Hi, My Yorkshire Terrier Cross Is Almost 16 Years Old,

Hi, my Yorkshire terrier cross is almost 16 years old, and suffers from pancreatitis but with diet he is stable, but recently he keeps bumping into everything, I know he cannot see properly but he has got much worse and keeps weeping on the carpet, his back is arched high, and he is off his food prob for about 5 or 6 days, thanks