Nocturnal lagophthalmos

Evaporative loss can also occnr from abnormal ocular surfece exposure, due to incomplete blink, nocturnal lagophthalmos, exophthalmos, proptosis, cranial nerve VII palsy, lid retraction, or other eyelid position and apposition disorders. Contact lenses may also contribute to an increased tear evaporation rate. 

There are many other causes of RCE, but they occur much less frequently. Among these causes are chemical or thermal burns, herpes simplex keratitis, neuroparalytic keratitis, bullous keratopathy, severe dry eyes, nocturnal lagophthalmos, diabetes mellitus, meibomian gland dysfunction, ocular rosacea, and Alport syndrome. Approximately 5% to 30% of RCEs occur spontaneously without any known predisposing fector. 

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