Cigarette Smoke Triggers Loss of Corneal Endothelial Cells and Disruption of Descemet's Membrane Proteins in Mice

Long-term persistent exposure to cigarette smoke induces AhR driven corneal endothelial dysfunction in mice

Epidemiological studies show cigarette smoking enhances corneal endothelial dysfunction, but mechanisms remain unclear. Our study reveals that prolonged smoke exposure activates the aryl hydrocarbon receptor (AhR), increasing CYP1B1 expression and accelerating senescence and fibrosis in corneal endothelium, potentially reflecting adaptive responses to maintain corneal resilience. Although these molecular modifications indicate early endothelial dysfunction, no pathological changes were observed. The findings indicate that while chronic cigarette smoke exposure triggers initial molecular alterations and endothelial dysfunction, the progression to Fuchs endothelial corneal dystrophy likely requires additional environmental or genetic factors beyond smoke exposure alone.

TFOS Lifestyle: Impact of lifestyle challenges on the ocular surface

Many factors in the domains of mental, physical, and social health have been associated with various ocular surface diseases, with most of the focus centered on aspects of dry eye disease (DED). Regarding mental health factors, several cross-sectional studies have noted associations between depression and anxiety, and medications used to treat these disorders, and DED symptoms. Sleep disorders (both involving quality and quantity of sleep) have also been associated with DED symptoms. Under the domain of physical health, several factors have been linked to meibomian gland abnormalities, including obesity and face mask wear. Cross-sectional studies have also linked chronic pain conditions, specifically migraine, chronic pain syndrome and fibromyalgia, to DED, principally focusing on DED symptoms. A systematic review and meta-analysis reviewed available data and concluded that various chronic pain conditions increased the risk of DED (variably defined), with odds ratios ranging from 1.60 to 2.16. However, heterogeneity was noted, highlighting the need for additional studies examining the impact of chronic pain on DED signs and subtype (evaporative versus aqueous deficient). With respect to societal factors, tobacco use has been most closely linked to tear instability, cocaine to decreased corneal sensitivity, and alcohol to tear film disturbances and DED symptoms.

Effects of Type 2 Diabetes Mellitus and Smoking on Changes in Corneal Endothelial Morphology and Cell Density

PURPOSE

The purpose of this study was to compare the corneal endothelial morphology and cell density of diabetic smokers and nonsmokers with 50 to 70 age-matched healthy subjects and to determine whether smoking increases the effects of type 2 diabetes mellitus (DM) on these corneal parameters.

METHODS

This prospective cohort study included 200 patients who were assigned to 4 groups, including smokers with type 2 DM (group 1), nonsmokers with type 2 DM (group 2), healthy smokers (group 3), and healthy nonsmokers (control group, group 4). Noncontact specular microscopy was used to measure central endothelial cell density (ECD), coefficient of variation of cell area, percentage of hexagonal cells, and central corneal pachymetry (CCT).

RESULTS

According to the ECD and CCT values ( P < 0.001 and P = 0.013, respectively), a significant difference was observed between the groups. The mean ECD was lowest in diabetic smokers (1917 ± 399 cells/mm 2 ). Healthy smokers and diabetic smokers had significantly lower ECD compared with the control group ( P = 0.03 and P < 0.001, respectively). Healthy smokers and diabetic smokers had significantly lower ECD compared with diabetic nonsmokers ( P = 0.012 and P < 0.001, respectively). The cornea was significantly thicker in the diabetic smokers than in the control group ( P = 0.013).

CONCLUSIONS

The coexistence of DM and smoking causes a significant decrease in ECD and an increase in CCT. Cigarette smoking is more harmful to corneal endothelial cells than DM alone.

Risk Factors for Repeat Keratoplasty after Endothelial Keratoplasty - an IRIS® Registry Analysis

PURPOSE

To assess risk factors for repeat keratoplasty after endothelial keratoplasty (EK).

DESIGN

Retrospective cohort study METHODS: : EK procedures performed between 2013-2018 in the IRIS® Registry (Intelligent Research in Sight) were identified.

STUDY POPULATION

Patients aged 18 years and older who underwent EK.

MAIN OUTCOME MEASURES

1) Risk factors for repeat keratoplasty, and 2) complication rates after EK. A Kaplan-Meier survival analysis was used to determine the probability of repeat keratoplasty. A multivariable shared frailty survival model was used to assess risk factors.

RESULTS

59,344 procedures were identified in the registry, of which 30,600 EK procedures met the inclusion criteria for the analysis. The probability of repeat keratoplasty was 17.4% (95% CI:16.7-18.0%) at five years. Risk factors for repeat keratoplasty include post-operative re-bubbling procedure (HR 2.24, 95% CI:2.05-2.45); prior failed graft (HR 2.07, 95% CI:1.84-2.32) or bullous keratopathy (HR 1.47, 95% CI:1.33-1.61) versus Fuchs dystrophy as surgical indication; subsequent routine cataract surgery (HR 1.61, 95% CI:1.45-1.79); as well as subsequent (HR 1.53, 95% CI:1.39-1.69) and prior/concurrent (HR 1.23, 95% CI:1.11-1.36) glaucoma surgery or history of glaucoma (HR 1.24, 95% CI:1.14-1.35). Medicaid (HR 1.47, 95% CI:1.13-1.92), military/government (HR 1.29, 95% CI:1.03-1.60), Medicare Fee-for-Service (HR 1.17, 95% CI:1.05-1.31) or Medicare Managed (HR 1.17, 95% CI:1.01-1.36) insurances versus private insurance, as well as Black versus White race (HR 1.25, 95% CI:1.11-1.40) and smoking (HR 1.16, 95% CI:1.05-1.27) were also associated with an increased risk of undergoing repeat keratoplasty.

CONCLUSIONS

Black race, government-based insurance plans, and smoking were identified as independent factors associated with repeat keratoplasty in addition to history of glaucoma, glaucoma surgery, and prior graft failure or bullous keratopathy as surgical indication.

Examining the effects of cigarette smoke on mouse lens through a multi OMIC approach

Here, we report a multi OMIC (transcriptome, proteome, and metabolome) approach to investigate molecular changes in lens fiber cells (FC) of mice exposed to cigarette smoke (CS). Pregnant mice were placed in a whole-body smoke chamber and a few days later pups were born, which were exposed to CS for 5 hours/day, 5 days/week for a total of 3½ months. We examined the mice exposed to CS for CS-related cataractogenesis after completion of the CS exposure but no cataracts were observed. Lenses of CS-exposed and age-matched, untreated control mice were extracted and lens FC were subjected to multi OMIC profiling. We identified 348 genes, 130 proteins, and 14 metabolites exhibiting significant (p < 0.05) differential levels in lens FC of mice exposed to CS, corresponding to 3.6%, 4.3%, and 5.0% of the total genes, protein, and metabolites, respectively identified in this study. Our multi OMIC approach confirmed that only a small fraction of the transcriptome, the proteome, and the metabolome was perturbed in the lens FC of mice exposed to CS, which suggests that exposure of CS had a minimal effect on the mouse lens. It is worth noting that while our results confirm that CS exposure does not have a substantial impact on the molecular landscape of the mouse lens FC, we cannot rule out that CS exposure for longer durations and/or in combination with other morbidities or environmental factors would have a more robust effect and/or result in cataractogenesis.