Until you can get her to a vet (asap), you can use a sterile compress made with cooled tea. Hold it against the eye for several minutes three times a day. This is according to a veterinary site. However, it is essential to get her to the vet in case of chlamydia or the herpes virus. Wash your hands thoroughly before AND after treating the cat. An eye infection can be an early symptom of serious ailments.
http://www.drcarolspets.com/p/57,75.html
http://www.drcarolspets.com/p/57,75.html