[Effects of external orbital radiotherapy on the oculomotor muscle in Graves disease].

PURPOSE

Orbital radiotherapy is recognised to be effective in the treatment of acute Graves' disease. The effect on the oculomotor muscles is still controversial.

MATERIAL AND METHODS

To assess this effect, we conducted a prospective study on 15 patients with acute Graves' ophthalmopathy. Patients were investigated before radiotherapy, 3 months later and at long term (mean = 2 years). To study the extent of the ophthalmopathy we chose the following criteria: class IV in the NOSPECS classification system, amplitude of gaze, measurement of the thickness of oculomotor muscles (CT-scan).

RESULTS

Improvement of the amplitude of gaze and reduction of the thickness of oculomotor muscles were not statistically significant. The oculomotor disorder was unchanged 3 months after radiotherapy. After a long term follow up (mean: 2 years), only 5 patients, among those who complained of diplopia before radiotherapy, had to be operated, especially large deviations.

CONCLUSION

Orbital radiotherapy does not appear as a direct treatment for oculomotor disorder in active thyroid related ophthalmopathy, however favorable indirect effects may be effective due to reduction of inflammation. As it is a harmless treatment, orbital radiotherapy may be proposed as primary treatment in active thyroid related ophthalmopathy.