Are we overlooking masked bilateral congenital superior oblique palsy in children: is it possible to diagnose before surgery?

PURPOSE

To describe the characteristics of children who had subsequent contralateral superior oblique underaction (SOUA) and inferior oblique overaction (IOOA) after unilateral inferior oblique weakening surgery and to identify suggestive clinical features for masked bilateral fourth nerve palsy.

METHODS

The medical records of children who underwent unilateral inferior oblique tenotomy as a single procedure for unilateral superior oblique palsy were all reviewed. Diagnosis was based on evaluation of ocular misalignment in nine diagnostic gaze positions and presence of SOUA, IOOA, and abnormal head position.

RESULTS

The study was conducted with 29 children. All children had preoperative unilateral IOOA and SOUA. Eleven children (37.9%) had hyperesodeviation in the affected eye, while others (62.1%) had hyperexodeviation. The mean age at surgery was 6.66 ± 1.87 (4-10) years. The mean vertical deviation, exodeviation, and the amount of IOOA were decreased postoperatively (p < 0.001 for all). Among the 29 children, 22 had no residual ipsilateral IOOA, 2 had ipsilateral IOOA, and 5 had ipsilateral inferior oblique underaction (IOUA) at last visit. Three children had contralateral SOUA, IOOA, and hyperdeviation at follow-up visits, one of whom had IOUA on the operated eye. There was no difference of preoperative features between children with or without subsequent contralateral superior oblique palsy.

CONCLUSION

Bilateral congenital superior oblique palsy may be overlooked in children in spite of detailed preoperative evaluation. Masked bilaterality should always be kept in mind in cases with unilateral pathology. Patients should be informed about the possibility of bilaterality.