Surgical exploration in persistent inferior oblique overactions

To report the causes of persistent inferior oblique (IO) overactions after disinsertion procedure.

Surgical findings of nine eyes of eight patients who needed secondary surgery to the IO muscles because of persistent overaction after IO disinsertion were evaluated retrospectively. Inferior obliques were found partially retracted into their sheath, and some parts of the proximal muscle stumps were found to have established attachments through scar tissues to the sclera in five eyes. They were totally in the subtenon space, reattached to the sclera in the three eyes and were found untouched; inferior rectus was disinserted instead of IO muscle, in the last eye. Proximal terminals of the IOs were isolated, dissected from its sheath and from other fascial attachments. The muscle stump pushed out of subtenon's space through its Tenon's sheath after 5-8 mm myectomy and cauterization to prevent any direct or indirect contact between the muscle and sclera.

Persistent overactions of IO muscles were resolved in all cases and did not return in any case in the follow-up period of 4 months to 6 years.

Persistent overaction of IO muscle after disinsertion usually results from insufficient retraction of the muscle from the subtenon's space. It can be both prevented and managed by complete dissection of the IO muscle from its all fascial attachments and pushing the proximal terminal of the muscle completely out of subtenon's space through its sheath traversing Tenon's capsule after a segment myectomy and cauterization.