DaxibotulinumtoxinA for Blepharospasm

Inclusion Criteria:

* Adults (18 years of age, or older)
* Clinical diagnosis of Blepharospasm that is disruptive enough to warrant ongoing clinical botulinum toxin injections and scoring ≥2 on the BSRS during screening. Blepharospasm may be focal (i.e. Benign essential blepharospasm), associated with non-drug-induced secondary cause (e.g., typical or atypical parkinsonism) or as part of a diagnosis of segmental or generalized dystonia involving the upper cranial region, if blepharospasm is the only indication requiring botulinum toxin injections.
* Currently receiving onabotulinumtoxinA or incobotulinumtoxinA for the treatment of blepharospasm with: 1) documented duration of benefit \<12 weeks from most recent injection; and 2) no further dose escalation possible or advised due to side effect risk (e.g., ptosis, diplopia, etc.), as determined by treating neurologist; and 3) ability to provide informed consent and comply with study procedures, or subject has a reliable caregiver/proxy.
* Written informed consent including authorization to release health information.

Exclusion Criteria:

* Tardive or medication-induced blepharospasm, as well as psychogenic/functional blepharospasm.
* Active ocular pathology interfering with evaluation or injection safety.
* Neuromuscular junction or motor neuron disorders (e.g., myasthenia gravis, Lambert-Eaton Myasthenic Syndrome, Amyotrophic Lateral Sclerosis, etc.).
* Known hypersensitivity to botulinum toxin or formulation components.
* Pregnant or breastfeeding women (including those who are found to be pregnant after a positive pregnancy test at Screening), women who are hoping to get pregnant over the upcoming 15 months, or women of childbearing potential who are unwilling to use contraception while enrolled in the BLEXI study.
* Any signal suggestive of active suicidality, as per C-SSRS at screening.
* Subjects who have undergone Deep Brain Stimulation (DBS) surgery for the management of blepharospasm and are not willing to keep the DBS settings unchanged for the duration of the trial.
* History of primary or secondary non-response to BoNT-A injections, particularly those known to have neutralizing antibodies to BoNT-A.
* Subjects on oral medications for dystonia (e.g., anticholinergics, muscle relaxants, benzodiazepines, dopamine depleter) who have not been stable on their regimen for at least 4 weeks prior to Screening, or who are not willing to keep them stable for the duration of the trial.
* Use of aminoglycoside antibiotics, polymyxins, lincosamides (e.g., clindamycin), or other agents that might interfere with neuromuscular transmission (e.g., curare-like drugs, quinidine, magnesium sulfate, anticholinesterases, succinylcholine chloride) within 14 days prior to Screening.
* History of severe (stage 3) chronic obstructive pulmonary disease, or unstable pulmonary disease within 30 days prior to Screening.
* History of chronic or recurrent hypokalemia.
* History of congestive heart failure (New York Heart Association Class III or IV), Torsade de Pointe (TdP), and/or Long QT Syndrome.
* Subjects in an investigational drug or device study within the last 30 days prior to Screening.
* Active skin infections at the injection sites which would put the subject at increased risk of morbidity with BoNT injections
* History of blood coagulation disorder that makes facial injection an absolute contraindication
* Any acute illnesses or medical conditions including cognitive impairment (e.g., dementia), significant psychiatric illnesses (e.g., major depressive or bipolar disorder) or symptoms (e.g., suicidal ideation, psychosis) that are not stable, and in the Investigator's opinion, could put the subject at increased risk of morbidity, confound the study results, or interfere significantly with the subject's participation in the study.