Augmented endoscopic orbital apex decompression in dysthyroid optic neuropathy

Abstract

Purpose: To describe a modified technique of endoscopic orbital decompression for dysthyroid optic neuropathy nonresponsive to pulsed corticosteroids.

Methods: Retrospective, interventional single centre case series included 17 consecutive patients with dysthyroid optic neuropathy (DON) who were refractory to pulse corticosteroids. Removal of the posteromedial floor and the orbital process of palatine bone (OPPB) was performed in addition to the endoscopic transethmoidal medial orbital wall decompression (ETMOWD), to achieve maximal orbital apex decompression. Main outcome measures were change in visual acuity (VA), color vision, degree of proptosis reduction, incidence of new-onset diplopia, and any complications.

Results: Seventeen eyes (100%) had a statistically significant improvement in VA from 1.0 ± 0.44 LogMAR to 0.0 ± 0.15, with an average improvement of 0.41 ± 0.30 LogMAR (p 0.05, paired t-test). Fourteen out of 16 eyes had a complete improvement in color vision and two eyes had partial recovery. Afferent pupillary defect (76.5%) resolved in all cases. Five out of 10 cases with preoperative visual field defects demonstrated no residual field defects following surgery. The range of proptosis reduction was 0-5 mm (mean 2.7 ± 1.3 mm). No patients with diplopia (12/17) had worsening or developed new-onset diplopia following surgery.

Conclusion: Combined removal of the posterior medial floor including the OPPB with ETMOWD may be a viable alternative in the surgical management of DON.

Fig. 1

Endoscopic view of the orbital apex of skull model highlights the removed areas with dashed lines—minor wing of sphenoid (yellow, near optic foramen), the orbital process of palatine bone (red triangle), and the lateral portion of posterosuperior aspect of posterior maxillary sinus wall (pink).

Fig. 2

Transilluminated orbital floor and medial orbital wall show the thick areas in the orbital apex represented by OPPB (bold arrow) and MWS (smaller arrow); M medial orbital wall; L lateral orbital wall; F floor of the orbit

Fig. 3

Intraoperative endoscopic view showing the decompressed orbital apex (white curvilinear line) with drilled OPPB (marked with an arrow), the exposed periorbita along the medial wall (marked with an asterisk) and the opened up sphenoid sinus (marked with a small asterisk)