Traumatic optic neuropathy

Background

• Acute injury to the optic nerve from direct or indirect trauma resulting in vision loss
• Caused by indirect injury to the optic nerve (intracanalicular portion) from transmitted shock from an orbital impact
• Can also be caused by directly by penetrating injury or from bony fragments in the optic canal or orbit, or orbital hemorrhage and optic nerve sheath hematoma

Pathophysiology

• Indirect: Hypothesized to result from shearing injury to the intracanalicular portion of optic nerve, which can cause axonal injury or disturb the blood supply of the optic nerve
• Direct: Presumed to be the result of tissue disruption secondary to foreign body or bony fragments impacting the optic nerve

Clinical Features

History

• Acute unilateral vision loss, decreased color sensation, and/or visual field deficit after blunt or penetrating trauma
• Complaints may be delayed due to the impact of and treatment for other concomitant head injuries

Physical Exam

• External eye exam may show signs of orbital trauma or fracture (soft tissue edema, hematoma, step-off on palpation of orbital rim)
• Decreased visual acuity and an afferent pupillary defect (in unilateral cases)
• On funduscopy, the initial optic nerve head assessment will be normal; optic atrophy may be seen 3-6 weeks after trauma

Differential Diagnosis

• Posterior ischemic optic neuropathy
• Optic neuritis
• Optic nerve avulsion
• Non-organic vision loss
• Pre-/intra-/subretinal hemorrhage
• Choroidal rupture
• Commotio retinae
• Traumatic iritis

Acute Vision Loss (Noninflamed)

• Arteritic anterior ischemic optic neuropathy
• Amaurosis fugax
• Central retinal artery occlusion (CRAO)^†
• Central retinal vein occlusion (CRVO)^†
• High altitude retinopathy
• Open-angle glaucoma
• Optic neuritis
• Posterior Reversible Encephalopathy Syndrome (PRES)
• Retinal detachment^†
• Temporal arteritis^†
• Traumatic optic neuropathy
• Vitreous hemorrhage
• Stroke^†

^†Emergent Diagnosis

Orbital trauma

Acute

• Ruptured Globe^
• Corneal Abrasion
• Ocular foreign body
• Conjunctival laceration
• Caustic Keratoconjunctivitis^^
• Subconjunctival hemorrhage
• Traumatic iritis
• Traumatic hyphema
• Retinal detachment
• Retrobulbar hemorrhage/hematoma
• Traumatic mydriasis
• Orbital fracture
  • Frontal sinus fracture
  • Naso-ethmoid fracture
  • Inferior orbial wall fracture
  • Medial orbital wall fracture

Subacute/Delayed

• Endophthalmitis^
• Corneal Ulcer^

Evaluation

Workup

• Non-contrast CT of head and face (including orbits)

Diagnosis

• Primarily a clinical diagnosis

Management

• Ophthalmology consult
  • Generally, no acute interventions are known to change prognosis

Contraindicated

• Corticosteroids not helpful
• Surgical intervention has not shown to be beneficial, although some support the use of surgery in certain scenarios (e.g. bony fragment abutting optic nerve or optic nerve sheath hematoma)

Disposition

• Outpatient ophthalmology follow up

Prognosis

• Visual improvement in only about 50% of patients

External Links

• http://eyewiki.aao.org/Traumatic_Optic_Neuropathy

References

Authors

Ross Donaldson, Michael O'Brien, MD