The development of nonarteritic anterior ischaemic optic neuropathy has been described to phosphodiesterase type 5 inhibitors. The aim of this systematic review and meta-analysis was to assess the risk of nonarteritic anterior ischaemic optic neuropathy associated with phosphodiesterase type 5 inhibitors exposure. A literature search was performed at MEDLINE, EMBASE, Toxline and VigiBase. Randomized controlled trials, observational studies, case reports and spontaneous reports describing nonarteritic anterior ischaemic optic neuropathy associated with phosphodiesterase type 5 inhibitors exposure were included. The risk of bias was assessed according to Centre for Reviews and Dissemination's (CRD) guidance. Data were analysed using descriptive statistics and meta-analysis. Four observational studies, 50 case reports and 608 spontaneous reports were identified. All observational studies evaluated males treated for erectile dysfunction. Treatment with phosphodiesterase type 5 inhibitors is not associated with an increased risk of definitive nonarteritic anterior ischaemic optic neuropathy [odds ratio (OR) 1.16; 95% CI 0.89, 1.52, p = 0.046; I 2 = 62.6%]. The methodological quality was assessed as good for three studies. Among case reports, 12 (23%) patients did not have risk factors to develop nonarteritic anterior ischaemic optic neuropathy. Thirtynine (78%) patients were treated for erectile dysfunction. A regular administration of phosphodiesterase type 5 inhibitors was observed in 24 (48%) case reports. All case reports were assessed as higher risk of bias. According to the available evidence, the treatment with phosphodiesterase type 5 inhibitors was not found to be associated with nonarteritic anterior ischaemic optic neuropathy. Further research is needed to study such association, including possible confounding factors.Key words: drug-related side effects and adverse reactions -ischaemic optic neuropathy -metaanalysis -ophthalmology -pharmacovigilance -phosphodiesterase 5 Inhibitors -systematic review Acta Ophthalmol. 2020: 98: 22-31