Runny eyes can indicate that you cats are suffering from upper respiratory infections or even herpes virus.
I suggest that you see the vet with them as soon as you can. They will likely need antibiotics and supplemental care.
Keep in mind that fleas can contribute to kitten deaths so you need to treat any flea problems that you might have.
The good thing about litters of kittens is that most vets will see the whole litter and only charge for one office visit. Ask about this when you make your appointment.
Let me know if you still have questions.
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