In a technique pioneered by Alan B. Scott, an ophthalmologist, and Edward Schantz, a biochemist, in the late 1970s, botulin toxin has been purified and used in the treatment of debilitating muscle spasms caused by the excessive firing of certain nerves. The treatment utilizes the same process that paralyzes the muscles in botulism poisoning. Injected in tiny amounts into the affected tissue, the botulin blocks the release of acetylcholine, a neurotransmitter that controls muscle contraction, and temporarily relieves the spasms. Botulin was approved by the Food and Drug Administration in 1989 for treatment of blepharospasm (uncontrolled rapid blinking) and strabismus (crossed eyes). The toxin is also injected to treat other conditions, such as neck muscle spasms, and to provide short-term (three to four months) cosmetic treatment of facial wrinkles.