Keeping my cat with eye problems

have a cat named Bandit. The people who had him before us told us he lost his eye when he was younger, but I don't know much else about what happened to him.
Lately, I've been struggling with a moral dilemma because the eye he lost constantly leaks gunk, and it breaks my heart seeing it like that. My roommate and I love him more than anything, but we honestly don't think we can afford to have it treated or fixed right now.
We always joke that he's our "stinky boy," and he brings us so much joy, but underneath the jokes, I'm worried. I just want to know what's truly best for him. I don't want him to be in pain or uncomfortable, and it hurts feeling like I might not be able to give him everything he needs. I'm just looking for some guidance so I can do right by him.