TY - JOUR T1 - Case–control or cohort study? JF - British Journal of Ophthalmology JO - Br J Ophthalmol SP - 1175 LP - 1175 DO - 10.1136/bjo.2011.203141 VL - 95 IS - 8 AU - Tamhane Ashutosh AU - Gerald McGwin Y1 - 2011/08/01 UR - http://bjo.bmj.com/content/95/8/1175.1.abstract N2 - In a recently published article by Chandra et al the authors have stated that they conducted a ‘case-controlled’ study to examine the anticoagulant effect of warfarin in vitreoretinal surgery.1 However, this study was conducted on a cohort of patients receiving pars plana vitrectomy (PPV); 60 patients who received warfarin (exposure) on the day of … ER -