In oculomotor surgery, evaluation of muscle elongation is necessary be
fore deciding on the operative plan. This is particulary important in
recurrent esotropia where the motor problem is highly complex because
of visco-elastic alterations caused by previous surgery. The study of
a series of 132 cases of recurrent esotropia shows that weakening of t
he medial rectus almost always causes reduced muscle elongation, the e
xtent of which is directly proportional to the amount of recession.