Aim. To estimate the influence of concomitant glaucoma (including that after surgery) on IOL power calculation accuracy before phacoemulsification. Materials and methods. 413 patients were included in the study divided in 4 groups: 1st - patients with cataract and no concomitant glaucoma (251 cases); 2nd - patients with cataract and primary open-angle glaucoma (POAG) on medical therapy (103 cases); 3rd - patients with cataract and prior trabeculectomy (42 cases); 4th - patients with cataract and primary angle-closure glaucoma (PACG) on medical therapy (17 cases). In all patients, the IOL power calculation was performed using optical biometry (IOL-Master 500). 1 month after surgery, desired refraction according to Barrett Universal II Formula and real obtained refraction estimated by automatic refractometry (Topcon-8800) were compared. Results. There was no significant difference between study groups 1-3 in IOL power calculation accuracy (the calculation error was -0.09 ± 0.39 D, -0.08 ± 0.45 D, -0.03 ± 0.49 D