Transorbital Sonography and Visual Outcome for the Diagnosis and Monitoring of Optic Neuritis

Background and purpose: Transorbital sonography (TOS) is a promising tool to support the clinical diagnosis of optic neuritis (ON) by showing thickening of optic nerve. In this study, we aimed to define its specific role in follow-up of ON patients.

Methods: We measured ultrasonography parameters and visual acuity (VA) at presentation and after 1 year in 45 patients with newly diagnosed ON. Two vascular sonographers used B-mode TOS to evaluate mean optic nerve diameter (OND) and optic nerve sheath diameter (ONSD).

Results: Median ONSD values were significantly thicker in patients with ON in the affected eye (6.4 mm, interquartile range [IQR]: 6.0-6.9) at presentation compared with the nonaffected side (5.7 mm; IQR: 5.2-6.1) (P < .001). The median OND was not significantly thicker at presentation in the affected eye (3.0 mm; IQR: 2.9-3.4) compared with the fellow eye (2.9 mm; IQR: 2.8-3.2) (P = .09). Logarithmic VA was significantly compromised at presentation in the affected eye (.16; IQR: .00-.55) compared with fellow eye (.00; IQR: .00-.00) (P < .001). After 1 year, no significant difference (P ≥ .05) was found between ONSD or OND of the affected side compared with the nonaffected side. VA improved in most of the patients but remained significantly impaired in affected eye after 1 year.

Conclusions: TOS is a useful tool to support diagnosis of ON. This technique seems to have less value to evaluate atrophy of the optic nerve after 12 months.