Radiotherapy for thyroid orbitopathy. Effects on extraocular muscle balance.

OBJECTIVE

To investigate the effects of radiotherapy on the restrictive ophthalmopathy and strabismus that occur with Graves' orbitopathy.

DESIGN

A prospective study of patients with motility disturbances due to thyroid orbitopathy, followed by serial quantitative measurements of ocular restrictions and deviations, both before and at 1 and 6 months after treatment with high-energy radiotherapy.

SETTING

Urban subspecialty private practice.

PATIENTS

Thirty-three consecutive patients with restricted extraocular movements and diplopia secondary to thyroid orbitopathy who were treated with radiotherapy were seen during an 8-year period.

MEASURES

Maximal horizontal and vertical ductions, plus ocular deviations in primary and reading positions of gaze, were quantitatively evaluated by one clinical investigator to ensure consistency.

RESULTS

Statistically significant improvement in gaze restriction on supraduction and improvement of vertical and horizontal strabismus were demonstrated at follow-up visits after treatment.

CONCLUSIONS

Although statistically significant improvement of motility disturbances were demonstrated after radiotherapy, there was less than desirable functional improvement of restrictive ophthalmopathy and strabismus; thus the usefulness of radiotherapy was limited when it was used alone to treat diplopia.