Usefulness of B-scan ocular ultrasound images for diagnosis of optic perineuritis

PURPOSE: This study was performed to examine the usefulness of B-scan ocular ultrasound images for the diagnosis of optic perineuritis. OBSERVATIONS: A 72-year-old woman developed nonpainful blurred vision in her left eye. At the first ophthalmological consultation, she had optic disc swelling and choroidal folds in both eyes and subretinal fluid in the left eye. She was referred to our clinic 1 month after symptom onset. At the first visit to our clinic, she still complained of blurred vision. She was found to have mild vitreous cells in the left eye and optic disc swelling in both eyes. However, the choroidal folds had already resolved in both eyes. B-scan ultrasound images displayed the optic nerve sheath as a highly reflective circle with shadowing around the optic disc in both eyes and scleral thickening in the left eye with fluid in sub-Tenon's space. Bilateral optic perineuritis with posterior scleritis seemed highly plausible. Magnetic resonance imaging with intravenous contrast revealed increased signal intensity around the optic nerve (i.e., the “tram track sign”) in both eyes, which was consistent with optic perineuritis. CONCLUSION AND IMPORTANCE: Optic perineuritis is a rare inflammatory disorder involving the optic nerve sheath. Although magnetic resonance imaging is reportedly useful for diagnosis of this disease, no previous reports have described B-scan ultrasound imaging for this purpose. We herein provide the first report of a patient suspected to have optic perineuritis based on B-scan images. B-scan ultrasound may be useful for diagnosis of optic perineuritis, especially with inflammation surrounding the optic nerve.