Long-term visual outcome following orbital decompression for dysthyroid eye disease.

The records of 33 patients who had undergone inferior and medial wall orbital decompressions for compressive optic neuropathy due to dysthyroid eye disease were reviewed. The indication for surgery in 32 patients was a reduction in Snellen visual acuity. The remaining patient had bilateral optic disc swelling but normal visual acuity. Twenty-nine patients (88%) were treated with systemic steroids pre-operatively, which resulted in an improvement in vision in all cases. In the immediate post-operative period visual acuity either improved or the steroid-induced visual improvement was maintained as the steroids were tailed off. Long-term visual outcome, however, varied. In 19 patients (58%) visual acuity was maintained with no requirement for additional treatment. In 12 patients (36%) there was a subsequent deterioration in vision which responded to additional treatment with either systemic steroids, orbital radiotherapy or further orbital surgery. In 2 patients (6%) vision continued to deteriorate despite further treatment. We conclude that although orbital decompression has resulted in the long-term preservation of visual acuity in 94% of our patients, there remains a small subgroup (6%) in whom visual function continues to deteriorate despite all forms of treatment.