Thank you for your question. I am sorry to hear you think your dog may be losing his eye sight. There are several conditions that may cause partial or complete loss of sight and some breeds of dog can be predisposed to certain diseases. I would take your little man to the vet who can perform a full ophthalmic examination to make sure everything is as it should be. If they find any abnormalities they can advise you on the next steps with regards to diagnostic tests and treatment.