I have had 2 ferrets in the past that had one eye one a large hob which i found when out ferreting one day that had damage already to its eye , i also owned a small jill that took a kick from a rabbit when out working she lost the eye, the hob ended up a great worker and the jill has been one of the best ferrets ive ever owned . like some of the lads said clean the eye well for a few days you should know better when its clear and you can have a good look at it but dont let a one eyed ferret put you off mate they are no different than those with both eyes . hope all goes well no matter what