Determination of the Optimum Delivery Route for Botulinum Toxin A in Patients With Epiphora

Epiphora or excessive tearing is a significant disability for many affected patients diminishing their quality of life. There is a growing consensus that injection of Botulinum Toxin A (BTX-A) into the lacrimal gland provides relief in patients with hyperlacrimation secondary to aberrant regeneration of the 7th nerve, and limited evidence that it might help to reduce normal tear production in patients with epiphora from anatomic or functional outflow obstructions. BTX-A has been injected both transconjunctivally into the palpebral lobe of the lacrimal gland and transcutaneously into the orbital lobe. Both delivery routes have been successful in symptom relief with minimal complications. However, the effectiveness of transconjunctival versus transcutaneous injections has not been systematically compared. Also, whether the incidence of side effects is related to the dosage, concentration, or location of injection is unknown and has also not been systematically studied. The investigators plan to conduct a randomized clinical trial in patients with functional tearing comparing the transcutaneous delivery route of BTX-A to the transconjunctival delivery route (the most common route described in the literature). The investigators will also compare the side effect profile of each delivery route.