Treating Feral Kittens With Severe Eye Discharge?

I have been looking after a feral cat that has had 4 kittens. They're about 4-6 weeks old. 3 out of the 4 have severe eye discharge. I noticed it 3 days ago and it's getting worse. The runt's eyes are completely crusted shut and it hasn't been eating much. Previous Q and A's on the subject suggest Trifluridine which can be purchased from a vet without an examination. I've been consistently feeding mamma for over a year and she still hisses if I get too close. The kittens have picked up on her cues. What's the best way to go about getting drops in and cleaning around their eyes?