[Passive length-tension curves of extraocular muscles after botulinum toxin injection].

Botulinum A toxin was injected into the superior rectus muscles of albino rabbits. Length-tension curves of detached superior rectus muscles were continuously measured with a length and tension measuring device developed by the author. The device consists of a strain gauge for measuring passive length-tension, and a position encoder equipped with an eddy current motor. The passive load of the muscle injected with Botulinum A toxin was significantly less than that of control muscle a week after the injection, however, it was greater than that of control muscle in 2 or 3 weeks after the injection. The compliance of the treated muscle was significantly less than that of control muscle at 3 weeks after the injection.