Keep with the salt solution, for a week.
Make sure you have the correct mesurements of salt to water - and do
not keep left over solution - use fresh solution evry time.
Use a clean whipe each time you whipe the eyes.

If the condition is accompanied by wheezing of breath, diahorriea or
losss of weight - take them to the vet ASAP.
Also, if other rats are showing symptoms too.

A good website to visit reguarding this is:
http://www.ratfanclub.org

The Rat Fan Club of America.

Good luck -
But, if it persists for longer than a week - or cleaning it only
seems to make it worse - see a vet.

(there a veterinary clinic websites in the "Bookmarks" of this group)