TY - JOUR T1 - NAION and treatment of erectile dysfunction: reply from Pfizer JF - British Journal of Ophthalmology JO - Br J Ophthalmol SP - 927 LP - 927 DO - 10.1136/bjo.2006.094375 VL - 90 IS - 7 AU - R E Sobel AU - J C Cappelleri Y1 - 2006/07/01 UR - http://bjo.bmj.com/content/90/7/927.1.abstract N2 - McGwin et al1 suggest that treatment of erectile dysfunction with sildenafil (Viagra) or tadalafil (Cialis), two phosphodiesterase inhibitors (PDE5-I), may increase the odds of non-arteritic anterior ischaemic optic neuropathy (NAION) in men with a history of myocardial infarction (MI) or hypertension (HTN). We believe, however, that this study is fraught with significant limitations (as the authors acknowledge) that preclude drawing any conclusions about this relation. Case-control studies are susceptible to several biases that must be carefully considered and controlled for in the study design, implementation, and analysis.2 For example, accurate and complete ascertainment of exposure is critical in a … ER -