[Operative procedures in cases of disinserted or missing superior oblique muscles]

If the surgeon cannot find the tendon of the superior oblique muscle in the right place, he has to change his operative plans intraoperatively. Different procedures are recommended: reinsertion of the superior oblique in the right place, recession of the inferior oblique muscle, and operations on the vertical muscles of the same or the yoke eye. No quantitative recommendations on the surgical amount are mentioned in the literature.

Ten patients with different forms of aberrant tendons are presented, four patients with bilateral inferior oblique overaction and superior oblique underaction, and six patients with unilateral strabismus sursoadductorius. The pre-, intra- and postoperative findings are demonstrated.

In cases of mild disinsertions (Helveston classes 1 and 2) the superior oblique tendon was shortened using the normal amount in one or two muscle procedures. If the superior tendon did not reach the sclera (Helveston classes 3 and 4), an operation on the superior oblique alone had not sufficiently corrected the long-term deviations. In cases where both oblique muscles are being operated on, the immediate postoperative effect was slight overcorrection, but the long-lasting effect was good. In only one case did the inferior oblique have to be reinserted in its original place because of long-lasting overcorrection of cyclotropia after the two-muscle procedure.

An "absent" superior oblique tendon can often be found in the superior nasal part of the orbit near the superior rectus muscle. Reinsertion of the tendon in its physiological place (crossing over the superior rectus muscle) will correct smaller amounts of vertical deviation in adduction only. If the vertical deviation exceeds 12 degrees in adduction, the operation on both oblique muscles can always ameliorate the ocular motility. Only in rare cases can a second operation become necessary.