Chronic dry eye is a disease of the surface of the eye that can happen when your eyes do not make enough tears or there is an issue with the tears that are made. One sign of dry eye disease is having mucus buildup in your eyes that appears stringy or thread-like. People may call this mucus different words, like goop, sleep, gunk, or crust.1
Whatever you call it, this sticky mucus serves a purpose. Mucus is a normal part of the 3 layers of your tears, known as the tear film. Tears help protect your eyes and keep them moist. Sometimes, extra mucus buildup in your eyes when you first wake up can be normal. But if you notice an increased amount of mucus or discharge from your eye, it could be an infection or other eye disorder.1
Where does this mucus come from?
The mucus from your eye comes from special cells called goblet cells. These cells are located on the conjunctiva, a very thin layer of clear tissue that covers part of the surface of the eye. The bulbar conjunctiva covers the white part of your eye, known as the sclera. The palpebral conjunctiva covers the inner surface of your eyelids.
Goblet cells normally secrete the mucus that makes up a layer of the tear film. The tear film has 3 layers: mucus, water, and oil. With every blink, these layers combine to coat the eye, protecting and hydrating it.2
What's a normal amount?
Waking up with “sleep” in your eyes and some crust in the corners of your eye can be normal. When you sleep, mucus and tear film can build up on your eye, leaving some crusts and extra mucus when you wake up. Large amounts of mucus or crusting in your eyes is not normal and may be a sign of an infection or other eye condition.1
Conjunctivitis, or inflammation of the conjunctiva, can be caused by an infection. Commonly known as “pink eye,” conjunctivitis causes an increased amount of mucus, pus, tears, or other discharge from the eye.1
Increased mucus or other discharge from the eye may also be caused by allergies, chemical exposures, and other contagious viruses or bacteria. Depending on the cause, this may need to be treated with special eye drops. The condition may also be contagious (can spread to others).1
What are the causes?
It might seem strange that dry eye disease can cause increased amounts of mucus on your eye. The reason behind this is all about balance.
Like so many other parts of your body, the surface of your eye depends on balance. The tear film covering the eye is a balance of oil, water, and mucus. Any problem with the eye can disrupt this balance.1
If the surface of the eye is abnormally dry, the eye sends a distress signal through the nerves, asking for more moisture. The result is an abnormal amount of tears or mucus. This is why dry eye can cause both a dry surface of the eye and an abnormally large amount of mucus or tears on its surface.1
Complications
Many times, extra mucus in your eyes is more annoying than it is harmful. There are situations where extra mucus can lead to other issues. One condition, known as mucus fishing syndrome, may happen if you pull at or “fish'' for the stringy mucus in your eyes. Pulling the mucus over time can damage your eye, causing vision issues or increasing the risk of infection in your eyes.3
Treatment
Treatment for too much mucus in the eye depends on the underlying cause of the condition. If it is caused by an infection, your doctor may need to treat it with a drug or special eye drops.
If eye mucus is caused by chronic dry eye, your doctor will look at what may be causing your dry eye symptoms in the first place. For example, if a drug is causing your symptoms, then stopping the drug or another drug may work in its place. Either way, talking to and seeing your eye doctor will help you get the treatment you need.
At home, a warm compress may help you remove mucus from your eye. Wash your hands frequently and avoid touching your eyes as much as possible.1