Fig. 4 Patient with a left sixth-nerve palsy undergoing left medial rectus muscle injection of botulinum A toxin. A. The eyelids are held open with the index finger and thumb and the patient is directed to look out of the field of action of the injected left medial rectus muscle. B. Once the electrode is inserted through the conjunctiva, the patient is asked to look into the field of action of the injected muscle to increase the electromyographic signal. The needle is advanced until the loudest signal is heard and then the fluid is injected. There is often attenuation of signal with injection.