A prevalent concept in strabismus surgery is that excessive recessions cripple an extraocular muscle because of a decrease in mechanical advantage. The mathematical analysis presented, coupled with length-tension diagrams, supports my hypothesis that gross underactions of muscles excessively recessed are due primarily to a marked decrease in the force of contraction rather than a marked loss in mechanical advantage.
Beisner DH. Reduction of Ocular Torque by Medial Rectus Recession. Arch Ophthalmol. 1971;85(1):13-17. doi:10.1001/archopht.1971.00990050015003