Dysthyroid Optic Neuropathy Dramatically Improved by Sheath-Guided Triamcinolone Orbital Injection: A Case Report

Thyroid eye disease is an autoimmune disorder caused by thyroid-stimulating hormone receptor autoantibodies stimulating the thyroid-stimulating hormone receptor, resulting in proptosis, extraocular muscle dysfunction, diplopia, retro-orbital pain, optic nerve compression, and visual impairment. Dysthyroid optic neuropathy (DON), believed to result from direct compression by enlarged extraocular muscles, represents a severe complication with the potential for irreversible vision loss. Currently, the treatment options for DON are limited to highly invasive procedures, such as orbital decompression surgery and systemic steroid pulse therapy. There are consequently significant challenges in the management of this condition. This report presents a case where a significant improvement in DON was achieved solely through the novel technique of sheath-guided orbital triamcinolone injection, which was utilized with the aim of reaching the deeper part of the orbit under sheath guidance. In this case, the best corrected visual acuity improved from 20/32 (decimal visual acuity: 0.7) to 20/20 (1.2) in the right eye and from 20/500 (0.04) to 20/20 (1.2) in the left eye. Critical flicker frequency values also improved, from 20.3 Hz to 35.0 Hz in the right eye and from 9.3 Hz to 31.5 Hz in the left eye. The cross-sectional areas of the extraocular muscles decreased by an average of 55.5%.