Causal associations between smoking and ocular diseases: a Mendelian randomization study.

PURPOSE: To explore the causal associations between smoking and ocular diseases using Mendelian randomization (MR).

METHODS

A two-sample Mendelian randomization (MR) analysis based on publicly.available genome-wide association studies were employed to infer the causal relationship. The effect estimates were calculated using the random-effects inverse-variance-weighted method.

RESULTS

Genetically predicted smoking was positively associated with cataract [Odds ratio (OR) ​= ​1.14, 95% confidence interval (CI): ​1.01-1.29; P ​= ​0.027], w-AMD [OR ​= ​1.41, 95%CI: ​1.06-1.88; P ​= ​0.019], diabetic retinopathy [OR ​= ​1.06, 95%CI: ​1.04-1.30; P ​= ​0.01], disorders of optic nerve and visual pathways [OR ​= ​1.46, 95% CI: ​1.00-2.14; P ​= ​0.049] in inverse variance weighted analysis. Suggestive evidence of an inverse association between smoking and myopia was also observed [OR=0.75, 95%CI: ​0.57-0.97; P ​= ​0.031]. No associations were observed for glaucoma, allergic conjunctivitis, pterygium, keratitis, scleritis and episcleritis. After performing weighted median and MR-Egger analysis, consistent results were observed. There was no horizontal pleiotropy in the two-sample MR analysis.

CONCLUSIONS

Smoking may increase the risks of cataract, w-AMD, diabetic retinopathy, disorders of optic nerve and visual pathways. And smoking may decrease the risk of myopia.