Understanding and Treating Traumatic Brain Injury (TBI) Associated Photophobia With Botulinum Toxin Type A (BoNT-A)

Inclusion Criteria: * Recruit and enroll male and female subjects, civilians and veterans (1:1 mix anticipated, i.e., n = 25 from each group) of all races and ethnicities. * ≥18 years of age who are able to consent. * Report chronic photophobia (Numerical Rating Scale ≥4 on a 0-10 scale, photophobia present ≥6 months) with a remote history of TBI (\>1 year). * Inclusion into the study with regard to TBI status will be based on the Department of Defense Standard Surveillance Case Definition for TBI Adapted for Armed Forces Health Surveillance Division (AFHSB) Use. This can include one hospitalization or outpatient medical encounter with documented International Classification of Diseases (ICD9/ICD10) codes as identified within the Surveillance Case Definition. * Subjects must also have been on a stable medication regimen for the past 3 months and must be naïve to BoNT-A treatment for orofacial conditions. * English as primary language (by self-report). Exclusion Criteria: * Individuals with ocular diseases that may confound photophobia, such as glaucoma, corneal and conjunctival scarring, corneal edema, uveitis, iris transillumination defects, retinal degeneration, etc. * Patients who are participating in another study with an investigational drug within one month prior to screening. * Pregnant individuals. Pregnant subjects will not be scanned in the functional Magnetic Resonance Imaging (fMRI). Although there are no known risks associated with MRI during pregnancy, according to facility policy, University of Miami will not scan someone that is pregnant. Therefore, all women of childbearing potential (menstruating or \>12 years old) must complete a for stating that are not pregnant within 24 hours of each MRI scan. * Individuals with contraindications to fMRI scanning (e.g. metal implants, pacemaker) will not be offered inclusion.