Have you tried saline rinses? You can buy a product called Bausch & Lombs Eye Rinse at most any pharmacy, some grocery stores, and sometimes they will carry a generic brand that is a few dollars cheaper. It is much less expensive than prescription eye drops or other drops like clear eyes (which you should not use if you are - clear eyes, visine, constrict the blood vessels in the eyes and will cause discomfort and this irritation can lead to the eyes secreting stringy mucous). Many people don't realize this, and they increase their eye problems by using these products (clear eyes, visine) to 'get the red out'. They should never be used more than once or twice a month.
I understand that this intervention sounds simple (using eye rinse 2 to 3 times daily) but sometimes health care providers over look the simple interventions, being trained to treat serious disease as we tend to be. When we evolved we lived by oceans and our eyes and sinuses were rinsed frequently by sea water (which has the similar percentage of sodium as our body fluids, including our tears). The Eye Rinse products also are a saline solution similar to the percentages of our tissues. Flushing your eyes with a stream from the bottle 2 to 3 times a day may improve your condition remarkably. It should at least make you more comfortable no matter what, as it will remove any potential allergens and other particles or mucos strings that may be contributing or a result of your problem.
Also, be sure if you have pets, that you are not allowing them on your pillow. If you have a cat or animal, make sure that your pillow is covered during the day when you are gone. Change your pillow case frequently, and make sure the detergent you are using is not creating an allergic reaction.
If the air quality is bad in your house or in your neighborhood consider getting a Hepa air filter to use in your home and/or office. They are no longer extremely expensive.
Please try this if you have not, and let me know what results you have.
Also, remember to be very careful not to touch the tip of the eye rinse bottle with your finger or the eye. This can take some practice, but you should be sure and use sterile technique with anything that is used in the eyes.