Flower
I am so sorry you are experiencing dry eye symptoms following cosmetic BOTOX service. Are the dry eye symptoms related to your BOTOX treatment even though your doctor states that he has never head of this happening? The answer is of course.
First, let me remind you and other readers of what is stated in the information to physicians that Allergan, Inc, the maker of BOTOX includes in their FDA approved package insert. The first paragraph is the black box warning:
Distant Spread of Toxin Effect
Postmarketing reports indicate that the effects of BOTOX® Cosmetic and all botulinum toxin products may spread from the area of injection to produce symptoms consistent with botulinum toxin effects. These may include asthenia, generalized muscle weakness, diplopia, blurred vision, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence, and breathing difficulties. These symptoms have been reported hours to weeks after injection. Swallowing and breathing difficulties can be life threatening and there have been reports of death. The risk of symptoms is probably greatest in children treated for spasticity but symptoms can also occur in adults treated for spasticity and other conditions, particularly in those patients who have underlying conditions that would predispose them to these symptoms. In unapproved uses, including spasticity in children and adults, and in approved indications, cases of spread of effect have occurred at doses comparable to those used to treat cervical dystonia and at lower doses.
In addition to this warning the insert also describes a number of the more common effects. One of those effects will be local weakness of muscles due to the spreading effects of BOTOX. Pain after treatment and eye fatigue are also reported (less than 1%). When the BOTOX causes weakness of the orbicularis oculi muscle that is responsible for eye closure, there can be some mild weakness of the blink. If you are already predisposed to dry eye, this can make eye dryness symptomatic which is likely what you are experiencing. The fact that your doctor has not previously seen this does not mean that you are not experiencing the problem. Theoretically BOTOX could also block tear production and it is actually used for a treatment of what is called crocodile tears which occurs in unusual clinical situations. So either speeding effects or distant effects of BOTOX can easily explain your symptoms.
I would recommend that you see a cornea specialist, an oculoplastic specialist or your general ophthalmologist for an assessment and treatment advice regarding your dry eye symptoms. These effects will wear off. Should you have the BOTOX treatment again? I think it is possible that you could have BOTOX in the future but you man need to be prepared to use artificial tears for a period of time afterward. I think much will rest on how long these symptoms persist and what is required to make you feel better.