Extracranial orbital decompression for optic neuropathy in Graves' eye disease.

Optic neuropathy affects a small proportion of patients with Graves' eye disease. It is due to optic nerve compression by enlarged extraocular muscles and can be treated by corticosteroids, irradiation or surgical orbital decompression. The current report evaluates the effectiveness of extracranial orbital decompression performed by one surgeon for optic neuropathy in Graves' eye disease. The records of 21 patients (33 orbits) undergoing extracranial orbital decompression for Graves' optic neuropathy were analysed for changes in visual acuity and colour vision and reduction in proptosis. Visual acuity and colour vision improved in all 33 eyes in the short-term postoperatively (4 weeks), but later deteriorated in 5 eyes (6.6%) of 4 patients (19%). The remainder maintained improved vision for the duration of the follow-up period (mean 22, range 3-54 months). Proptosis decreased by a mean 5.0 mm (range 1-8). Extraocular muscle imbalance and diplopia worsened in 9 21 patients (43%) and improved in 2 21 (9.5%). The patients having medial wall and floor decompressed all had worse diplopia (5 5 ), those with medial and lateral wall worsened in 4 10 cases and improved in 1 10 , and those having all three walls decompressed had no cases of worsening diplopia and 1 6 improved. All patients with symptomatic diplopia achieved binocular single vision in a useful range after one and sometimes two squint procedures. No patient lost vision as a result of the extracranial orbital decompression, but one lost vision in one eye after transfrontal decompression following failed extracranial decompression. Extracranial orbital decompression is effective in improving vision and reducing proptosis in most patients with optic neuropathy in Graves' eye disease, but induces or worsens diplopia in a high proportion of patients. The diplopia is readily correctable, and the change to decompressions that include the lateral wall may reduce the risk of postoperative diplopia.