By cold in her eye I'm assuming you mean an eye infection.

Get the kitties to the vet. You don't want to mess around with an eye
infection.

In the mean time try warm damp compresses on the eye and see if you can
(gently) get some of the 'gunk' off.

The kitten MUST have antibiotic ointment in that eye. You will need
"Terramycin Ophthalmic Ointment" which I think your vet should sell
you without seeing the cat. At least mine will. It is also available
without prescription online or from my local feed store for about
$10.

Neglected you can have the eye swell and explode ( called cherry eye)
and the cost to remove that eye is not cheap, not to mention a blind,
disfigured cat. Don't wait. This is quite common and easy to cure if
it is treated promptly. Most rescue groups keep the ointment on hand.
There are always one or two who are going to need it. You put a 1/4
inch ribbon inside the eyelid a couple of time a day until it clears.
It should respond rapidly.  

BarB