Optic Neuropathy

Case example

Glow in the orbit

A 13-year-old, male-castrated mixed breed dog presented for protrusion of left eye and ipsilateral mydriasis.

CT findings

Image Set 1: Focally thickened, left optic nerve sheath creates a well delineated mass, causing a mild mass-effect and rostral deviation of the ocular globe. The mass is mildly heterogeneously and markedly contrast-enhancing.

Image 2: Mildly convex optic disc. The retrobulbar space is normal. There is no evidence of intracranial extension and the included lymph nodes are normal.


  • Primary soft tissue neoplasm of left optic nerve: meningioma, astrocytoma or less likely lymphoma.

Learning points

  • Isolated optic neuritis considered less likely, given reported clinical findings (lack of acute loss of vision), segmental enlargement and mass effect, heterogenous enhancement characteristics and lack of contralateral optic nerve changes.

More information

  • »Ocular Neoplasia in Small Animals«
    — Dubielzig., Vet Clin of North America: Small Animal Practice; 1990; 20(3):837-848
  • »Optic neuritis in dogs: 96 cases (1983-2016)«
    — Smith et al., Veterinary Ophthalmology 2017; 21(5): 442-451
  • »Optic nerve astrocytoma in a dog«
    — Rozov et al., Clinical Case Reports 2016; 4(9): 855-860

Images courtesy of Evidensia Eläinsairaala Tammisto, Finnland.