Lagophthalmos is incomplete closure of the eye. There are several types of lagophthalmos all of which can cause or contribute to symptoms of Dry Eye.
Blink lagophthalmos
Blink lagophthalmos describes incomplete closing of the eye during a blink. Blinking is important because it spreads tear film across the eye surface and is part of the mechanism that causes meibum secretion. When blinks are incomplete, the tear film is not spread properly over the eye surface which may lead to dry spots and Dry Eye symptoms. Many conditions can cause or contribute to incomplete blinks including: performing work that requires focus, such as reading, or driving; having eye lashes that collide.
Iatrogenic lagophthalmos
Iatrogenic conditions are conditions caused by medical treatment. Iatrogenic lagophthalmos describes incomplete eye closure caused by a medical treatment such as Botox injections.
Nocturnal lagophthalmos
Nocturnal lagophthalmos happens while sleeping and is often an overlooked cause of Dry Eye symptoms. Nocturnal lagophthalmos can occur if the fatty tissue behind the eye deteriorates. When this happens, the eye ball falls further back into the socket and the eye may not close completely when sleeping. The fatty tissue behind the eye may deteriorate for a number of reasons including: autoimmune disease such as Hashimoto’s hypothyroidism.
Paralytic lagophthalmos
Paralytic lagophthalmos is a condition in which paralysis of the seventh cranial nerve prevents the eye from closing completely. Paralysis may be due to Bell’s palsy, injury, tumors, or other trauma. Ectropian is a common comorbidity.
Reference
Lagophthalmos
Pereira MV, Glória AL.
Seminars in ophthalmology
2010 May;25(3):72-8. doi: 10.3109/08820538.2010.488578.
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