It is common to find a small amount of crust in the corners of your eyes upon waking. This substance, often called “sleep” or “rheum,” is a natural part of the eye’s self-cleaning process. It typically consists of mucus, oil, dead skin cells, and dust that accumulates while you sleep.
The Science of Eye Discharge
Normal eye crust forms from the eye’s continuous lubrication and cleansing mechanisms. Throughout the day, blinking spreads tears across the eye’s surface, washing away debris and keeping the eyes moist. These tears contain water, mucus, and oils, which help maintain eye health and clarity.
During sleep, the eyes are closed, and blinking ceases, preventing the natural drainage of these tears and accumulated particles. The meibomian glands produce an oily substance called meibum that prevents tears from evaporating too quickly. This oily secretion, along with mucus, traps small foreign particles, dust, and dead skin cells.
As these substances collect, the watery components of the tears evaporate, leaving behind a concentrated, dried residue. This residue is the eye crust you observe upon waking. Normal sleep crust typically appears clear, whitish, or a light yellow, and has a slightly sticky or flaky consistency. Its appearance indicates the eye’s healthy process of clearing away irritants and cellular debris.
Other types of discharge can also occur. Watery discharge primarily consists of excess tears, often in response to irritation or allergens. Thick, pus-like discharge indicates an immune response to an infection. Stringy discharge, often containing a higher concentration of mucus, can be associated with certain inflammatory conditions.
When Crusting Signals a Problem
While some eye crust is normal, changes in its amount, color, or consistency can indicate an underlying issue. Excessive or unusual eye discharge, especially when accompanied by other symptoms, warrants attention.
Bacterial Conjunctivitis
Bacterial conjunctivitis, commonly known as pink eye, often causes thick, greenish-yellow discharge that can glue the eyelids shut. This infection also typically presents with redness in the white part of the eye, irritation, and sometimes a gritty sensation.
Viral Conjunctivitis
Viral conjunctivitis, another form of pink eye, usually produces a more watery or stringy discharge. It is often accompanied by a red, irritated eye and light sensitivity.
Allergic Conjunctivitis
Allergic conjunctivitis, triggered by allergens, typically results in very itchy eyes and clear, watery discharge. The eyes may appear swollen and red, and the itching can be intense.
Blepharitis
Blepharitis, an inflammation of the eyelids, leads to chronic crusting along the lash line, often described as dandruff-like flakes. This condition can cause red, itchy, and swollen eyelids, along with a burning sensation and a feeling of foreign material in the eye.
Dry Eye Syndrome
Dry eye syndrome can also lead to crusting, as the eyes try to compensate for insufficient tear production or poor tear quality. This sometimes results in stringy mucus or excessive watery discharge followed by dryness.
Styes and Chalazia
Styes and chalazia, which are lumps on the eyelid, can also cause localized crusting. A stye is a painful, red bump that forms when an oil gland becomes infected, leading to discharge. A chalazion is a non-infectious, typically painless bump from a blocked oil gland, which can sometimes cause mild crusting.
Blocked Tear Ducts
Blocked tear ducts can cause tears to back up and spill over, leading to persistent watery discharge and sometimes sticky crusting.
Effective Management and Prevention
Managing eye crust begins with proper hygiene. When you wake up with crusted eyes, the safest way to clean them is by applying a warm compress. Soak a clean washcloth in warm water, wring it out, and gently place it over your closed eyes for several minutes. The warmth helps to soften the dried discharge, making it easier to remove without irritating the eye area.
After softening the crust, gently wipe it away with the warm washcloth, moving from the inner corner of the eye outwards. Avoid rubbing vigorously, as this can cause irritation or introduce bacteria. Always use a fresh part of the cloth for each eye to prevent cross-contamination. Discard the cloth and wash your hands thoroughly after cleaning.
Preventive measures focus on maintaining eye health and hygiene. Avoid touching your eyes, as hands can transfer bacteria and irritants. Regular hand washing, especially before and after touching your face, is also important. For contact lens wearers, adherence to cleaning and replacement schedules, as well as proper storage, helps prevent infections that lead to excessive discharge.
Always remove eye makeup thoroughly before going to bed to prevent blockages and reduce debris accumulation. If eye crusting is persistent, accompanied by redness, pain, blurred vision, increased sensitivity to light, or changes in the type of discharge, consult an eye care professional. These symptoms can indicate an infection or other condition that requires medical attention.