The Nematodes Thelazia gulosa Railiet and Henry, 1910 and Thelazia skrjabini Erschov, 1928 as a Cause of Blindness in European Bison (Bison bonasus) in Poland.

Thelazia gulosa and T. skrjabini can be identified by morphometrical features. As thelasiosis might be a serious threat for protected population of European bison, further studies are needed of the epidemiology and pathology of this emerging parasitosis in Poland.