Optic nerve sheath infiltration in dysthyroid optic neuropathy

To assess the association of optic nerve sheath (ONS) infiltration, fat infiltration, and scleral enhancement with active thyroid eye disease (TED) and dysthyroid optic neuropathy (DON).

Thyroid eye disease patients who had axial and coronal fat-suppressed contrast enhanced T1-weighted magnetic resonance imaging (MRI) imaging performed were included. Optic nerve sheath infiltration was defined by the presence of thickening and circumferential enhancement of the optic nerve sheath. Clinical assessments were performed by orbital surgeons or neuro-ophthalmologists and the disease activity (active/inactive) and presence or absence of dysthyroid optic neuropathy were recorded.

The study population consisted of 76 orbits from 38 patients with a mean age of 53 ± 15 years, with 25 (66%) being female. Optic nerve sheath infiltration was present in 28 (37%) orbits, fat infiltration in 37 (49%) and scleral enhancement in 14 (18%) orbits. ONS infiltration (OR 19.8, p < 0.01), fat infiltration (OR 5.2, p < 0.01) and scleral enhancement (OR 12.2, p = 0.01) were all significantly associated with active clinical disease. Patients with ONS infiltration had a significantly higher odds of dysthyroid optic neuropathy (OR 3.4, p < 0.05). Fat infiltration (OR 2.8, p = 0.1) and scleral enhancement (OR 2.3, p = 0.23) were not significantly associated with DON.

Optic nerve sheath infiltration may be a predictor of dysthyroid optic neuropathy. Intraorbital fat infiltration and scleral enhancement may be used to detect active TED. These radiological findings may serve as useful diagnostic and stratification tools in evaluating TED patients.