Transorbital ultrasonography in acute optic neuritis: Can it be a supportive diagnostic tool?

Because of limitations of conventional tools for diagnosing optic neuritis (ON), transorbital ultrasonography (TOUS) was introduced as a promising tool to evaluate the optic nerve. However, studies demonstrating its utility are scarce.

To assess the practical diagnostic value of TOUS in patients with ON along with other diagnostic tools such as visual evoked potential (VEP), MRI, and optical coherence tomography (OCT).

Seventeen patients with first-attack unilateral acute ON were enrolled. Clinical characteristics, visual acuity, TOUS, MRI, VEP, and OCT results were evaluated. Bilateral optic nerves were scanned using TOUS to obtain axial images showing the optic nerve and the disc in the longitudinal plane.

TOUS revealed thickening of the optic nerve sheath and optic nerve diameter with sheath on the affected side compared with the unaffected side (p = 0.002 and p = 0.003, respectively). Time since onset of initial symptoms was inversely correlated with optic nerve diameter (ρ = -0.517, p = 0.040) and retinal nerve fiber layer thickness (ρ = -0.831, p < 0.001).

TOUS could be a cost-effective tool for morphologically evaluating acute ON showing a significant thickening of the optic nerve and sheath, although only a limited retrobulbar area could be explored.