Misplaced botulinum toxin can cause visual disturbance by affecting the muscles that coordinate eye movement. All three of the neuromodulators that are commonly used and FDA approved for cosmetic use in the US (Botox, Dysport, Xeomin) are extremely safe, when in the right hands. Any horror stories that you hear are likely performed by unlicensed providers at a medi spa, home injection party, dentists office, etc. When put in improper places with incorrect doses, problems can definitely happen. These unqualified injectors, although especially prevalent where I practice, are everywhere across the US. Choose somebody whose entire practice revolves around facial anatomy, facial cosmetics, and who's training was specific to that - this is not your cardiologist or geriatrician who took a few weekend courses. Stay away from the dentist, internal medicine doctor, family practice doctor, etc who decided to inject Botox on the side to make a few extra bucks. You often find the best deals with these unqualified providers or medi spa's, but you will get what you pay for in the end. It is also worth noting that just because somewhere does a lot of Botox does not necessarily mean they are good at it; doing the same thing wrong a thousand times just makes one better at doing it wrong. Scientifically: Botulinum toxin was first isolated in the 20s, was first used therapeutically in 1968, and became approved in 1989 for eye issues. It has been used heavily for cosmetic use since 2002, and it was the first aesthetic drug ever approved. All that is to say...it has a lot of safety data behind it. Recent evidence (coming out this week) proves that botulinum toxin does NOT enter your brain as it's distant cousin tetanus toxin does, which is where that theory came from. Botox, Dysport and Xeomin are the 3 botulinum toxins approved for cosmetic use in the US. They all work in the same way, at the presynaptic terminal blocking the release of acetylcholine - making the nerve temporarily unable to communicate with the muscle. It is broken down as a protein in our body with liver metabolism. Effects are temporary, and repeated use serves to take tension off of your skin, relaxing lines and wrinkles. To ensure you are receiving the highest level of care, seek out a modernly trained, new-school dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these "core four" cosmetic specialties. Membership in organizations like the American Academy of Facial Plastic and Reconstructive Surgery help to identify a highly trained surgeon. Cameron Chesnut #realself500 Physician