and welcome to tcs
I did read your post earlier as I care for a colony of ferals but I haven't had any
experience of a blind 'outdoor' or blind 'feral' cat.
So I spoke to a good friend of mine about it who has, not really knowing all the details
to pass on to her(I,E age,when the cat went blind,was it blind from birth,has the cat lost comlete sight or partial?),She advised if you can trap this boy/girl and take the cat in?A vet should be able to determine how 'blind' the cat/kitten is.
If the cat is completely blind You would probably have to care for this cat yourself or find somebody dedicated enough to put in the time and patience this cat will need.
If it is a kitten will only survive for a short time outside(days) if it is not being cared for by its mother or fed by a carer and even then would be 'lucky' to survive any longer.
The chances of this cat surviving in the wild are very remote nearing impossible,unless it is taken in.
A shelter would almost 99.9% chance put this cat to sleep,so I would say if you can't
take the cat in yourself,try to find a charity that is dedicated to the welfare of ferals.
On a positive note though,blind ferals have been known to adapt to domestication quicker than sighted ferals
If you need any advice on how to bring round a blind feral,just let me know and I will ask my friend