Causal Associations Between Mobile Phone Usage and Glaucoma Risk: A Mendelian Randomization Study

Authors: Rui Song, Yinnuo Wang, Yanbo Kong, Xinyu Fan, Chuang Yuan, Xu Zha

Objective: The study aimed to explore the causal relationship between mobile phone usage and the risk of developing glaucoma using a Mendelian randomization (MR) approach to overcome issues of confounding and reverse causality in traditional observational studies.

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Methodology:

Study Design: Utilized a 2-sample MR framework where single nucleotide polymorphisms (SNPs) served as instrumental variables (IVs) for mobile phone usage duration and glaucoma incidence.
Data Sources: Data on mobile phone use were from the UK Biobank, while glaucoma data came from the FinnGen Project, both involving large sample sizes.
Instrumental Variable Selection: SNPs were selected based on genome-wide significance and were rigorously vetted for confounding and pleiotropy effects. The F-statistic was used to confirm the strength of IVs.

Key Findings:

Causal Relationship: The study established a significant causal link between the duration of mobile phone use and an increased risk of glaucoma, with odds ratios (ORs) from different MR methods consistently showing elevated risk (e.g., OR from IVW was 1.358 with a 95% CI of 1.052-1.752).
Sensitivity Analysis: Confirmed the robustness of the findings through tests for heterogeneity and pleiotropy, showing no significant issues that would undermine the results.

Mechanisms:

Blue Light Exposure: The blue light from mobile phone screens could damage mitochondria in retinal cells, contributing to glaucoma.
Intraocular Pressure (IOP): Prolonged use of mobile phones was linked to an increase in IOP, a known risk factor for glaucoma.
Myopia and Dark Environments: Mobile phone usage might increase myopia, which is a risk factor for glaucoma, especially when used in low light conditions.

Limitations:

Population Specificity: The study was conducted on individuals of European descent, potentially limiting generalizability.
Subtype Analysis: The research did not differentiate between glaucoma subtypes, which could affect the precision of the findings.

Conclusion: This study provides evidence that prolonged mobile phone use could be a modifiable risk factor for glaucoma, suggesting the need for further research into preventive strategies and mechanisms linking mobile phones to eye health.