To evaluate the efficacy of re-recession or extirpation of inferior oblique (IO) muscle in recurrent or undercorrected IO overaction (IOOA).

We reviewed the records of 26 patients (33 eyes) with the recurrent or undercorrected IOOA after the graded recession of IO muscle, who underwent re-recession or extirpation of IO muscle, and was followed up for at least 6 months. We performed extirpation of IO muscle overacting larger than +2 after 14 mm recession of IO muscle or larger than +3 after 10 mm recession of IO muscle. In case of +2 IOOA after 10 or 8 mm recession of IO muscle, we carried out 14 mm re-recession of IO muscle. IOOA under +1 was defined as a successful case after re-operation.

Thirty one of 33 eyes (93.9%) were corrected successfully after re-operation; 24 eyes with extirpation of IO muscle (96.0%) and 7 eyes with 14 mm re-reccession of IO muscle (87.5%) were successful.

One of the advantages of graded recession of IO muscle is that additional re recession or extirpation of IO muscle can be preformed if needed. Extirpation or 14 mm re-recession of IO muscle was effective re operation procedure to correct a recurred or undercorrected IOOA.