The last litter of ferals that I rescued had the worst eyes I'd ever seen. They were so crusty, etc. and I was afraid they'd go blind. When I expressed this concern to my vet, he said that Mama cat will clean their eyes and that they have something in their saliva that heals them. Sho nuf, Mama took the kittens and moved them for about 3 weeks. I was frantic searching for them and finally had to just let nature take its course. When they came back, their eyes were clear. But if you can take Mama to a no kill shelter or at least trap her and have her spayed, it will make a huge difference. I know money is tight (been there so often I've lost count) but the cat population will grow beyond belief and very quickly and then you'll be overwhelmed and you won't know what to do. Meanwhile the cats will continue to breed and be constantly hungry and get sick. I don't want to frighten or alarm you, just forewarn you that this could get out of hand very quickly. Scrape some bucks together, trap Mama, get her spayed and life will be oh so much easier for her and her kittens. And for you. Good luck.