Botulinum toxin injection and tear production.

[PURPOSE OF REVIEW] In 1980, botulinum toxin type A (BTX-A) was introduced for the treatment of strabismus and benign essential blepharospasm. Since then, a number of additional indications have been introduced, which continue to expand, providing less invasive solutions in managing different ophthalmic conditions.

[RECENT FINDINGS] Successful trials of BTX-A injection into the lacrimal gland have been reported for the treatment of epiphora caused by primary lacrimal gland hyperlacrimation, functional tearing, gustatory tearing, and lacrimal outflow obstruction. This is achieved through blockage of the cholinergic receptors by BTX-A at the glandular level. Interestingly, BTX-A has also been found to be useful in treating patients with dry eyes by compromising the tear drainage from the eye through injection of BTX-A in the medial part of the lower eyelid. BTX-A may help provide effective relief for patients who have two different ophthalmic comorbidities such as benign essential blepharospasm and dry eye.

[SUMMARY] Better understanding of the mechanism of BTX-A action in the treatment of the growing applications in ophthalmology helps provide relatively noninvasive solutions for patients. Full awareness of possible side effects of BTX-A and the optimal way to manage them is vital for the success of this treatment option.