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 fundoscopy, 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)

• Painful
  • Arteritic anterior ischemic optic neuropathy
  • Optic neuritis
  • Temporal arteritis^†
• Painless
  • Amaurosis fugax
  • Central retinal artery occlusion (CRAO)^†
  • Central retinal vein occlusion (CRVO)^†
  • High altitude retinopathy
  • Open-angle glaucoma
  • Posterior reversible encephalopathy syndrome (PRES)
  • Retinal detachment^†
  • Stroke^†
  • Vitreous hemorrhage
  • Traumatic optic neuropathy (although may have pain from the trauma)

^†Emergent Diagnosis

Orbital trauma

Acute

• Caustic keratoconjunctivitis^^
• Conjunctival hemorrhage
• Conjunctival laceration
• Corneal abrasion, Corneal laceration
• Globe rupture^
• Iridodialysis
• Lens dislocation
• Ocular foreign body
• Orbital fracture
  • Frontal sinus fracture
  • Naso-ethmoid fracture
  • Inferior orbial wall fracture
  • Medial orbital wall fracture
• Posterior vitreous detachment
• Retinal detachment
• Retrobulbar hemorrhage/hematoma
  • Ocular compartment syndrome
• Subconjunctival hemorrhage
• Traumatic hyphema
• Traumatic iritis
• Traumatic mydriasis
• Traumatic optic neuropathy
• Vitreous detachment
• Vitreous hemorrhage
• Ultraviolet keratitis

Subacute/Delayed

• Corneal ulcer^
• Endophthalmitis^

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