Genetically determined disturbances of the normal function of the eye are distributed in high frequencies in several breeds of dogs. Two groups of these disturbances are discussed; disturbances resulting from the aims of breeding and defects caused by mutant genes. Disturbances such as ectropion, entropion and trichiasis may be regarded as the results of aims of breeding. They have a polygenic background and can be reduced by selection against the undesired traits and by modification of the breed standards. The frequencies of defects caused by mutant genes such as PRA, cataract and PHTVL/PHPV can be effectively reduced by veterinary practitioners. They are expected to be able to explain the consequences of breeding with animals carrying these genes to their clients when patients with these defects are presented.