A concept for the surgical treatment of trochlear palsy.

The outstanding clinical symptom of acquired uni- and bilateral trochlear palsy is excyclotropia which increases in down-gaze. Any surgical treatment must aim at reducing this deviation. To achieve this, we have routinely used a modification of the Harada-Ito operation over the last 20 years. The anterior part of the tendon is pulled anteriorly and laterally by a loop of unresorbable suture. This not only increases incyclotorsion but also depression in adduction and reduces the V-pattern. In cases with more than 5 degrees vertical deviation, we performed an additional tuck of the posterior part of the tendon. Our results are compared with those of either superior oblique tuck or combined operations on the oblique muscles published by other authors. They have also used the Harms' tangent screen for quantification of the effect of the operations. In down-gaze, similar results have been obtained but less postoperative Brown's syndrome was found with our modified Harada-Ito procedure. Thus, our modification of the Harada-Ito procedure is an effective and safe approach to the surgical treatment of trochlear palsy with less postoperative limitation of elevation and less torsional overcorrection in up-gaze.