Sleep Eye

Morning eye gunk (aka sleep eye, eye crust, mattering, etc; the medical term is actually rheum, the etymology of which comes from a Greek word meaning “flow”) is a common complaint, often reported by parents of a young infant. But why does it occur? And when is it abnormal? 

While we are awake, a continuous tear film keeps our eyes moist. Tears are produced by the lacrimal glands and drain medially into the puncta, then flow through the canaliculi to the lacrimal sac, and then through the nasolacrimal duct into the nose. The act of blinking uses this film to flush out normal mucus produced by the conjunctiva, oil from the meibomian glands, and other debris from the front surface of the eye. Because we don’t blink during sleep, eye discharge collects in the corners of our eyes and eyelashes. This discharge can be wet and sticky or dry and crusty, depending on how much of the liquid in the discharge has evaporated. It is most easily removed with a warm washcloth. 

Source: Eye Physicians of Long Beach

A number of conditions can cause eye discharge (e.g., conjunctivitis), often presenting with additional symptoms (e.g., eye redness, pain, etc). In infants, nasolacrimal duct obstruction (NLDO) or dacryostenosis is the most common disorder of the lacrimal system, often causing a disproportionate amount of rheum and tearing in affected patients; eye redness is uncommon. Spontaneous resolution occurs by 6 months of age in ~90% of infants with congenital NLDO, and two thirds of the remainder have spontaneous resolution by 12 months of age. The cases that persist beyond 12 months of age are likely to require ophthalmologic intervention (i.e., probing of the lacrimal duct). Infants at increased risk for this condition include those with trisomy 21, branchioocculofacial syndrome, CHARGE syndrome, and Goldenhar syndrome.

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