It's a chlamydia infection in the eyes, Very common in cats. Easily treated with some optical terramycin which you must pick up from your vet. The vet might be willing to sell you the antibiotics without seeing the kittens, worth a call. However it MUST be treated or the effects can be severe.
My barn cat Delilah was dumped in my barn, I am assuming due to the severity of the condition with the infection in her eyes left untreated. One eye was crusted over, oozing pus and sealed closed. That was the GOOD eye. Teh bad one, well, the optical orb was actually pushed out of the socket due to infection and swelling. Her eyeball was actually pushed out, hanging out by the optical nerve. If the people had paud the 10 bucks or so for the meds, she would have been fine. Instead they chose to neglect and then let her be someone else's problem. After about 300 bucks in vet bills which included a round of intravenous fluids, minor eye surgery to reset her eye and sew it closed (and later open it again), antibiotics, anti inflams and tons of daily care, this is the end result.
She has severe scarring in the "bad" eye, although the good one was a complete recovery. We did manage to save they eye though. She very nearly died twice.
Spend a little money on care, now, or refuse them and condemn them to pain and suffering.
Speed Racer may be harsh but she is right. You have a responsibility to provide treatment for the ill animals in your care, whether you brought them into the world intentionally or through lack of prevention. Either way - get it sorted now or euthanize them.