Traumatic optic nerve damage after craniofacial injury was first described by Hippocrates.1 Although the natural history of traumatic optic neuropathy is unknown, recent studies suggest that high dose steroids and, even surgical decompression of the optic canal or the nerve sheath (in cases of nerve sheath hematoma) may restore vision in selected patients.2-8 The commonest cause of optic nerve trauma is road-traffic accidents, when the patient has poly-trauma with head injury and the visual loss is noticed only after the general condition of the patient improves. Isolated trauma of the optic nerve is usually associated with blunt skull trauma involving fractures of both skull and optical canal, but may also occur from blunt ocular trauma.9 Iatrogenic trauma to the optic nerve is not unknown.
Pathophysiology
The part of the optic nerve most vulnerable to blunt trauma of the head is the intracanalicular segment, which by virtue of its bony course is vulnerable to the fractures and compressive-elastic forces of its surrounding bone, which also being unyielding, allows for no space for inflammatory expansion or hemorrhage.10 Optic neuropathy following accidental trauma usually results from two distinct mechanisms: A primary injury as a result of a direct contusive force on the optic canal and nerve, which if untreated results in a secondary ischemia with further damage to the nerve.
Investigations
Clinical assessment should include testing of visual acuity, extraocular muscle motility and papillary reactivity, visual field assessment and direct/indirect ophthalmoscopy. Visual evoked potentials (VEPs) to flash stimulation and the electroretinogram (ERG) might be supportive in unresponsive patients in the immediate aftermath of the traumatic event.11,12 The role of neuroimaging remains controversial, and practice varies between institutions. Recently, ultrasonography has been advocated to screen and detect abnormalities in optic nerve diameter.
Management
Currently, there is no validated approach to the management of traumatic optic neuropathy. Thus, with numerous conflicting reports on the management of traumatic optic neuropathy, there is little world consensus on the optimal management of this condition. Keeping in mind the above, we have devised a management protocol for the same, simultaneously discussing the role of conservative/medical management as well as the surgical protocols followed by us.
Discussion and conclusion
In summary, optic nerve decompression alone or combined with decompression of the nerve sheath may be indicated in selected patients who fail to respond to high-dose intravenous steroids. The definitive role of surgery in the management of traumatic optic neuropathy remains unclear. There is a need for a large, prospective, randomized controlled trial to assess the different therapeutic approaches in traumatic optic neuropathy, but such a trial may be challenging given the low frequency of the condition and the difficulties inherent in randomizing patients.
Spontaneous visual recovery after traumatic optic neuropathy after blunt head injury. Am J Ophthalmol 1990;109:430–35.
Contusion of the optic nerve after minor blunt ocular trauma: Case report and literature review. Opthalmologe 1999;96(8): 529–33.
Traumatic optic neuropathy. Our experience. Indian J Otolaryngol Head Neck Surg 2010;62(3):229–35.
Flash-evoked visual potentials in the early diagnosis of optic nerve injury due to craniofacial fractures. EEG EMG Z Elektroenzephalogr Elektromyogr VerwandteGeb 1991;22:224–29.
Controversies and current status of therapy of optic nerve damage in craniofacial traumatology and surgery. Mund Kiefer Gesichtschir 1999;3(4):176–94.
Indirect injury of the optic nerve. Neurosurgery 1984;14:756–64.
Blindness after maxillofacial blunt trauma. J Oral Maxillofac Surg 1994,22:220–25.
Pathological-clinical correlations. I. Indirect trauma to the optic nerves and chiasm (II). Certain cerebral involvements associated with defective blood supply. Invest Ophthalmol 1966; 5:433–49.
Optic nerve decompression in fibrous dysplasia: Indications, efficacy and safety. Plast Reconstr Surg 1997;99:22–30.
Delayed posttraumatic visual loss: A clinical dilemma. Pediatr Neurol 2000,22:133–35.
Transorbital sonographic monitoring of the optic nerve diameter in patients with severe brain injury. Transplant Proc 2006; 38:3700–06.
Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients. Ann Emerg Med 2007;49(4):508–14. Epub 2006 Sep 25.
Major orbital complications of endoscopic sinus surgery. Br J Ophthalmol 2001;85:598–603.
Retrobulbar anesthesia and retinal vascular obstruction. Ophthalmology 1983;90:373–77.
Surgical treatment of progressive visual loss in traumatic optic neuropathy. J Neurosurg 1989;70:799–801.
Das traumatische Optikusscheiden-hamatomund seine operative Behandlungsmoglichkeit. Klin Monatsbl Augenheilkd 1971;59:818–19.
Methylprednisolone treatment does not influence axonal regeneration or degeneration following optic nerve injury in the adult rat. J Neuroophthalmol 2004;24:11–18.
The treatment of traumatic optic neuropathy: The International Optic Nerve Trauma Study. Ophthalmology 1999;106:1268–77.
Surgery for traumatic optic neuropathy. Cochrane Database of Systematic Reviews 2005:CD005024.
Surgery for optic nerve injury: Should nerve sheath incision supplement osseous decompression? Skull Base 2009;19:263–72.
Outcome of traumatic optic neuropathy. Comparison between surgical and nonsurgical treatment. Acta Neurochir (Wien) 1999;141:27–30.
Treatment of traumatic optic neuropathy with high-dose corticosteroid. J Neuroophthalmol. Mar 2006; 26(1):65–67.
Powered instrumentation in orbital and optic nerve decompression. Otolaryngol Clin North Am Jun 1997;30(3):467–78.
Endoscopic optic nerve decompression. In endoscopic sinus surgery anatomy: Three-dimensional reconstruction and surgical technique. Thieme Medical Publishers, Inc. New York 2005:141–48.
Traumatic optic neuropathy: Where do we stand? Ophthal Plast Reconstr Surg May 2002;18(3):232–34.