Eye discharge, medically known as rheum, is a natural process where your eyes clean themselves, and it often appears as “sleep” or “gunk” after waking up. The eye constantly produces a mix of mucus, oils, and tears to maintain a healthy surface, and this material is usually washed away by blinking throughout the day. When you sleep, the lack of blinking allows this normal debris to collect and dry in the corners of your eyes. While a small amount of clear or pale discharge is routine, any sudden change in the amount, color, or consistency of this mucus can signal an underlying health issue.
Understanding Normal Eye Discharge
The tear film covering the eye’s surface is composed of three layers: a mucous layer, a watery layer, and an outer oily layer. The inner mucous layer, produced by goblet cells in the conjunctiva, helps tears spread evenly across the eye. The outer oily layer, secreted by the meibomian glands along the eyelid margins, prevents the watery layer from evaporating too quickly.
“Sleep crust” or rheum is the dried accumulation of this tear film material, along with shed skin cells and dust, that collects overnight when the eyes are closed. Normal discharge is usually minimal, clear to slightly whitish, and crusty upon waking.
Infectious and Allergic Causes
A shift in discharge characteristics often points to an infection or allergy, with the consistency and color helping to identify the cause. Bacterial conjunctivitis, commonly called pink eye, typically produces a thick, sticky, pus-like discharge that is yellow or green. This discharge can be so significant that it causes the eyelids to be matted shut, particularly after sleeping.
Viral conjunctivitis presents with a clear, thin, and watery discharge. This watery discharge is often accompanied by a gritty sensation and considerable redness.
Allergic conjunctivitis, triggered by allergens like pollen or dander, results in discharge that is clear or white and often described as stringy or ropey. This condition is also marked by intense itching and significant eyelid swelling.
Chronic and Structural Contributors
Mucus production can also increase due to chronic conditions affecting the eye’s surface and drainage. Dry Eye Syndrome, for example, often causes stringy, white, or clear discharge, especially in the morning. This occurs because the body attempts to compensate for chronic dryness by overproducing the mucus component of tears, which then thickens and clumps together.
Blepharitis, an inflammation of the eyelid margins, leads to excessive crusting and discharge at the base of the eyelashes. This condition involves the dysfunction of the meibomian glands, causing thickened or unhealthy oils to be secreted, which contributes to sticky discharge.
In cases of blocked tear ducts (dacryocystitis), tears cannot drain properly, causing them to back up and pool. This stagnation results in a persistent, sticky discharge, which can be yellow or green if a secondary infection develops within the tear sac.
Recognizing Warning Signs
While most eye discharge is not a threat to vision, certain accompanying symptoms warrant professional medical attention. You should seek consultation if the discharge rapidly increases in volume or is consistently yellow, green, or gray, which strongly suggests a bacterial infection. Any discharge accompanied by severe eye pain, extreme sensitivity to light (photophobia), or a sudden change in vision requires immediate evaluation.
Other concerning signs include redness that is getting progressively worse, swelling of the eye or face, or if the discharge is bloody or brown. These symptoms can indicate a more serious condition, such as a corneal ulcer or a severe infection, that requires timely diagnosis and specific treatment.