I feel for you, Antjexix. Really it's a matter of whether it is just the fact that he is blind, and may adjust, or whether his quality of life is too poor. Our elderly cat was diagnosed with thyroid trouble last year. She became increasingly confused, not being able to get into the litter tray and bumping into things. Sitting outside in the road in all weathers. One day she fell into a puddle by the house and couldn't get up. The next day DH took her to the vet and asked them to put her down, as we didn't want our lovely pet to suffer. The very young vet on duty persuaded him to bring her home, as "they have good days and bad days". The next day we took her again as she was obviously bewildered and deteriorating fast. Our usual vet saw her and agreed that if she were his cat he would put her to sleep. He was quite cross about the attitude of the young vet and agreed with us that no animal should be left to suffer. I hope though that Tom hasn't got to that stage and you can keep him for a while yet.