This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro-ophthalmology, Subject name: Ophthalmology
Epiphora and lagophthalmos following VII nerve injury is due to 
Select and explain. 
A. Failure of lacrimal pump, B. Increased lacrimal secretion, C. Nasolacrimal duct obstruction, D. None of the above
A: Failure of lacrimal pump
Answer: A: Failure of lacrimal pump 
Explanation: (Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 390) *Symptomatic epiphora following facial paralysis is most often associated with one or more of the following: Impairment of eyelid closure A compromised lacrimal pump Lower lid laxity True epiphora is secondary to either an anatomical obstruction of the lacrimal drainage system or functional deficiency like ectropion or lacrimal pump failure. If the punctum is visible without touching the lid, ectropion is diagnosed The main cause for paralytic lagophthalmos is Bell's palsy but it may be secondary to trauma, infections, tumors, and many other conditions. The main purpose when treating lagophthalmos is to prevent exposure keratitis and reestablish eyelid function.