What about the color of the mucus, if it is white, it may be the symptom of blepharitis or bacterial conjunctivitis. These eyes disease would cause the keratitis. The reason of the symptom is the stimulation of environment; you would better to avoid the contact with stimulus or allergen such as pollen, paint or dust. Avoid rubbing your eyes with dirty hands that would bring bacterial into your eyes. As for the treatment, you would use clean water or artificial tear to clean the eyes, and then apply eyes with warm towel when eyes closed for three times one day, with more than half hours. The erythromycin eye ointment will also help to the treatment. If it would not help, please find the doctor to check. Hope you recovery soon!