Transforniceal lateral deep bone decompression--a modified technique to prevent postoperative diplopia in patients with disfiguring exophthalmos due to dysthyroid orbitopathy.

Background/purpose: Postoperative diplopia remains a significant complication of orbital decompression in dysthyroid orbitopathy. This study evaluated the results of orbital decompression treatment using a transforniceal approach to sculpt the lateral orbital deep bone area.
Methods: The two areas of bone in the deep lateral orbit (the basin of the inferior orbital fissure and the sphenoid door jamb) were exposed using a transforniceal swinging eyelid approach. An electric drill was used to sculpt these deep bone areas of the lateral orbit, and approximately 1 mL intraconal fat was removed simultaneously. Between October 1999 and March 2003, transforniceal lateral deep bone decompression was performed in 35 consecutive patients (62 orbits) with disfiguring dysthyroid orbitopathy. Data on proptosis reduction effect, new-onset diplopia and other complications of lateral wall decompression were analyzed.
Results: The average preoperative Hertel value was 21.2 +/- 1.3 mm (range, 18-23 mm) and decreased to 17.4 +/- 1.2 mm (range, 15-19.5 mm) postoperatively. The mean decrease in proptosis 3 months postoperatively was 3.8 +/- 0.91 mm (range, 1.5-4.6 mm). New-onset downgaze diplopia occurred in two (5.7%) of the 35 patients. Persistent trigeminal paresthesia was noted in one patient (2.8%). No cerebrospinal fluid leak, globe injury or vision deterioration was noted during 9.5 +/- 1.7 months of follow-up. The cosmetic appearance was improved in all patients after surgery.
Conclusion: Transforniceal lateral deep bone decompression produces less new-onset, persistent diplopia than traditional inferomedial wall decompression, and provides good cosmesis by using a hidden small incisional wound. This approach appears to be a safe and effective procedure for patients with disfiguring exophthalmos, especially for Asian patients without crease fold.