The role of vascular risk factors in glaucoma is increasingly being supported by the literature, with the association between low ocular perfusion pressure (PP) and glaucoma being the most consistent result. However, we need to be cautious when interpreting these results and consider all possible confounders in the observed associations. While we assess PP through its principal components, the weight of intraocular pressure (IOP) and blood pressure (BP) in the PP equation remains unknown. Also, the role of PP in glaucoma needs to be elucidated with regards to IOP and BP fluctuation during the 24hour period and the effect of IOP-lowering and BP-lowering treatment. The complexity of the interaction of PP with other potential risk factors for glaucoma means that PP cannot be currently considered in the assessment of an individual patient. The role of PP in glaucoma warrants further research and randomized clinical trials assessing PP should include vision and/or structure preservation as end-points and ideally address all of the above issues.