Lagophthalmos is when the eyelids do not close completely, allowing exposure of the cornea. This can lead to irritation, burning, foreign body sensation, eye pain, redness, blurry vision or even reflex tearing. If the cornea becomes eroded from the exposure over a period of time, permanent scaring of the cornea and vision loss can develop. A common cause of lagophthalmos is cranial nerve VII palsy. This nerve controls facial expression, including raising the eyebrows, raising the angle of the mouth and closing the eye. Another common cause of lagophthalmos is thyroid eye disease. Lagophthalmos can develop after eyelid surgery if too much skin has been removed or significant scar contraction of the eyelid occurs. Depending on the cause and chronicity of the lagophthalmos, different procedures can be performed to help bridge the gap when patients close their eyes.