Mendelian Randomization Implicates Bidirectional Association between Myopia and Primary Open-Angle Glaucoma or Intraocular Pressure

An Ocular Exposure Prediction for Topical Atropine in Human Using Physiologically Based Pharmacokinetic Modeling

Developing a mathematical model to predict the distribution and bioavailability of atropine in human eyes is an insight approach for clinical practice. This study aims to develop a human ocular physiologically based pharmacokinetic (PBPK) modeling for the ophthalmic drug atropine and explore possible mechanisms by which atropine reduces myopia progression in children. The Ocular Compartment Absorption and Transit (OCAT™) model was employed to describe the ocular distribution of atropine following administration at different dosages in both rabbits and humans. The PBPK model enables the extrapolation of pharmacokinetic characteristics among different species depending on theirphysiology and anatomy. The developed and validated OCAT-PBPK model demonstrated good agreement with observed data from rabbit ocular tissues and human aqueous humor. Fifty-eight percent of simulations fell within the standard deviation range of experimental data. The extrapolated human PBPK model for accurately predicted the ocular exposure and distribution following the administration of low-concentration atropine. This study confirms the performance of the ocular PBPK model in predicting ocular pharmacokinetic behavior among different species. Model's predictions indicate that atropine shows significant potential to penetrate the posterior eye segment, providing underlying insights into its mechanisms of action in the eye.

Sectoral Changes in Neuroretinal Rim Pallor Across Refractive Error

Purpose

To investigate the association between spherical equivalent refraction (SER) and pallor in different neuroretinal rim (NRR) sectors.

Design

Population-based cross-sectional study.

Participants

Normal eyes of 24 057 healthy participants aged 40 to 70 years from the UK Biobank.

Methods

Pallor in different NRR sectors was quantitatively derived from color fundus photographs using automated software. We first examined the association between SER and pallor in each NRR sector-controlling for age, sex, ethnicity (White vs. non-White), intraocular pressure, and mean blood pressure. We then incorporated disc-fovea distance (the shortest distance from the center of the disc to the fovea) and temporal arterial/venous concavity (extent to which the temporal artery/vein curved inwardly toward the fovea) as additional independent variables, as these features have been suggested to reflect the degree of axonal stretching at the posterior pole.

Main Outcome Measures

Pallor in the temporal, temporal inferior, nasal inferior, nasal, nasal superior, and temporal superior sectors of the NRR.

Results

Moving from the temporal sector to the temporal superior sector, NRR pallor varied in an asymmetrical U-shaped pattern, with the least pallor observed nasally. White participants tended to have paler NRR, but the association between SER and pallor did not differ between ethnic groups (no interaction effect between SER and ethnicity). Decreasing SER was associated with increasing pallor in all 6 NRR sectors (all P < 0.001), but the temporal (ß: -0.009, 95% confidence interval: -0.011 to -0.008) and temporal inferior (ß: -0.008, 95% confidence interval: -0.009 to -0.007) sectors exhibited the steepest increase. The rate of increase diminished by half toward the more nasal/central sectors, and by another half in the nasal-most sector. Consistent with these changes, increasing disc-fovea distance and temporal arterial/venous concavity resulted in up to 4 times as much pallor temporally compared with nasally. These retinal changes accounted for approximately ≥50% of the effect of SER on NRR pallor.

Conclusions

Decreasing SER increases NRR pallor approximately 4 times faster temporally than nasally. The association between SER and NRR pallor is primarily attributable to changes in disc-fovea distance and temporal arterial/venous concavity. These findings suggest that the papillomacular nerve fiber bundle, linked to the temporal NRR, is most susceptible to myopic stretching.

Financial Disclosures

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

Association Between Inflammatory Cytokines and Refractive Errors: A Bidirectional Mendelian Randomization Study

Purpose

This investigation aimed to elucidate the causal role of inflammatory cytokines in the risk of developing refractive errors.

Methods

Genetic variants previously associated with inflammatory cytokines served as instrumental variables in genome-wide association studies (GWASs) of European ancestry. Bidirectional two-sample Mendelian randomization (MR) analyses were conducted using summary data from GWAS meta-analyses. Rigorous sensitivity analyses were performed to validate the reliability of the MR results.

Results

We found that, for every unit increase in interleukin 1 receptor antagonist (IL1RA) and interleukin 2 (IL2), there was a corresponding decrease in the prevalence of myopic refractive errors by 0.235 (95% confidence interval [CI], 0.050-0.419 for fixed effects; 95% CI, 0.125-0.345 for random effects) and 0.132 (95% CI, 0.032-0.231 for fixed effects; 95% CI, 0.044-0.220 for random effects), respectively. No substantial causal associations were observed for IL1α, IL1β, IL12p70, or monocyte chemoattractant protein 1 (MCP1) with refractive errors. Conversely, reverse MR analyses failed to indicate a causal influence of refractive errors on IL1RA and IL2.

Conclusions

The present study offers evidence for a causal link between inflammatory cytokines and refractive errors, which could have significant implications for the early detection, surveillance, and management of refractive errors.

Translational Relevance

Our study underscores the importance of IL1RA and IL2 in the prevention and management of refractive errors, suggesting the feasibility of strategies for early identification, continuous surveillance, and the deployment of focused therapeutic approaches.

Longitudinal corneal hysteresis changes predict structural progression in medically controlled, early-to-moderate, open-angle glaucoma with a history of refractive surgery

BACKGROUND

The present study aims to identify the relationship between longitudinal changes in corneal hysteresis (CH) and progressive retinal nerve fibre layer (RNFL) thinning in a cohort of medically controlled, early-to-moderate open-angle glaucoma (OAG) patients with a history of laser refractive surgery (LRS).

METHODS

A total of 123 consecutive eyes with a diagnosis of medically controlled (peak intraocular pressure (IOP)<18 mm Hg), early-to-moderate OAG with a history of LRS underwent measurements of CH, corneal-compensated intraocular pressure (IOPcc) and RNFL thicknesses every 6 months. Linear models were used to investigate the relationship between CH change and RNFL thickness change over time.

RESULTS

Of 123 eyes, 30 eyes (24.4%, 42.9±9.3 years, 36.7% males) demonstrated RNFL loss (93 eyes no progression, 44.4±9.6 years, 30.1% males). No statistically significant difference was found in IOP, but significantly greater decrease in CH was noted in the progression group (-2.525% baseline (95% CI -4.974 to -0.076) vs 1.068% baseline (95% CI, -0.322 to 2.458); p=0.013). Relative CH change was greater for more advanced stage of OAG among the progression group. Patients with the greatest relative CH decrease over time was 1.7 times more likely to present RNFL loss (HR 1.705, 95% CI 1.113 to 2.611, p=0.014).

CONCLUSIONS

Longitudinal decrease in CH over time was greater in those showing structural progression than those without progression among medically controlled, early-to-moderate OAG with a history of LRS. Decrease in CH was significantly associated with faster RNFL loss. Larger CH changes indicate a higher risk of OAG progression in those with a history of LRS.

Causal Links Between Corneal Biomechanics and Myopia: Evidence from Bidirectional Mendelian Randomization in the UK Biobank

BACKGROUND

Myopia is a leading cause of visual impairment worldwide, and accumulating evidence suggests that biomechanics may be closely linked to its development. Understanding this relationship may help clarify the underlying mechanisms of myopia and guide treatment strategies. The aim of the study is to investigate the causal relationship between myopia and corneal biomechanics using the UK Biobank (UKB) database.

METHODS

Data from 11,064 eyes in the UKB, including refraction results and Ocular Response Analyzer (ORA) measurements, were analyzed. Eyes were categorized by spherical equivalent (SE) into emmetropia, mild myopia, moderate myopia, and high myopia. One-way ANOVA assessed differences in corneal biomechanical parameters across the varying myopia groups, while Quantile Regression (QR) explored the relationship between these parameters and myopia severity across the different quantiles. A Mendelian randomization (MR) analysis was employed to explore the causal relationships.

RESULTS

Significant differences in corneal biomechanical parameters and intraocular pressure (IOP) were observed across the myopia levels (p < 0.001). High myopia was associated with lower corneal hysteresis (CH), a lower corneal resistance factor (CRF), and increased IOP. The QR analysis demonstrated that lower corneal biomechanics were associated with higher degrees of myopia, with the impact of corneal biomechanics becoming more pronounced as the myopia severity increased. The MR analysis indicated that low CH (OR = 0.9943, p = 0.004) and CRF (OR = 0.9946, p = 0.002) values were risk factors for myopia, while no causal effect was found when the myopia was treated as the exposure and corneal biomechanics as the outcome.

CONCLUSIONS

This study establishes a causal relationship where reduced corneal biomechanics contribute to myopia, while myopia itself does not directly affect biomechanics. Corneal biomechanics could serve as a biomarker for assessing high myopia risk. These findings offer new insights into high myopia's pathological mechanisms and targeted prevention.

Association of physical activity, sedentary behaviour, sleep and myopia in children and adolescents: a systematic review and dose-response meta-analysis

PURPOSE

This study aimed to systematically evaluate the dose-response relationships between physical activity (PA), sedentary behavior(SB) (including near work [NW] and screen time [ST]), sleep duration (SD), and myopia risk among children and adolescents.

DESIGN

Systematic review and dose-response meta-analysis.

METHODS

We systematically searched PubMed, EMBASE, Cochrane Library, and Web of Science up to November 19, 2024. Methodological quality was assessed using Joanna Briggs Institute (JBI) and ROBINS-I tools. Random-effects meta-analyses were used to estimate categorical and continuous dose-response relationships. Subgroup analyses and sensitivity analyses were performed to explore heterogeneity sources and test robustness.

RESULTS

A total of 45 observational studies (766,848 participants aged 5-19 years) were included. Categorical analyses showed that, compared with the lowest exposure categories, higher PA levels (highest: OR = 0.77, 95% CI: 0.63-0.96; intermediate: OR = 0.76, 95% CI: 0.63-0.93) and longer SD (highest: OR = 0.67, 95% CI: 0.48-0.92; intermediate: OR = 0.82, 95% CI: 0.73-0.92) significantly reduced myopia risk. Conversely, higher levels of NW (highest: OR = 1.71, 95% CI: 1.28-2.27; intermediate: OR = 1.34, 95% CI: 1.19-1.50) and ST (highest: OR = 1.59, 95% CI: 1.14-2.22; intermediate: OR = 1.29, 95% CI: 1.12-1.49) were associated with significantly increased risk. In the continuous dose-response meta-analysis, a linear association was observed between PA, ST, and myopia. Each additional hour of PA per day reduced the risk of myopia by 12%, while each additional hour of ST increased the risk by 31%. Nonlinear associations were found between NW, SD, and myopia. Among children and adolescents, 1.5 and 2.5 h/day of NW increased the risk of myopia by 25% and 29%, respectively. Although longer SD was associated with a reduced risk of myopia, this effect did not reach statistical significance at any exposure level.Subgroup analyses revealed that protective effects of PA were more evident in low- and middle-income countries, smaller sample sizes, and cross-sectional studies, while increased risks related to ST and NW were stronger in low-income settings. No subgroup significantly modified the association between SD and myopia risk.

CONCLUSION

Increasing PA, while limiting ST and NW, effectively reduces the risk of myopia among children and adolescents. The association between sleep duration and myopia remains inconclusive, warranting further investigation.

Genetic risk factors associated with ocular perfusion pressure in primary open-angle glaucoma

BACKGROUND

Primary open-angle glaucoma (POAG) is the leading cause of irreversible vision loss. However, its genetic risk factors, such as the vascular hypothesis of POAG, remain unclear. Here, we aimed to explore the genetic associations between mean ocular perfusion pressure (MOPP) and POAG. We performed genome-wide analysis with gene-based analysis from the UK Biobank (N = 459,195), which includes genetic data and ocular phenotypes. Bidirectional two-sample Mendelian randomisation (MR), multivariable MR, and mediation analysis were conducted using summary statistics from a previous meta-analysis of genome-wide association studies (N = 216,257).

RESULTS

CEP85L, GRIA4, GRIN2A, LRFN5, MAGI1, POU6F2, RBFOX1, RBMS1, RBMS3, RBPMS, TRHDE, TUBB3, ZFHX3, and ZMAT4 were significantly correlated with various ocular phenotypes. Furthermore, POAG shared strong genetic associations with corneal resistance factor (CRF), intraocular pressure (IOP), refractive error (RE), and MOPP but none with corneal hysteresis (CH). Univariable MR showed a negative causal effect of CH, CRF, and MOPP and a positive causal effect of IOP on POAG occurrence. In multivariable MR, MOPP exhibited a direct causal effect on POAG, which was supported by the mediation analysis results.

CONCLUSIONS

We successfully determined 14 genetic loci related to CH, CRF, IOP, RE, and MOPP. In univariable and multivaribale MR analyses, a causal effect of MOPP on POAG were observed. In addition, the mediation analysis supported that MOPP exerted direct and indirect causal effects on POAG. This finding indicates that MOPP may serve as a potential causal factor in POAG, providing valuable insights into the pathophysiology of POAG as vascular theory.

Genome-wide association studies, Polygenic Risk Scores and Mendelian randomisation: an overview of common genetic epidemiology methods for ophthalmic clinicians

Genetic information will be increasingly integrated into clinical eye care within the current generation of ophthalmologists. For monogenic diseases such as retinoblastoma, genetic studies have been relatively straightforward as these conditions result from pathogenic variants in a single gene resulting in large physiological effects. However, most eye diseases result from the cumulative effects of multiple genetic variants and environmental factors. In such diseases, because each variant usually has an individually small effect, genetic studies for complex diseases are comparatively more challenging. This article aims to provide an overview of three genetic epidemiology methods for polygenic (or complex) diseases: genome-wide association studies (GWAS), Polygenic Risk Scores (PRS) and Mendelian randomisation (MR). A GWAS systematically conducts association analyses of a trait of interest against millions of genetic variants, usually in the form of single nucleotide polymorphisms, across the genome. GWAS findings can then be used for PRS construction and MR analyses. To construct a PRS, the cumulative effect of many genetic variants associated with a trait from a prior GWAS is calculated and taken as a quantitative representation of an individual's genetic risk of a complex disease. MR studies analyse an outcome measure against the genetic variants of an exposure, and are particularly useful in investigating causal relations between two traits where randomised controlled trials are not possible or ethical. In addition to explaining the principles of these three genetic epidemiology concepts, this article provides a minimally technical description of their basic methodology that is accessible to the non-expert reader.

Hyperopia may exert a protective effect against senile cataracts: Evidence from a Mendelian randomization study

Myopia has been extensively documented as a significant risk factor for cataracts; however, the relationship between hyperopia and cataract development remains poorly understood. Given the distinct refractive profiles of myopia and hyperopia, hyperopia may confer a protective effect against cataracts. In this study, we employed Mendelian randomization (MR) to examine the causal association between hyperopia and cataracts. A 2-sample MR framework was utilized to examine the causal relationship between hyperopia and cataracts, with multivariable MR implemented to account for potential confounding variables. The inverse variance weighted (IVW) method served as the primary analytical tool, complemented by multiple sensitivity analyses to ensure the robustness and reliability of the findings. Enrichment analyses were conducted to elucidate the underlying biological pathways, while Bayesian colocalization analysis pinpointed shared genetic loci that influence both hyperopia and cataracts. In our study, we found that hyperopia may exert a protective effect against cataracts (IVW odds ratio, 0.920 [95% confidence interval, 0.872-0.972]; P = .0029) and cataract surgery (IVW odds ratio, 0.811 [95% confidence interval, 0.754-0.873]; P < .0001). Multivariable MR, adjusting for confounding factors such as smoking, glaucoma, and diabetes, confirmed hyperopia's protective association with cataracts. Bayesian colocalization identified rs12193446 as a high-probability shared causal variant, while enrichment analyses revealed potential biological mechanisms linking hyperopia to cataract development. Genetic evidence suggests that higher levels of hyperopia are associated with a reduced risk of age-related nuclear cataracts, cataract extraction, and lens implants. Given the opposite refractive states of myopia and hyperopia and their opposite effects on cataracts, these findings provide new insights into the pathogenesis of age-related cataracts.

Exploring the neural mechanisms linking healthy aging and cognitive maintenance: insights from Mendelian randomization and mediation analyses

As global population ages, maintaining cognitive health in elderly is crucial. Previous studies suggest a positive link between healthy aging and cognition, but the neural mechanisms remain unclear. This study used genome-wide association studydata to investigate neural mechanisms between healthy aging and cognition. We employed 2-sample Mendelian randomization to evaluate causal relationship between healthy aging (indexed by a multivariate genetic predictor, mvAge) and 6 cognitive measurements. We then used a 2-step Mendelian randomization approach and mediation analysis to identify brain imaging-derived phenotypes potentially mediating this relationship. Mendelian randomization analysis indicated that healthy aging had a positive causal relationship with various cognitive functions (common executive function, intelligence, cognitive performance, and fluid intelligence score). Two-step Mendelian randomization analysis identified 27 brain imaging-derived phenotypes having robust causal relationships with healthy aging and various cognitive measurements. Mediation analysis suggested that volume of subcallosal cortex might mediate effects of healthy aging on all 4 cognitive functions. Volume of cerebellum's VIIb could mediate effects on common executive functions, while fractional anisotropy in the anterior thalamic radiation might mediate effects on intelligence and cognitive performance. These findings suggest that specific brain regions may play a potential mediating role in the relationship between healthy aging and cognitive maintenance.

Association between myopia and diabetic retinopathy: A two-sample mendelian randomization study

Objective

The association between myopia and diabetic retinopathy (DR) is unclear, with inconsistent results reported, and whether the association represents causality remains unknown. This study aimed to investigate the causal associations of genetically determined myopia with DR, and further explore specific mechanisms.

Methods

We conducted two-sample mendelian randomization (MR) analyses of any myopia and high myopia on six DR phenotypes, including any DR, background DR, severe background DR, proliferative DR (PDR), diabetic maculopathy and unspecific DR in the primary study. Mechanism exploration of spherical equivalent refraction (SER), corneal curvature (CC) and axial length (AL) on any DR was carried out subsequently. Single-nucleotide polymorphisms (SNPs), used as genetic instruments, were derived from UK Biobank, Genetic Epidemiology Research on Adult Health and Aging cohort (GERA) and FinnGen. The inverse variance weighted (IVW) method was mainly used to assess the causality, and was complemented with sensitivity analyses and causality direction analyses.

Results

Using SNPs that have excluded possible confounders, we discovered suggestive and positive causal associations of any myopia with any DR (IVW: odds ratio [OR] ​= ​1.133, 95% confidence interval [95%CI]: 1.070-1.201, P ​= ​1.91×10-5) and PDR (IVW: OR ​= ​1.182, 95% CI: 1.088-1.285, P ​= ​8.31×10-5). Similar but more significant associations were found of high myopia with any DR and PDR (IVW: OR ​= ​1.107, 95%CI: 1.051-1.166, P ​= ​1.39×10-4; OR ​= ​1.163, 95%CI: 1.088-1.244, P ​= ​8.76×10-6, respectively). Further mechanism analyses found only AL, rather than SER or CC, was strongly and significantly associated with any DR. These associations were robust in sensitivity analyses and causality direction analyses.

Conclusions

We found significant and positive causal associations of any myopia and high myopia with the risk of DR and PDR, which might be related with AL, indicating the significance of myopia control for preventing DR development and progression.

The whole life cycle myopia management

Myopia stands as a prevalent ocular condition with global implications, impacting individuals at various life stages. In school-age children and adolescents, uncorrected myopia impedes reading and academic performance. Among middle-aged and elderly populations, myopia poses severe risks such as macular degeneration, macular holes and retinal detachment, leading to irreversible visual impairment. The term "myopia management" is widely embraced by ophthalmic practitioners and optometry associations worldwide, encompassing strategies to correct refractive errors and ongoing assessment of disease progression, aiming to reduce the progression of myopia and axial elongation. To date, current management strategies for myopia include public health policies, optical solutions, medical interventions and surgical options, but these interventions are general and lack age specificity. Despite existing interventions, we propose the concept of "Whole Life Cycle Myopia Management" in this review. This approach outlined major risk factors of myopia through the whole life cycle, discussed current interventions for myopia and provided age-specific management strategies for myopia of eight different life stages-infancies, toddlers, preschoolers, school-age children, adolescents, young adults, middle-age and old-age, including the prevention of myopia onset, slowing of myopia progression and monitoring of myopia complications. Achieving the "Whole Life Cycle Myopia Management" requires collaborations efforts from government, schools, hospitals and families, to restore vision and enhance the quality of life for those individuals affected by myopia.

Lipid Profiles, Telomere Length, and the Risk of Malignant Tumors: A Mendelian Randomization and Mediation Analysis

Background/Objectives: The relationship between lipid profiles, telomere length (TL), and cancer risk remains unclear. Methods: This study employed two-sample Mendelian randomization (MR) with mediation analysis to investigate their causal relationships, examining lipid profiles as exposure, TL as mediator, and nine cancer types as outcomes. We conducted our analysis using two-stage least squares (2SLS) regression integrated with inverse variance weighted (IVW) methods to address potential endogeneity and strengthen our causal inference. Results: we found that unfavorable lipid profiles were causally linked to increased TL (p < 0.05). TL showed positive causal associations with lung and hematologic cancers (OR > 1, p < 0.05). Direct associations were observed between total and low-density lipoprotein (LDL) cholesterol and gastric cancer (OR < 1, p < 0.05), and between remnant cholesterol and colorectal cancer (OR > 1, p < 0.05). Mediation analysis revealed TL as a significant mediator in the pathway from lipid profiles to cancer development (p < 0.05). No horizontal pleiotropy was detected. Conclusions: Our findings suggest that lipid metabolism disorders may influence cancer development through telomere regulation, particularly in lung and hematologic cancers. This emphasizes the importance of lipid management in cancer prevention and treatment, especially for these cancer types.

Potential Causal Association Between Atrial Fibrillation/Flutter and Primary Open-Angle Glaucoma: A Two-Sample Mendelian Randomisation Study

Background: A few studies have reported controversial relationships between atrial fibrillation/flutter (AF/L) and primary open-angle glaucoma (POAG). This study aimed to investigate the potential causal relationship between AF/L and POAG. Methods: Single-nucleotide polymorphisms associated with exposure to AF/L were selected as instrumental variables with significance (p < 5.0 × 10-8) from a genome-wide association study (GWAS) by FinnGen. The GWAS summary of POAG from the UK Biobank was used as the outcome dataset. A two-sample Mendelian randomisation (MR) study was performed to assess the causal effects of AF/L on POAG. In addition, potential confounders, including hypertension, autoimmune hyperthyroidism, sleep apnoea, and alcohol use disorder, were assessed using multivariable MR analysis. Results: There was a significant causal association of AF/L with POAG (odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.07-1.48, p = 0.005 using inverse-variance weighting [IVW]). Multivariable MR analysis confirmed a causal association of AF/L with POAG (OR = 1.24, 95% CI = 1.02-1.51, p = 0.034 using IVW), but hypertension, hyperthyroidism, sleep apnoea and alcohol use disorder did not show significant causal associations with POAG (all p > 0.05). Conclusions: This established causal relationship between AF/L and POAG supports the need for further investigation into the role of AF/L as a possible risk factor for POAG. Further research is required to confirm these findings.

A multi-omics Mendelian randomization identifies putatively causal genes and DNA methylation sites for asthma

Background

Asthma is a global chronic respiratory disease with complex pathogenesis. While current therapies offer some relief, they often fall short in effectively managing symptoms and preventing exacerbations for numerous patients. Thus, understanding its mechanisms and discovering new drug targets remains a pressing need for better treatment.

Methods

Using the GEO dataset, we screened differentially expressed genes (DEGs) in asthma patients' blood. Employing Summary Data-based Mendelian Randomization (SMR) and Two-Sample Mendelian Randomization (TSMR), we pinpointed asthma causal genes, causal DNA methylation sites, and methylation sites affecting gene expression, cross validated with at least 2 large-scale GWAS from each source. We utilized colocalization for genetic associations, meta-analysis for data integration, two-step MR for methylation-gene-asthma mediation mechanism. Druggability was evaluated using Open Target, virtual screening, and docking.

Results

Among the 954 DEGs found in asthma patients' blood, increased expression of CEP95 (discovery, OR_SMR = 0.94, 95% CI: 0.91-0.97), RBM6 (discovery, OR_SMR = 0.97, 95% CI: 0.95-0.99), and ITPKB (discovery, OR_SMR = 0.82, 95% CI: 0.74-0.92) in the blood decreased the risk of asthma, higher levels of HOXB-AS1 (discovery, OR_SMR = 1.05, 95% CI: 1.03-1.07), ETS1 (discovery, OR_SMR = 1.62, 95% CI: 1.29-2.04), and JAK2 (discovery, OR_SMR = 1.13, 95% CI: 1.06-1.21) in the blood increased the risk of asthma. Additionally, a total of 8 methylation sites on ITPKB, ETS1, and JAK2 were identified to influence asthma. An increase in methylation at site cg16265553 raised the risk of asthma partially by suppressing ITPKB expression. Similarly, increased methylation at cg13661497 reduced the asthma risk totally by suppressing JAK2 expression. The impact of CEP95, HOXB-AS1, and RBM6 expressions on asthma was further confirmed in lung tissues. Except for HOXB-AS1, all the other genes were potential druggable targets.

Conclusion

Our study highlighted that specific gene expressions and methylation sites significantly influence asthma risk and revealed a potential methylation-to-gene-to-asthma mechanism. This provided pivotal evidence for future targeted functional studies and the development of preventive and treatment strategies.

Omega-3 Polyunsaturated Fatty Acids as a Protective Factor for Myopia

PURPOSE

Animal models suggest omega-3 polyunsaturated fatty acids (PUFAs) may protect against myopia by modulating choroidal blood perfusion, but clinical evidence is scarce and mixed. We aimed to determine the causality between omega-3 PUFAs and myopia using Mendelian randomization (MR) analysis.

DESIGN

Two-sample MR analysis.

METHODS

Exposures are genetically predicted plasma levels of 18 fatty acid (FA)-related traits. Spherical equivalent refraction (SER) and axial length were used as measurements of myopia. Genome-wide association study summary data on plasma levels of 18 FA-related traits (n=115,006), refractive spherical equivalent (n=351,091), axial length (n=69,945), and choroidal thickness (n=44,823) were sourced from the UK Biobank, the Genetic Epidemiology Research on Adult Health and Aging cohort, and the Consortium for Refractive Error and Myopia Study. We used 5 MR models and considered results statistically significant if the Bonferroni-corrected P value was ≤2.78 ×10-3 in at least 3 MR models. The β represents the change in outcomes (SER in diopters; axial length in millimeters; and choroidal thickness in SD) per SD unit increase in FA levels.

RESULTS

At a Bonferroni-corrected significance, higher levels of omega-3 (β, 0.32-0.34), omega-3-total FA ratio (β, 0.31-0.44), docosahexaenoic acid (DHA) (β, 0.36-0.46), DHA-total FA ratio (β, 0.37-0.53), PUFA-total FA ratio (β, 0.07-1.003), and degree of unsaturation (β, 0.28-0.44) were associated with a more positive SER, suggesting a lower risk of myopia. Similar trends were observed for axial length albeit with borderline significance (P ≤ .035 in ≥2 models). Higher levels of omega-3, DHA, DHA-total FA ratio, PUFA-total FA ratio, PUFA-monounsaturated FA ratio, and degree of unsaturation were nominally associated with thicker choroidal thickness (β, 0.05-0.13; P ≤ .045 in ≥2 models).

CONCLUSION

Our multiple MR models suggest a protective effect of omega-3 and DHA on myopia, potentially through modulation of choroidal blood perfusion. Further randomized clinical trials are needed to confirm the effectiveness and determine the optimal dose and duration.

Axial elongation in nonpathologic high myopia: Ocular structural changes and glaucoma diagnostic challenges

Axial elongation continues in highly myopic adult eyes, even in the absence of pathologic changes such as posterior staphyloma or chorioretinal atrophy. This ongoing axial elongation leads to structural changes in the macular and peripapillary regions, including chorioretinal thinning, reduced vascular perfusion and optic disc tilting and rotation, among others. These alterations can affect the acquisition and interpretation of optical coherence tomography, optical coherence tomography angiography and fundus photographs, potentially introducing artifacts and diminishing the accuracy of glaucoma diagnosis in highly myopic eyes. In this review, we compared the progression patterns of axial elongation across populations with varying demographic characteristics, genetic and environmental backgrounds and ocular features. We also discussed the implications of axial elongation-induced ocular structural changes for diagnosing glaucoma in nonpathologic high myopia. Finally, we highlighted the prospects for enhancing the diagnostic efficacy of glaucoma in nonpathologic highly myopic populations.

The lack of causal link between myopia and intraocular pressure: Insights from cross-sectional analysis and Mendelian randomization study

OBJECTIVE

This study aimed to explore the potential causal relationship between intraocular pressure (IOP) and myopia.

METHODS

The study included 3,459 patients who underwent corneal refractive surgery at our institution between 2021 and 2023. Preoperative data on IOP, spherical equivalent (SE), axial length (AL), and corneal thickness (CCT) were collected. The association between IOP and myopia was investigated through rank correlation analysis, and causal inference was examined using Mendelian randomization (MR) methods, including MR-Egger, weighted median, mode-based estimation, simple mode, and inverse variance weighted (IVW) approaches. Utilizing summary statistics from genome-wide association studies (GWAS), IOP was considered as the exposure, with myopia as the outcome variable. IVW method was employed for the primary analysis, supplemented by sensitivity analyses.

RESULTS

Cross-sectional analysis revealed a non-significant association between corrected IOP (cIOP) and myopia (r = -0.019, P = 0.12). MR analysis indicated a non-significant genetic causal relationship between cIOP and myopia under the IVW method (OR = 1.001; 95 % CI [0.999-1.003], P = 0.22), a finding corroborated in replication samples (OR = 0.98; 95 % CI [0.96-1.00], P = 0.099).

CONCLUSION

This study did not find a direct causal link between IOP and the development of myopia. These findings challenge the traditional role attributed to IOP in the progression of myopia and highlight the complex, multifactorial process of myopia development. This provides a new perspective on understanding the intricate mechanisms behind myopia progression.

Genetic insights into the association between serum cytokines and frozen shoulder risk: A bidirectional mendelian randomization study

BACKGROUND

Although existing studies have indicated a connection between chronic low-grade inflammation and the onset of frozen shoulder (FS), the precise causal relationship between distinct circulating inflammatory factors and FS has yet to be thoroughly evaluated. In this study, we employed a bidirectional two-sample Mendelian randomization (MR) analysis to investigate the potential causal relationship between systemic cytokines and FS.

METHODS

A genome-wide association dataset comprising 41 serum cytokines from 8,293 individuals of Finnish descent was utilized, along with FS data from the UK Biobank included 10,104 FS cases and 451,099 controls. The primary MR method was the inverse variance weighted approach, and four additional MR techniques (MR-Egger, weighted median, simple mode, and weighted mode) were also employed to support and validate the findings. Heterogeneity and horizontal pleiotropy assessments were assessed using Cochrane's Q and MR-Egger intercept tests. Moreover, a series of sensitivity analyses were conducted to strengthen the accuracy and credibility of these findings.

RESULTS

Based on the IVW method, genetically predicted increasing levels of growth regulated oncogene alpha (GROa) (OR=1.08, 95 % CI 1.02-1.13, P=0.005), interferon gamma-induced protein 10 (IP-10) (OR=1.09, 95 % CI 1.02-1.17, P=0.010), regulated on activation, C-C Motif Chemokine Ligand 5 (CCL5) (OR=1.11, 95 % CI 1.03-1.20, P=0.007) were suggestively associated with an increased risk of FS. Reverse MR analysis revealed no significant causal effect of FS on the 41 systemic inflammatory factors. No heterogeneity or horizontal pleiotropy was observed in our analysis.

CONCLUSION

This study established a causal association between 41 systemic inflammatory factors and FS, indicating that elevated levels of GROa, IP-10 and CCL5 were associated with a higher risk of FS. Further research is warranted to explore the potential of these biomarkers as early predictors and therapeutic targets for FS.

Complications of high myopia: An update from clinical manifestations to underlying mechanisms

Background

High myopia is one of the major causes of visual impairment and has an ever-increasing prevalence, especially in East Asia. It is characterized by excessive axial elongation, leading to various blinding complications that extend beyond mere refractive errors and persist immovably after refractive surgery, presenting substantial public health challenge.

Main text

High myopia-related complications include lens pathologies, atrophic and tractional maculopathy, choroidal neovascularization, peripheral retinal degenerations and retinal detachment, and glaucoma and heightened susceptibility to intraocular pressure (IOP) elevation. Pathological lens changes characteristic of high myopia include early cataractogenesis, overgrowth of lens, weakened zonules, and postoperative capsular contraction syndrome, possibly driven by inflammatory pathogenesis, etc. Dome-shaped macula and cilioretinal arteries are two newly identified protective factors for central vision of highly myopic patients. These patients also face risks of open-angle glaucoma and IOP spike following intraocular surgery. Morphologic alternations of optic nerve in high myopia can complicate early glaucoma detection, necessitating comprehensive examinations and close follow-up. Anatomically, thinner trabecular meshwork increases this risk; conversely lamina cribrosa defects may offer a fluid outlet, potentially mitigating the pressure. Notably, anxiety has emerged as the first recognized extra-ocular complication in high myopia, with an underlying inflammatory pathogenesis that connects visual stimulus, blood and brain.

Conclusions

High myopia induces multiple ocular and potential mental health complications, underscoring the need to develop more effective strategies to improve both physical and emotional well-being of these patients, among which anti-inflammation might possibly represent a promising new target.

Prevalence and associated factors of myopia among adolescents aged 12-15 in Shandong Province, China: a cross-sectional study

Myopia is a growing concern worldwide, especially among adolescents. This study aimed to investigate the prevalence and associated factors of myopia in adolescents aged 12-15 in Shandong Province, China. This cross-sectional study adhered to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines and involved stratified random cluster sampling of 128,678 students from 186 middle schools across 17 cities in Shandong Province. Data collection was conducted from March to April 2024. We excluded students with organic eye diseases, abnormal binocular vision functions, or a history of eye injuries or surgeries. Myopia was assessed using the standard logarithmic visual acuity chart and autorefractor without inducing ciliary muscle paralysis. A comprehensive questionnaire survey was conducted to gather demographic characteristics and daily life behaviors. With the chi-squared test for univariable analysis and multivariable logistic regression for identifying significant factors. This study included 126,375 participants, with a gender distribution of 51.02% male and 48.98% female. The overall prevalence of myopia was 71.34%. Higher prevalence was observed in girls (72.26%) compared to boys (70.45%), and the prevalence increased with age, peaking at 73.12% in 15-year-olds. Urban residents had a higher prevalence (71.86%) than rural (70.39%). Factors such as increased frequency of eye usage while lying down or leaning forward, frequent use of eyes while walking or riding in a car, prolonged screen time, and extended homework duration were associated with higher odds of developing myopia. Conversely, higher frequency of outdoor exercise, maintaining proper posture during reading and writing, greater distance from eyes to screen, and longer sleep duration were associated with lower odds. Additionally, female gender, older age, urban residence, and parental history of myopia increased the risk. The high prevalence of myopia among adolescents in Shandong Province was influenced by a combination of demographic, behavioral, and environmental factors. The study highlighted the importance of lifestyle modifications, such as increasing outdoor activities and maintaining proper visual habits, limiting the duration of screen exposure and homework sessions, and extending sleep duration, to mitigate the risk of developing myopia. These findings underscored the need for targeted public health interventions and educational campaigns to address this significant public health issue.

Genetic correlation and causal relationship between sleep and myopia: a mendelian randomization study

Purpose

To investigate the genetic correlation and causal links between sleep traits (including sleep duration, chronotype, and insomnia) and myopia.

Methods

Summary data on three sleep traits (sleep duration, chronotype and insomnia) and myopia from FinnGen (n = 214,211) and UK Biobank (n = 460,536) were analyzed using linkage disequilibrium score regression (LD Score), univariable and multivariable mendelian randomization (MR) experiments and Causal Analysis Using Summary Effect (CAUSE) estimation.

Results

LD Score regression detected candidate genetic correlation between sleep traits and myopia, such as sleep duration, chronotype (Genetic Correlation Z-score >10.00, h2_observed_p < 0.005, Lambda GC > 1.05, p > 0.05). Univariable MR analyses indicated that increased sleep duration has a promotional effect on the occurrence of myopia (p = 0.046 < 0.05, P_FDR = 0.138 < 0.2, OR = 2.872, 95% CI: 1.018-8.101). However, after accounting for potential confounding factors, multivariable MR and CAUSE analysis did not provide evidence for a causal effect of the three sleep traits on myopia.

Conclusion

There may be a potential genetic correlation between sleep duration, chronotype and myopia. However, neither of sleep duration, chronotype or insomnia had causal effect on myopia.

Low-grade systemic inflammation links heavy metal exposures to mortality: A multi-metal inflammatory index approach

Certain heavy metals have been correlated to an elevated risk of inflammation-related diseases and mortality. Nevertheless, the intricate relationships between metal exposure, inflammation and mortality remain unknown. We included 3741 adults with measurements of ten urinary heavy metals in the National Health and Nutritional Examination Survey (NHANES) 2005-2010, followed up to December 31, 2019. Low-grade systemic inflammation was evaluated by various markers, including C-reactive protein (CRP) and ratios derived from regular blood tests. We assessed associations between heavy metal and all-cause mortality using multivariate COX regressions. Then we assessed the mediation effect of low-grade systemic inflammation on the associations via Sobel Test. To gauge the systemic inflammatory potential of the multi-metal mixture and its correlation with all-cause mortality, a Metal Mixture Inflammatory Index (MMII) was developed using reduced rank regression (RRR) models. The association between MMII and all-cause mortality was explored via multivariate COX regressions. Cadmium, antimony and uranium displayed positive associations with mortality, with hazard ratios (HR) ranging from 1.18 to 1.46 (all P-FDR < 0.05). Mediation analyses revealed that the associations between specific heavy metals (cadmium and antimony) and mortality risk were slightly mediated by the low-grade systemic inflammation markers, with mediation proportions ranging from 3.11 % to 5.38 % (all P < 0.05). MMII, the weighted sum of 9 heavy metals, significantly predicted platelet-to-lymphocyte ratio (PLR) and CRP (β = 0.10 and 1.16, all P < 0.05), was positively associated with mortality risk (HR 1.28, 95 % CI 1.14 to 1.43). Exposure to heavy metals might increase all-cause mortality, partly mediated by low-grade systemic inflammation. MMII, designed to assess the potential systemic inflammatory effects of exposure to multiple heavy metals, was closely related to the all-cause mortality risk. This study introduces MMII as an approach to evaluating co-exposure and its potential health effects comprehensively.

The anterior scleral thickness in primary open-angle glaucoma with high myopia

Purpose

This study aimed to investigate and compare the anterior scleral thickness (AST) among high myopia (HM), primary open-angle glaucoma (POAG), and POAG with HM (HMPOAG) groups.

Methods

Thirty-two HM eyes, 30 POAG eyes, and 31 HMPOAG eyes were included. The Schlemm's canal (SC) area, trabecular meshwork (TM) thickness, scleral spur (SS) length, and AST were measured using swept-source optical coherence tomography. AST was measured at 0 mm (AST0), 1 mm (AST1), 2 mm (AST2), and 3 mm (AST3) from SS.

Results

The HMPOAG group had significantly thinner AST, SS length, and TM thickness than the HM and POAG groups (all p < 0.05). In addition, the SC area of the HMPOAG group was also significantly smaller than that of the HM group (p < 0.001).

Conclusion

The HMPOAG group had the thinnest AST, shortest SS, thinnest TM, and smallest SC. The thinnest AST might contribute to the shortest SS, and further to the thinnest TM and smallest SC in the HMPOAG group. AST might be a novel clinical indicator in the prediction and evaluation of POAG.

Application of mendelian randomization in ocular diseases: a review

Ocular disorders can significantly lower patients' quality of life and impose an economic burden on families and society. However, for the majority of these diseases, their prevalence and mechanisms are yet unknown, making prevention, management, and therapy challenging. Although connections between exposure factors and diseases can be drawn through observational research, it is challenging to rule out the interference of confounding variables and reverse causation. Mendelian Randomization (MR), a method of research that combines genetics and epidemiology, has its advantage to solve this problem and thus has been extensively utilized in the etiological study of ophthalmic diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides approaches for the investigation of related mechanisms as well as the intervention strategies.

Effect of intraocular pressure reduction on progressive high myopia (PHM study): study protocol of a randomised controlled trial

BACKGROUND

In adult patients with high myopia (HM), progressive axial elongation poses a significant risk for the development of subsequent ocular complications that may lead to visual impairment. Effective strategies to reduce or prevent further axial elongation in highly myopic adult patients have not been available so far. Recent studies suggested that medically lowering intraocular pressure (IOP) may reduce axial elongation.

OBJECTIVE

This clinical randomised controlled trial (RCT) aims to evaluate the efficacy of medical IOP reduction in adult patients with progressive HM (PHM).

TRIAL DESIGN

Single-centre, open-label, prospective RCT.

METHODS

This RCT will recruit 152 participants with PHM at the Zhongshan Ophthalmic Center (ZOC). Randomised in a ratio of 1:1, participants will receive IOP-lowering eyedrops (intervention group) or will be followed without treatment (control group) for 12 months. Follow-up visits will be conducted at 1, 6 and 12 months after baseline. Only one eye per eligible participant will be included for analysis. The primary outcome is the change in axial length (AL) within the study period of 12 months. Secondary outcomes include the incidence and progression of visual field (VF) defects, changes in optic disc morphology and incidence and progression of myopic maculopathy. Difference in AL changes between the two groups will be analysed using linear regression analysis. For the secondary outcomes, a multifactor Poisson regression within a generalised linear model will be used to estimate the relative risk of progression in VF defects and myopic maculopathy, and the rate of thinning in retinal nerve fibre layer and ganglion cell-inner plexiform will be assessed through Kaplan-Meier curves and log-rank tests.

ETHICS AND DISSEMINATION

Full ethics approval for this trial has been obtained from the Ethics Committee of ZOC, Sun Yat-sen University, China (ID: 2023KYPJ110). Results of this trial will be disseminated through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

NCT05850936.

The development and the genetic diseases of the ciliary body

The ciliary body, located at the junction of the choroid and iris, is crucial in the development of the embryonic eye. Notch2 signalling, Wnt signalling, transforming growth factor β (TGF-β) signalling, and Pax6 signalling are critical for coordinating the ciliary body formation. These signalling pathways are coordinated with each other and participate in the ciliary body development, ensuring the precise formation and optimal functioning of the eye structure. Although rare, ciliary body hypoplasia, ciliary tumours, and genetic-related iritis indicate the intricate nature of ciliary body development. Given the ciliary body's important biological significance and potential medical relevance, we aim to provide a comprehensive overview of the developmental molecular mechanisms governing ciliary body formation and function. Here, we focus on the intricate signalling pathways governing ciliary body development and corresponding genetic ciliary diseases.

Higher intraocular pressure is associated with slower axial growth in children with non-pathological high myopia

OBJECTIVES

To investigate the association between intraocular pressure (IOP) and axial elongation rate in highly myopic children from the ZOC-BHVI High Myopia Cohort Study.

METHODS

162 eyes of 81 healthy children (baseline spherical equivalent: -6.25 D to -15.50 D) aged 7-12 years with non-pathological high myopia were studied over five biennial visits. The mean (SD) follow-up duration was 5.2 (3.3) years. A linear mixed-effects model (LMM) was used to assess the association between IOP (at time point t-1) and axial elongation rate (annual rate of change in AL from t-1 to t), controlling for a pre-defined set of covariates including sex, age, central corneal thickness, anterior chamber depth and lens thickness (at t-1). LMM was also used to assess the contemporaneous association between IOP and axial length (AL) at t, controlling for the same set of covariates (at t) as before.

RESULTS

Higher IOP was associated with slower axial growth (β = -0.01, 95% CI -0.02 to -0.005, p = 0.001). There was a positive contemporaneous association between IOP and AL (β = 0.03, 95% CI 0.01-0.05, p = 0.004), but this association became progressively less positive with increasing age, as indicated by a negative interaction effect between IOP and age on AL (β = -0.01, 95% CI -0.01 to -0.003, p = 0.001).

CONCLUSIONS

Higher IOP is associated with slower rather than faster axial growth in children with non-pathological high myopia, an association plausibly confounded by the increased influence of ocular compliance on IOP.

Causal Associations of Glaucoma and Age-Related Macular Degeneration with Cataract: A Bidirectional Two-Sample Mendelian Randomisation Study

Common age-related eye disorders include glaucoma, cataract, and age-related macular degeneration (AMD); however, little is known about their relationship with age. This study investigated the potential causal relationship between glaucoma and AMD with cataract using genetic data from multi-ethnic populations. Single-nucleotide polymorphisms (SNPs) associated with exposure to cataract were selected as instrumental variables (IVs) from genome-wide association studies using meta-analysis data from BioBank Japan and UK Biobank. A bidirectional two-sample Mendelian randomisation (MR) study was conducted to assess the causal estimates using inverse variance weighted, MR-Egger, and MR pleiotropy residual sum and outlier tests. SNPs with (p < 5.0 × 10-8) were selected as IVs for cataract, primary open-angle glaucoma, and AMD. We found no causal effects of cataract on glaucoma or AMD (all p > 0.05). Furthermore, there were no causal effects of AMD on cataract (odds ratio [OR] = 1.02, p = 0.400). However, glaucoma had a substantial causal effect on cataract (OR = 1.14, p = 0.020). Our study found no evidence for a causal relationship of cataract on glaucoma or AMD and a casual effect of AMD on cataract. Nonetheless, glaucoma demonstrates a causal link with cataract formation, indicating the need for future investigations of age-related eye diseases.

Reversal of severe myopia by 24 years of hypotony with subsequent stable refraction after 2 years of normal intraocular pressure

Purpose

To report sustained axial length shortening and hyperopic shift (refraction changed from -8 to -2 diopters) induced by 24 years of profound IOP (intraocular pressure) reduction with subsequent refractive stability 2 years after IOP rose to 11-17 mm Hg.

Observations

A 25-year-old woman with elevated episcleral venous pressure glaucoma underwent non-penetrating trabeculectomy and subsequent laser goniopuncture in her left eye. She had chronically low IOP (1-12 mm Hg) for the next 24 years. Hypotony maculopathy was present in postoperative years 13-14 and 18-24 but resolved at age 49 when emesis-induced iris prolapse obstructed the filtering passage and transiently raised IOP to 40. Medical management and iridectomy with flap suturing stabilized IOP between 11 and 17 mm Hg.Refraction before OS trabeculectomy was OD -7.50/OS -9.00. In postoperative year 24 spherical equivalent phakic refraction was OD -9.00/OS -1.50. Biometry 1 year after resolution of hypotony showed axial lengths OD 24.8, OS 22.6 mm. Cataract surgery was performed in postoperative years 24/26 (OD/OS) with Tecnis DCBOO intraocular lenses of powers 14.0/21.5 diopters; postoperative refractions, 2 years after OS IOP rose to 11-17 mm Hg, were OD +0.25-0.50 x 015/OS -0.75-1.25 x 160 with 20/25 corrected acuity in each eye.Cardiovascular symptoms 24 years after the onset of her glaucoma led to a diagnosis of severe pulmonary hypertension.

Conclusions and importance

This case demonstrates that 2 decades of chronic IOP reduction can reverse myopia (by > 2 mm reduction in axial length) with subsequent refractive stability 2 years after IOP normalization. In addition, the case shows that ocular signs of pulmonary hypertension may precede cardiovascular signs by 2 decades.

Causal relationships between Gut microbiota and primary open-angle Glaucoma: A Mendelian randomization and mediation analysis of Glaucoma endophenotypes

Primary open-angle glaucoma (POAG) is a widespread condition responsible for irreversible blindness, and its prevalence is expected to increase substantially in the coming decades. Despite its significance, the exact cause of POAG remains elusive, necessitating a comprehensive exploration of its pathogenesis. Emerging research suggests a potential link between alterations in gut microbiota composition and POAG. However, establishing causality in these associations remains a challenge. In this study, we employed Mendelian randomization (MR) analysis to investigate the potential causal relationships between gut microbiota (GM) and POAG. Significant bacteria taxa were further analyzed with POAG endophenotypes. We utilized data from genome-wide association studies (GWAS) for GM and POAG, as well as for glaucoma endophenotypes, including intraocular pressure (IOP), retinal nerve fiber layer (RNFL) thickness, vertical cup-to-disc ratio (VCDR), and central corneal thickness (CCT). Univariable, multivariable MR and mediation effect analysis were conducted. Our analysis revealed that certain taxa, including phylum Euryarchaeota, genus Odoribacter, Rumnicoccaceae UCG009, Ruminiclostridium9, unknown genus id.2071, and Eubacterium rectale group, were associated with an increased risk of POAG. On the other hand, family Victivallaceae, Lacchnospiraceae, genus Lachnoclostridium, Oscillospira, Ruminococcaceae UCG011, Alloprevotella, and Faecalibacterium were found to be associated with a decreased risk of POAG. Furthermore, some of these taxa were found to be connected to glaucoma endophenotypes. Through further multivariable MR analysis, it was determined that IOP, VCDR, and CCT might played mediating roles between GM and POAG. In conclusion, this study utilizes MR analysis to elucidate potential causal associations between GM and POAG, providing insights into specific GM taxa that influence POAG risk and related endophenotypes. These findings emphasize the potential role of the gut microbiota in the pathogenesis of POAG and pave the way for future research and therapeutic interventions.

Genetic associations and potential mediators between psychiatric disorders and irritable bowel syndrome: a Mendelian randomization study with mediation analysis

Objective

Potential causal associations between psychiatric disorders and irritable bowel syndrome have been demonstrated in observational studies; however, these studies are susceptible to underlying confounding and reverse causation biases. We aimed to assess the causal effects of psychiatric disorders on irritable bowel syndrome (IBS) and the potential mediators from a genetic perspective by conducting a Mendelian randomization (MR) study with mediation analysis.

Method

Genetic instruments associated with psychiatric disorders, potential mediators, and IBS were obtained from large-scale genome-wide association studies (GWAS). Three MR methods - the inverse-variance weighted (IVW) method, MR-Egger method, and weighted median method, were used to investigate causal association estimates. Heterogeneity among different genetic instrumental variables (IVs) was assessed using Q tests. Additionally, the MR-PRESSO and MR-Pleiotropy methods were used to verify horizontal pleiotropy and detect outliers that might bias the results, which were removed from further analysis. Consequently, we used MR mediation analysis to investigate potential mediators in the causal associations between psychiatric disorders and IBS.

Results

MR provided evidence of the causal effects of genetically predicted broad depression, major depressive disorder (MDD), anxiety disorder, post-traumatic stress disorder (PTSD), and schizophrenia on IBS. The results of MR mediation analysis demonstrated that the reduction in acetate levels mediated 12.6% of the effects of broad depression on IBS; insomnia mediated 16.00%, 16.20%, and 27.14% of the effects of broad depression, MDD, and PTSD on IBS, respectively; and the increase in blood β-hydroxybutyrate levels mediated 50.76% of the effects of schizophrenia on IBS.

Conclusion

Our study confirmed the brain-gut axis involvement and potential modulators in the pathophysiology of psychiatric disorder-induced IBS from a genetic perspective, and suggests potential therapeutic targets for the disrupted brain-gut axis.

Thyroid function and epilepsy: a two-sample Mendelian randomization study

Background

Thyroid hormones (THs) play a crucial role in regulating various biological processes, particularly the normal development and functioning of the central nervous system (CNS). Epilepsy is a prevalent neurological disorder with multiple etiologies. Further in-depth research on the role of thyroid hormones in epilepsy is warranted.

Methods

Genome-wide association study (GWAS) data for thyroid function and epilepsy were obtained from the ThyroidOmics Consortium and the International League Against Epilepsy (ILAE) Consortium cohort, respectively. A total of five indicators of thyroid function and ten types of epilepsy were included in the analysis. Two-sample Mendelian randomization (MR) analyses were conducted to investigate potential causal relations between thyroid functions and various epilepsies. Multiple testing correction was performed using Bonferroni correction. Heterogeneity was calculated with the Cochran's Q statistic test. Horizontal pleiotropy was evaluated by the MR-Egger regression intercept. The sensitivity was also examined by leave-one-out strategy.

Results

The findings indicated the absence of any causal relationship between abnormalities in thyroid hormone and various types of epilepsy. The study analyzed the odds ratio (OR) between thyroid hormones and various types of epilepsy in five scenarios, including free thyroxine (FT4) on focal epilepsy with hippocampal sclerosis (IVW, OR = 0.9838, p = 0.02223), hyperthyroidism on juvenile absence epilepsy (IVW, OR = 0.9952, p = 0.03777), hypothyroidism on focal epilepsy with hippocampal sclerosis (IVW, OR = 1.0075, p = 0.01951), autoimmune thyroid diseases (AITDs) on generalized epilepsy in all documented cases (weighted mode, OR = 1.0846, p = 0.0346) and on childhood absence epilepsy (IVW, OR = 1.0050, p = 0.04555). After Bonferroni correction, none of the above results showed statistically significant differences.

Conclusion

This study indicates that there is no causal relationship between thyroid-related disorders and various types of epilepsy. Future research should aim to avoid potential confounding factors that might impact the study.

Understanding the complex genetics and molecular mechanisms underlying glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Currently the only effective treatment for glaucoma is to reduce the intraocular pressure, which can halt the progression of the disease. Highlighting the importance of identifying individuals at risk of developing glaucoma and those with early-stage glaucoma will help patients receive treatment before sight loss. However, some cases of glaucoma do not have raised intraocular pressure. In fact, glaucoma is caused by a variety of different mechanisms and has a wide range of different subtypes. Understanding other risk factors, the underlying mechanisms, and the pathology of glaucoma might lead to novel treatments and treatment of underlying diseases. In this review we present the latest research into glaucoma including the genetics and molecular basis of the disease.

The alterations in ocular biometric parameters following short-term discontinuation of long-term orthokeratology and prior to subsequent lens fitting: a preliminary study

PURPOSE

To investigate the alterations in biometric parameters among Chinese adolescents over an extended period of wearing orthokeratology lenses, as well as the subsequent changes after a one-month cessation of lens usage prior to the secondary lens fitting.

METHODS

Twenty-four myopic patients aged 7-14 were enrolled in this 37-month prospective observational study. Ocular biometric parameters were measured in the study. Ocular biometric parameters were assessed, and the utilization of Generalized Estimating Equations (GEE) was employed in the analysis to address the correlation between the two eyes of each participant.

RESULTS

The axial length (AL) increased by 0.55 mm after 36 months of lens wearing and further increased to 0.62 mm at the 37-month follow-up compared to the initial measurement. The differences in AL elongation per month between the 37-month time point and the 12-, 24-, and 36-month marks of lens wearing were found to be statistically significant (p12-month = 0.001; p24-month = 0.003; p36-month = 0.001). Following the cessation of lens wear for 1 month, there was no significant complete recovery observed in the flat and steep keratometry values. However, the intraocular pressure and anterior chamber depth returned to their baseline levels.

CONCLUSIONS

The AL elongation undergoes alterations during temporary discontinuation of lenses, with the flat and steep keratometry measurements remaining significantly flatter compared to the baseline. However, the intraocular pressure and anterior chamber depth return to their initial levels after one month of lens cessation.

The Role of Polyunsaturated Fatty Acids in Osteoarthritis: Insights from a Mendelian Randomization Study

The prior observational research on the impact of polyunsaturated fatty acid (PUFA) supplementation on osteoarthritis (OA) patients had yielded inclusive outcomes. This study utilized the Mendelian randomization (MR) approach to explore potential causal relationships between PUFAs and OA. The MR study was performed using GWAS summary statistics for PUFAs, encompassing omega-3 and omega-6 fatty acids, and for knee OA (KOA) and hip OA (HOA). The primary inverse-variance-weighted (IVW) method and two supplementary MR approaches were used to establish robust causality. Heterogeneity and horizontal pleiotropy were assessed using Cochrane's Q and MR-Egger intercept tests. Additionally, a range of sensitivity analyses were conducted to strengthen the precision and reliability of the results. The IVW method indicated a potential genetic association between omega-3 fatty acids and KOA risk (odd ratio (OR) = 0.94, 95% confidence interval (CI): 0.89-1.00, p = 0.048). No significant correlation was found between omega-3 levels and HOA. Moreover, genetically predicted higher levels of omega-6 fatty acids were associated with a decreased risk of KOA (OR = 0. 93, 95% CI: 0.86-1.00, p = 0.041) and HOA (OR = 0.89, 95% CI: 0.82-0.96; p = 0.003). The MR-Egger intercept evaluation showed no horizontal pleiotropy affecting the MR analysis (all p  >  0.05). Our findings supported the causal relationship between PUFAs and OA susceptibility and offered a novel insight that high omega-6 fatty acids may reduce the risk of KOA and HOA. These results underscore the importance of maintaining optimal levels of PUFAs, particularly omega-6 fatty acids, in individuals with a genetic predisposition to OA. Future research is necessary to validate these findings and elucidate the underlying mechanisms involved.

Addressing Glaucoma in Myopic Eyes: Diagnostic and Surgical Challenges

Epidemiological and genetic studies provide strong evidence supporting an association between myopia and glaucoma. The accurate detection of glaucoma in myopic eyes, especially those with high myopia, remains clinically challenging due to characteristic morphologic features of the myopic optic nerve in addition to limitations of current optic nerve imaging modalities. Distinguishing glaucoma from myopia is further complicated by overlapping perimetric findings. Therefore, longitudinal follow-up is essential to differentiate progressive structural and functional abnormalities indicative of glaucoma from defects that may result from myopia alone. Highly myopic eyes are at increased risk of complications from traditional incisional glaucoma surgery and may benefit from newer microinvasive glaucoma surgeries in select cases.

Association of Behavioral and Clinical Risk Factors With Cataract: A Two-Sample Mendelian Randomization Study

Purpose

To investigate the association of genetically determined primary open-angle glaucoma (POAG), myopic refractive error (RE), type 2 diabetes (T2D), blood pressure (BP), body mass index (BMI), cigarette smoking, and alcohol consumption with the risk of age-related cataract.

Methods

To assess potential causal effects of clinical or behavioral factors on cataract risk, we conducted two-sample Mendelian randomization analyses. Genetic instruments, based on common genetic variants associated with risk factors at genome-wide significance (P < 5 × 10-8), were derived from published genome-wide association studies (GWAS). For age-related cataract, we used GWAS summary statistics from our previous GWAS conducted in the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort (28,092 cataract cases and 50,487 controls; all non-Hispanic whites) or in the UK Biobank (31,852 cataract cases and 428,084 controls; all European-descent individuals). We used the inverse-variance weighted (IVW) method as our primary source of Mendelian randomization estimates and conducted common sensitivity analyses.

Results

We found that genetically determined POAG and mean spherical equivalent RE were significantly associated with cataract risk (IVW model: odds ratio [OR] = 1.04; 95% confidence interval [CI], 1.01-1.08; P = 0.018; per diopter more hyperopic: OR = 0.92; 95% CI, 0.89-0.93; P = 6.51 × 10-13, respectively). In contrast, genetically determined T2D, BP, BMI, cigarette smoking, or alcohol consumption were not associated with cataract risk (P > 0.05).

Conclusions

Our results provide evidence that genetic risks for POAG and myopia may be causal risk factors for age-related cataract. These results are consistent with previous observational studies reporting associations of myopia with cataract risk. This information may support population cataract risk stratification and screening strategies.

Circulating adipokine concentrations and the risk of venous thromboembolism: A Mendelian randomization and mediation analysis

Background: Previous observational studies have suggested that circulating adipokine concentrations are related to a greater risk of venous thromboembolism (VTE). However, it remained unclear whether these observations reflect causality.

Objective: This study aimed to investigate the causal relationship between circulating adipokine concentrations (including adiponectin, leptin, PAI-1, MCP-1, leptin receptor, and RETN) and the risk of VTE and its subtypes (DVT and PE) and to determine whether circulating adipokine concentrations are a mediator of venous thromboembolic events in obese patients.

Methods: We used Mendelian randomization (MR) analyses to determine the effects of the body mass index (BMI), adiponectin, leptin, PAI-1, MCP-1, leptin receptor, and RETN levels on VTE, DVT, and PE in a cohort of 11,288 VTE cases, 5,632 DVT cases, 5,130 PE cases, and 254,771 controls. We then assessed the proportion of the effect of obesity on VTE, DVT, and PE explained by circulating leptin levels.

Result: Genetically predicted higher BMI was related to increased VTE (OR = 1.45, p &lt; 0.001), DVT (OR = 1.63, p &lt; 0.001), and PE (OR = 1.37, p &lt; 0.001) risk, and higher circulating leptin levels increase odds of VTE (OR = 1.96, q &lt; 0.001), DVT (OR = 2.52, q &lt; 0.001), and PE (OR = 2.26, q = 0.005). In addition, we found that the causal effect between elevated serum adiponectin and the decreased risk of VTE (OR = 0.85, p = 0.013, q = 0.053) and PE (OR = 0.81, p = 0.032, q = 0.083) and between MCP-1 and the reduced risk of VTE (OR = 0.88, p = 0.048, q = 0.143) is no longer significant after FDR adjustment. In MR mediation analysis, the mediation effect of circulating leptin levels in the causal pathway from BMI to PE was estimated to be 1.28 (0.95–1.71, p = 0.10), accounting for 39.14% of the total effect.

Conclusion: The circulating leptin level is a risk factor for VTE, DVT, and PE, but it might be a potential mediator of BMI on the risk of PE, and thus, interventions on the circulating leptin level in obesity might reduce the risk of PE. Adiponectin is a potential protective factor for both VTE and PE.

Causal Association between Iritis or Uveitis and Glaucoma: A Two-Sample Mendelian Randomisation Study

Recent studies have suggested an association between iritis or uveitis and glaucoma. This study investigated the causal relationship between glaucoma and iritis and uveitis as exposures in a multi-ethnic population. Single-nucleotide polymorphisms associated with exposures to iritis and uveitis from the genome-wide association study (GWAS) data of Biobank Japan (BBJ) and the meta-analysis data from BBJ and UK Biobank (UKB) were used as instrumental variables (IVs). The GWAS dataset for glaucoma was extracted from the meta-analysis data (n = 240,302) of Genetic Epidemiology Research in Adult Health and Aging and UKB. The casual estimates were assessed with a two-sample Mendelian randomisation (MR) test using the inverse-variance-weighted (IVW) method, weighted median method, MR–Egger method, and MR-Pleiotropy Residual Sum and Outlier test. The IVW method revealed a significant causal association between iritis and glaucoma using IVs (p < 5.0 × 10−8) from the East Asian population (n = 2) (odds ratio [OR] = 1.01, p = 0.017), a significant association between iritis exposures (p < 5.0 × 10−8) in the multi-ethnic population (n = 11) (OR = 1.04, p = 0.001), and a significant causal association between uveitis exposures (n = 10 with p < 5.0 × 10−8) and glaucoma in the multi-ethnic population (OR = 1.04, p = 0.001). Iritis and uveitis had causal effects on glaucoma risk based on IVs from the multi-ethnic population. These findings imply that the current classifications of uveitic glaucoma and open-angle glaucoma overlap, indicating the need for further investigating these complex relationships.