My Male 10yr Old Cat Seems Ill, I Need Advice, Can You Help?

My male cat is now 10 years old. He has been full of live up until 2 days ago. His pupils are blown and he struggles to see things properly, he has gone very thin even though he is fed two times a day. He has a regular supply of clean drinking water. His fur has gone very dull. He has no voice or at time very little and quiet. Has little appetitie or very slow to eat. Does not hear us very well, does not respond to his name. Regular wormed and defleed.