This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Dacrocytorhinostomy involves? 
Select and explain. 
A. Opening up the terminal blocked end of nasolacrimal duct, B. Connecting the lacrimal sac to nose by breaking the medial wall, C. Complete excision of lacrimal, D. Inseion of drainage tube in the lacrimal sac
B: Connecting the lacrimal sac to nose by breaking the medial wall
Answer: B: Connecting the lacrimal sac to nose by breaking the medial wall 
Explanation: Ans. is 'b' i.e., Connecting the lacrimal sac to nose by breaking the medial wall Dacryocystorhinostomy is the surgical procedure which involves removal of bone adjacent to lacrimal sac (medialwall) and incorporating the lacrimal sac with lateral nasal mucosa (at middle meatus) in order to bypass the obstruction in nasolacrimal duct. Advantage of dacryocystorhinostomy over dacryocystectomy is that there is no epiphora or watering of eyes posteoperatively. Indications of dacryocystorhinostomy are :- Congenital or acquired nasolacrimal duct obstruction. Functional obstruction to lacrimal outflow (e.g. lacrimal pump weakness) or facial nerve palsy. History of dacryocystitis Dacryocystorhinostomy can be done either open (external) approach or endonasal (endoscopic) approach.