Wood A, et al. - In two-sample Mendelian randomization analysis of data from a genome-wide association study, investigators studied the impact of the refractive error on the risk of age-related macular degeneration (AMD). They suggested a very limited influence of the refractive error on the risk of AMD. They found an association of a 1 D more hyperopic refractive error with an OR=1.080 raised risk of AMD. They observed minimal evidence from MR-Egger, MR-PRESSO, weighted median, and Phenoscanner-based sensitivity analyses and suggested that this result was biased by horizontal pleiotropy. Thus, strong associations between refractive error and AMD that are not consistently reported were likely to be the result of non-causal factors like stochastic variation, confounding or selection bias.