and optic neuritis. Data were from genome-wide association studies of 25(OH)D and ocular diseases. We performed MR analyses using inverse-variance weighted methods with sensitivity analyses. We found no significant causal relationships between 25(OH)D and ocular diseases (all P > 0.05). Tests for heterogeneity (P > 0.05) and pleiotropy (P > 0.05) supported the MR validity. Our MR analysis does not provide evidence supporting a causal relationship between 25(OH)D and ocular disease risk in Europeans. This suggests that previous epidemiological associations may stem from shared biological factors or confounders rather than direct causality. However, further research is needed to fully elucidate the complex relationships between vitamin D and ocular health.

Association between vitamin D level and cataract: A systematic review and meta-analysis

PURPOSE

The association between serum vitamin D level and cataract remains controversial. This study aims to evaluate the association between vitamin D level and cataract.

METHODS

In this study, articles in the PubMed, Web of Science, and EMBASE databases were searched up to 30 August 2023 and 626 articles were screened. Four studies involving a total of 10,928 subjects with cataract and 10,117 control subjects met the inclusion criteria.

RESULTS

Decreased serum vitamin D level was associated with higher incidence of cataract (P = 0.047; MD: -4.87; 95%CI: [-9.67, -0.07]). In the subgroup analysis by sex, a significant association was found between serum vitamin D level and cataract in both male (P = 0.01, MD: -2.15,95%CI: [-3.83, -0.46]) and female (P < 0.01; MD: -6.67,95%CI: [-8.20, -5.14]).In the subgroup analysis by the types of cataract, significant association was found between serum vitamin D level and nuclear (P < 0.01; MD: -10.48; 95%CI: [-12.72, -8.24]) and posterior subcapsular cataract (P = 0.02; MD: -6.05; 95%CI: [-11.30, -0.80]) but not in cortical cataract (P = 0.14; MD: -6.74; 95%CI: [-15.70, 2.22]).

CONCLUSION

This meta-analysis revealed potential association between serum vitamin D level and cataract, more significant in female, and the subtypes of nuclear and posterior subcapsular cataract.

Predictive role of the peripheral blood inflammation indices neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immunoinflammatory index (SII) for age-related cataract risk

The novel inflammatory markers neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immunoinflammatory index (SII) have not yet been used in the study of age-related cataracts. The aim of this study was to investigate the possible relationships between the NLR, PLR, and SII and age-related cataracts. In the 2005-2008 National Health and Nutrition Examination Survey (NHANES) cross-sectional surveys, we collected complete information on blood counts, whether cataract surgery had been performed, and baseline information for adults. We investigated the independent interactions between the inflammatory markers NLR, PLR, and SII and age-related cataracts via weighted multivariate regression analyses and subgroup analyses. Smoothed curve fitting was performed to identify nonlinear associations and saturation effects between inflammation indices and cataract risk. Finally, receiver operating characteristic (ROC) curves were plotted for factors significantly associated with the development of cataracts to identify the optimal diagnostic inflammation index. This study included 8887 participants without cataracts and 935 participants with cataracts. Multivariate logistic regression analyses after adjusting for covariates revealed that a high SII (OR = 1.000, 95% CI = 1.000-1.000; P = 0.017) and high NLR (OR = 1.065, 95% CI = 1.000-1.134; P = 0.048) were independent risk factors for cataracts. Subgroup analyses did not reveal interactions between the SII, NLR, or cataract and covariates. Smoothed curve fits of the relationships between the SII or NLR and cataracts did not show positive significant saturating effect values for any of the variables. The ROC curve revealed some diagnostic value for cataracts for both the SII (AUC = 0.549, P < 0.001) and the NLR (AUC = 0.603, P < 0.001), but both had weak diagnostic value. Our study suggests that the SII and NLR are independent risk factors for cataracts in U.S. adults, but no such associations was identified between the PLR and cataracts.

Vitamin D levels and risk of ocular disorders: insights from bidirectional and multivariable Mendelian randomization analysis

Purpose

This study aimed to assess the causal relationships between vitamin D levels and ocular disorders.

Methods

Independent genetic variables were obtained from genome-wide association studies (GWAS) and publicly available databases. The summary statistics for 25-hydroxyvitamin D (25(OH)D) were obtained from two large-scale GWAS studies, with sample sizes of 324,105 and 417,580 European individuals. The genetic variants of myopia, primary open angle glaucoma (POAG), anterior iridocyclitis, senile cataract, diabetic retinopathy (DR), retinal vein occlusion (RVO), wet age-related macular degeneration (WAMD) and optic neuritis were extracted from the latest release of FinnGen consortium, which contains genome data from Finnish participants. Subsequently, Mendelian randomization (MR) analyses were conducted to obtain effect estimates. Additionally, we performed multivariable MR analysis and mediation analysis to validate the results.

Results

In the discovery dataset, genetically predicted vitamin D concentration was found to be causally associated with an increased risk of WAMD, (odd ratio (OR) = 1.35, 95% confidence interval (CI) = 1.09-1.67, P IVW = 0.005). However, no causal effects of genetically predisposed vitamin D levels on the risk of most types of ocular disorders were observed. Reverse MR revealed no causal relationships between the ocular diseases and vitamin D concentrations. The MR analyses of the validation dataset yielded consistent results. Additionally, the causal effect of vitamin D levels on the risk of WAMD remained significant after adjusting for potential confounders in the multivariable MR analysis (OR = 1.86, 95% CI = 1.26-2.73, P IVW = 0.002).

Conclusion

Our MR analysis results provide robust evidence of a causal relationship between genetically predicted 25(OH)D levels and an increased risk of WAMD in European population. These findings offer important insights into the management and control of ocular disorders.

The use of linked administrative data in Australian randomised controlled trials: A scoping review

BACKGROUND/AIMS

The demand for simplified data collection within trials to increase efficiency and reduce costs has led to broader interest in repurposing routinely collected administrative data for use in clinical trials research. The aim of this scoping review is to describe how and why administrative data have been used in Australian randomised controlled trial conduct and analyses, specifically the advantages and limitations of their use as well as barriers and enablers to accessing administrative data for use alongside randomised controlled trials.

METHODS

Databases were searched to November 2022. Randomised controlled trials were included if they accessed one or more Australian administrative data sets, where some or all trial participants were enrolled in Australia, and where the article was published between January 2000 and November 2022. Titles and abstracts were independently screened by two reviewers, and the full texts of selected studies were assessed against the eligibility criteria by two independent reviewers. Data were extracted from included articles by two reviewers using a data extraction tool.

RESULTS

Forty-one articles from 36 randomised controlled trials were included. Trial characteristics, including the sample size, disease area, population, and intervention, were varied; however, randomised controlled trials most commonly linked to government reimbursed claims data sets, hospital admissions data sets and birth/death registries, and the most common reason for linkage was to ascertain disease outcomes or survival status, and to track health service use. The majority of randomised controlled trials were able to achieve linkage in over 90% of trial participants; however, consent and participant withdrawals were common limitations to participant linkage. Reported advantages were the reliability and accuracy of the data, the ease of long term follow-up, and the use of established data linkage units. Common reported limitations were locating participants who had moved outside the jurisdictional area, missing data where consent was not provided, and unavailability of certain healthcare data.

CONCLUSIONS

As linked administrative data are not intended for research purposes, detailed knowledge of the data sets is required by researchers, and the time delay in receiving the data is viewed as a barrier to its use. The lack of access to primary care data sets is viewed as a barrier to administrative data use; however, work to expand the number of healthcare data sets that can be linked has made it easier for researchers to access and use these data, which may have implications on how randomised controlled trials will be run in future.

The Role of Vitamin D3 in Ocular Diseases

Vitamin D3 plays a vital role in numerous physiological processes within the human body, including having a positive effect on eye health. It is renowned for its immunomodulatory, anti-inflammatory, antioxidant, and angiogenic properties. Its deficiency is evolving into a significant global challenge. In order to explain the connection between vitamin D3 and various ocular diseases, 84 relevant studies, mainly from the PubMed database, published in English between 1999 and 2024 were analyzed. Ocular tissues can activate and regulate vitamin D levels, which emphasizes the significance of this nutrient in maintaining eye homeostasis. While there is suggestive evidence for a probable association between vitamin D3 and ocular health, more robust research is needed to establish causation and inform clinical guidelines.

Causal association between 25-hydroxyvitamin D status and cataract development: A two-sample Mendelian randomization study

BACKGROUND

Vitamin deficiencies are linked to various eye diseases, and the influence of vitamin D on cataract formation has been noted in prior research. However, detailed investigations into the causal relationship between 25-(OH)D status and cataract development remain scarce.

AIM

To explore a possible causal link between cataracts and vitamin D.

METHODS

In this study, we explored the causal link between 25-(OH)D levels and cataract development using Mendelian randomization. Our analytical approach included inverse-variance weighting (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods. The primary analyses utilized IVW with random effects, supplemented by sensitivity and heterogeneity tests using both IVW and MR-Egger. MR-Egger was also applied for pleiotropy testing. Additionally, a leave-one-out analysis helped identify potentially impactful single-nucleotide polymorphisms.

RESULTS

The analysis revealed a positive association between 25-(OH)D levels and the risk of developing cataracts (OR = 1.11, 95%CI: 1.00-1.22; P = 0.032). The heterogeneity test revealed that our IVW analysis exhibited minimal heterogeneity (P > 0.05), and the pleiotropy test findings confirmed the absence of pleiotropy within our IVW analysis (P > 0.05). Furthermore, a search of the human genotype-phenotype association database failed to identify any potentially relevant risk-factor single nucleotide polymorphisms.

CONCLUSION

There is a potential causal link between 25-(OH)D levels and the development of cataracts, suggesting that greater 25-(OH)D levels may be a contributing risk factor for cataract formation. Further experimental research is required to confirm these findings.

Vitamin D and human health: evidence from Mendelian randomization studies

We summarized the current evidence on vitamin D and major health outcomes from Mendelian randomization (MR) studies. PubMed and Embase were searched for original MR studies on vitamin D in relation to any health outcome from inception to September 1, 2022. Nonlinear MR findings were excluded due to concerns about the validity of the statistical methods used. A meta-analysis was preformed to synthesize study-specific estimates after excluding overlapping samples, where applicable. The methodological quality of the included studies was evaluated according to the STROBE-MR checklist. A total of 133 MR publications were eligible for inclusion in the analyses. The causal association between vitamin D status and 275 individual outcomes was examined. Linear MR analyses showed genetically high 25-hydroxyvitamin D (25(OH)D) concentrations were associated with reduced risk of multiple sclerosis incidence and relapse, non-infectious uveitis and scleritis, psoriasis, femur fracture, leg fracture, amyotrophic lateral sclerosis, anorexia nervosa, delirium, heart failure, ovarian cancer, non-alcoholic fatty liver disease, dyslipidemia, and bacterial pneumonia, but increased risk of Behçet's disease, Graves' disease, kidney stone disease, fracture of radium/ulna, basal cell carcinoma, and overall cataracts. Stratified analyses showed that the inverse association between genetically predisposed 25(OH)D concentrations and multiple sclerosis risk was significant and consistent regardless of the genetic instruments GIs selected. However, the associations with most of the other outcomes were only pronounced when using genetic variants not limited to those in the vitamin D pathway as GIs. The methodological quality of the included MR studies was substantially heterogeneous. Current evidence from linear MR studies strongly supports a causal role of vitamin D in the development of multiple sclerosis. Suggestive support for a number of other health conditions could help prioritize conditions where vitamin D may be beneficial or harmful.

Oxidative stress in the eye and its role in the pathophysiology of ocular diseases

Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.