Hello, this is Dr. Bruce and I would like to help you with your girl.
I'm sorry to hear that she is having this issue.
I would assume that she has been diagnosed with dry eye since she is on the optimmune. Please give me more information about this. How long ago was she diagnosed? Has the optimmune helped at all? Has she ever been on the medication twice per day?
When was the last time her eyes were rechecked? Did the doctor stain the eyes looking for any scratches on the surface (cornea)?
What color is the mucous that is in the eyes?
Dry eye can be very painful and can lead to severe infections of the eye and surrounding tissue. Often, dogs will scratch and rub at the eyes and need to wear a cone to protect the eyes. Is she rubbing or scratching at the eyes? If so, then you need to protect the eyes with a cone.
If it is at all possible, I would like to see what the eyes look like. If you could take a few pictures and upload them to this site, that would help a lot for me to assist you.
Have the eyes worsened lately, or have they been a problem all along? If the eyes had been doing well, and just recently became covered with mucous, then it is likely that she has a secondary infection of the eyes and will need additional medication to treat the infection.
I look forward to your response to my questions, and hopefully, a few photos to help me give you a complete answer.