Fig. 2
Direct Acyclic Graph illustrating core MR assumptions. The three core MR assumptions are: (i) the genetic instrument is robustly associated with the drug target, (ii) the genetic instrument is independent of any confounders, (iii) the genetic instrument influences IOP/POAG exclusively via the drug target (or factors downstream of the drug target). In the Wald ratio method, the instrument-outcome association (BGY) is divided by the instrument-exposure association (BGX). IOP intraocular pressure, POAG primary open-angle glaucoma. The broken lines represent forbidden pathways that constitute violations of the MR assumptions