Gook in eyes.......

I know its totally gross but Sassy has been getting gook in her eyes since she was a puppy. We took her to a vet a long time ago to see what was wrong. He said nothing was wrong. We went to two other vets for second opinions and one said nothing was wrong while the other siad it was allergies. He told us we had to clean it out with a comb. Well we do. Sometimes it gets so bad her eye is completely shut and my mom has to clean it. After we clean it out it comes back the next day. Does anyone know what it could be?Or is it allergies?
Thanks,
Alyssa

Allergies can cause the symptoms. But also likely are defects which can cause the eyelids (remember there's more than one for a dog) to roll into the cornea causing irritation. You might also want to consult with the Vet to see if an ocular corticosteroid might help. Do not use any human "eye drop" without consulting with your Vet first.

Well, we do give her eye drops the vet prescribed. And thanks for the help:)