Advice/Help with a feral cat

Hello, We have had a feral cat coming to our house for around 3 years now. He is a tuxedo cat and clearly not neutered. We call him Mr. Gibbon's and he knows that there is always food, water and shelter on our porch for him so he is here pretty regularly. He currently has a very swollen eye and we are concerned about his overall health. Even though we have been feeding him for so long he won't let us get very close to him. Is there anyone out there that can help us trap him so we can get him some help? Thank you in advance! Susan