Introduction:The effects of cardiopulmonary bypass(CPB) on visual functions was sought by comparison of visual examinations in the preoperative and early postoperative periods of isolated coronary artery bypass grafting(CABG) operations with CPB.Methods: Twenty consequent patients (16 males, 4 females; average age 58.75±7.88years; range 45-69 years) operated for isolated CABG with CPB at the same centre by the same team were enrolled.All patient data were recorded prospectively.The patients were compared regarding vision defects, retinal vascular and other structural changes by examination of vision, fundus examination for retinal pathologies and retinal photography to verify retinal structural changes in preoperative and postoperative periods.The findings on the last preoperative and seventh postoperative days were analyzed.Results: Between the preoperative and postoperative examinations, visual acuity of the left eye (p=0.042),intraocular pressure of the right eye (p=0.008) and intraocular pressure of the left eye (p=0.004)were found statistically significantly higher.Intraocular pressure showed correlation with aortic cross clamp and intubation duration, which was not accepted as clinically significant.No structural defects were detected by biomicroscope.The findings of direct examination of fundus photographed preoperatively, remained unchanged postoperatively.No differences could be detected regarding arterial and venous structures, optic papilla, macula, and peripheral retinal structure between the preoperative and postoperative periods.Discussion and Conclusion: Maintaining careful cannulation and proper management of CPB in coordination with anaesthesiologist, CABG operations can be performed safely with CPB, since no undesired effects on preoperative and postoperative direct fundus examinations, retinal morphology, visual functions and consequently on cerebral functions in part were detected.