eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Trauma

Traumatic Optic Neuropathy

Author: Christopher I Zoumalan, MD, Clinical Instructor, Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, New York University Medical Center and Manhattan Eye, Ear, and Throat Hospital
Coauthor(s): Jonathan W Kim, MD, Director of Oculoplastic and Orbital Surgery, Co-director of Ocular Oncology Service, Co-director of Neuro-ophthalmology Service, Department of Ophthalmology, Stanford Medical Center; James W Gigantelli, MD, Professor of Ophthalmology, Assistant Dean of Government Relations, University of Nebraska Medical Center
Contributor Information and Disclosures

Updated: Jul 28, 2008

Introduction

Traumatic optic neuropathy (TON) refers to an acute injury of the optic nerve secondary to trauma. The optic nerve axons may be damaged either directly or indirectly and the visual loss may be partial or complete. An indirect injury to the optic nerve typically occurs from the transmission of forces to the optic canal from blunt head trauma. This is in contrast to direct TON, which results from an anatomical disruption of the optic nerve fibers from penetrating orbital trauma, bone fragments within the optic canal, or nerve sheath hematomas. 

Problem

Patients with TON can present with a variable degree of vision loss (decreased visual acuity, visual field abnormalities, or loss of color vision). Most cases (up to 60%) present with severe vision loss of light perception (LP) or worse. In the acute phase, the optic nerve usually appears normal on funduscopic examination, but optic nerve atrophy is often seen 3-6 weeks after the injury.

Frequency

The incidence of TON in the setting of a closed traumatic head injury in various studies ranges from 0.5-5%. The vast majority of TON cases are seen in males (up to 85%), with a mean age of 34 years. Motor vehicle and bicycle accidents account for the majority of causes, followed by falls and assaults. TON has also been associated with penetrating orbital trauma (eg, stab wounds, pellet and gunshot wounds, foreign bodies) and recreational sports (eg, paint ball injury).   

Pathophysiology

The pathophysiology of TON is thought to be multifactorial, and some researchers have also postulated a primary and secondary mechanism of injury. In indirect TON cases, the injury to the axons is thought to be induced by shearing forces that are transmitted to the fibers or to the vascular supply of the nerve. Studies have shown that forces applied to the frontal bone and malar eminences are transferred and concentrated in the area near the optic canal. The tight adherence of the optic nerve’s dural sheath to the periosteum within the optic canal is also thought to contribute to this segment of the nerve being extremely susceptible to the deformative stresses of the skull bones. Such injury leads to ischemic injury to the retinal ganglion cells within the optic canal.

A secondary mechanism can result in optic nerve swelling after the occurrence the acute injury. The optic nerve swelling can exacerbate retinal ganglion cell degeneration by further compromising the vascular blood supply, either through a rise in intraluminal pressure or reactive vasospasm. These secondary mechanisms, in theory, form the rationale for optic canal decompression via medical (ie, steroids) or surgical means (ie, bony decompression). Finally, the intracranial segment of the optic nerve may be damaged by forces delivered to the axons by the shifting of the brain following head trauma. With this mechanism, the nerve fibers may be injured against the falciform dural fold or through a shearing force where the nerve becomes fixed as it enters the intracranial opening of the optic foramen.

Relevant Anatomy

The human orbit is composed of seven bones that comprise 4 walls: the roof, lateral wall, medial wall, and floor. The 7 bones include: ethmoid, frontal, lacrimal, maxillary, palatine, sphenoid (lesser and greater wings), and zygomatic bones. The 4 orbital walls converge posteriorly at the apex of the orbit, and the optic canal is located within the lesser wing of the sphenoid, which is one of the bones that comprise the orbital roof. 

The optic canal is separated from the superior orbital fissure by the optic strut of the sphenoid bone; hence the optic strut comprises the optic canal's lateral wall. The canal's medial wall separates it from the sphenoid sinus. Structures that pass through the optic canal include the optic nerve sheath and axons, their supportive glia, the ophthalmic artery, and branches of the carotid sympathetic plexus of the autonomic nervous system.

The optic nerve is a cable of retinal ganglion cells that enters the eye approximately 4 mm nasally and 0.8 mm superiorly from the center of the macula at the posterior pole. Inside the eyeball, the anterior optic nerve forms the optic disc, which is visible clinically with funduscopic examination as a pink, slightly elevated structure centered upon the opening in the posterior sclera.
 
The optic nerve is a collection of axons (approximately 1.2 million) originating from the retinal ganglion cells. With its meningeal sheath, the optic nerve is 3-4 mm in diameter and its total length measures approximately 50 mm from the globe to the optic chiasm. The nerve is composed of intraocular (about 1 mm), intraorbital (20-30 mm), intracanalicular (5-11 mm), and intracranial (3-16 mm) segments. The axons transmit visual stimuli from the retina to the eight primary visual nuclei in the lateral geniculate nucleus.

The topographic organization of the axons, as arranged by the retina, is relatively preserved within the optic nerve. In addition to the visual input that it carries to the lateral geniculate nucleus, the optic nerve also carries afferent fibers that participate in the pupillary responses. Except for its intraocular segment, the axons of the optic nerve are myelinated. Similar to the cerebral white matter, the optic nerve is ensheathed by oligodendrocytes, which are responsible for the production of myelin. Astrocytes are also present within the glial septa, and they provide nutritional support to the axons.

Throughout its intraorbital course, the optic nerve remains surrounded by pia, arachnoid, and dura mater, which move along with the optic nerve during normal eye movements. Within the optic canal, the sheath of the optic nerve is fused to the sphenoid periosteum, and, as a result, the nerve and its sheath are tightly fixed to the bony canal within this confined space. At the posterior foramen of the optic canal, the optic nerve sheath fuses with an overlying falciform fold of dura that lines the calvaria.

Pial branches of the internal carotid, anterior cerebral, and anterior communicating arteries perfuse the intracranial optic nerve. Small pial branches from the ophthalmic artery supply the intracanalicular optic nerve. The intraorbital optic nerve is also supplied by perforating branches derived from the ophthalmic artery. The arterial circle of Zinn-Haller supplies the intraocular optic nerve with contributions from the posterior ciliary arteries, the pial arterial network, and the peripapillary choroidal vasculature.

More on Traumatic Optic Neuropathy

Overview: Traumatic Optic Neuropathy
Workup: Traumatic Optic Neuropathy
Treatment: Traumatic Optic Neuropathy
Follow-up: Traumatic Optic Neuropathy
Multimedia: Traumatic Optic Neuropathy
References
[ CLOSE WINDOW ]

References

  1. Bracken MB, Shepard MJ, Collins WF, et al. A randomized, controlled trial of methylprednisolone or naloxone in the treatment of acute spinal-cord injury. Results of the Second National Acute Spinal Cord Injury Study. N Engl J Med. May 17 1990;322(20):1405-11. [Medline].

  2. Edwards P, Arango M, Balica L, et al. Final results of MRC CRASH, a randomised placebo-controlled trial of intravenous corticosteroid in adults with head injury-outcomes at 6 months. Lancet. Jun 4-10 2005;365(9475):1957-9. [Medline].

  3. Levin LA, Beck RW, Joseph MP, et al. The treatment of traumatic optic neuropathy: the International Optic Nerve Trauma Study. Ophthalmology. Jul 1999;106(7):1268-77. [Medline].

  4. Steinsapir KD. Treatment of traumatic optic neuropathy with high-dose corticosteroid. J Neuroophthalmol. Mar 2006;26(1):65-7. [Medline].

  5. Steinsapir KD, Goldberg RA, Sinha S, et al. Methylprednisolone exacerbates axonal loss following optic nerve trauma in rats. Restor Neurol Neurosci. 2000;17(4):157-163. [Medline].

  6. Steinsapir KD, Seiff SR, Goldberg RA. Traumatic optic neuropathy: where do we stand?. Ophthal Plast Reconstr Surg. May 2002;18(3):232-4. [Medline].

  7. Yu-Wai-Man P, Griffiths PG. Steroids for traumatic optic neuropathy. Cochrane Database Syst Rev. Oct 17 2007;CD006032. [Medline].

  8. Cook MW, Levin LA, Joseph MP, et al. Traumatic optic neuropathy. A meta-analysis. Arch Otolaryngol Head Neck Surg. Apr 1996;122(4):389-92. [Medline].

  9. Wang BH, Robertson BC, Girotto JA, et al. Traumatic optic neuropathy: a review of 61 patients. Plast Reconstr Surg. Jun 2001;107(7):1655-64. [Medline].

  10. Bracken MB, Shepard MJ, Holford TR, et al. Administration of methylprednisolone for 24 or 48 hours or tirilazad mesylate for 48 hours in the treatment of acute spinal cord injury. Results of the Third National Acute Spinal Cord Injury Randomized Controlled Trial. National Acute Spinal Cord Injury Study. JAMA. May 28 1997;277(20):1597-604. [Medline].

  11. Carta A, Ferrigno L, Salvo M, et al. Visual prognosis after indirect traumatic optic neuropathy. J Neurol Neurosurg Psychiatry. Feb 2003;74(2):246-8. [Medline].

  12. Girard BC, Bouzas EA, Lamas G, et al. Visual improvement after transethmoid-sphenoid decompression in optic nerve injuries. J Clin Neuroophthalmol. Sep 1992;12(3):142-8. [Medline].

  13. Goldberg RA, Steinsapir KD. Extracranial optic canal decompression: indications and technique. Ophthal Plast Reconstr Surg. Sep 1996;12(3):163-70. [Medline].

  14. Goldenberg-Cohen N, Miller NR, Repka MX. Traumatic optic neuropathy in children and adolescents. J AAPOS. Feb 2004;8(1):20-7. [Medline].

  15. Holmes MD, Sires BS. Flash visual evoked potentials predict visual outcome in traumatic optic neuropathy. Ophthal Plast Reconstr Surg. Sep 2004;20(5):342-6. [Medline].

  16. Kountakis SE, Maillard AA, El-Harazi SM, et al. Endoscopic optic nerve decompression for traumatic blindness. Otolaryngol Head Neck Surg. Jul 2000;123(1 Pt 1):34-7. [Medline].

  17. Levin LA, Beck RW, Joseph MP, et al. The treatment of traumatic optic neuropathy: the International Optic Nerve Trauma Study. Ophthalmology. Jul 1999;106(7):1268-77. [Medline].

  18. Li KK, Teknos TN, Lauretano A, et al. Traumatic optic neuropathy complicating facial fracture repair. J Craniofac Surg. Sep 1997;8(5):352-5; discussion 356-9. [Medline].

  19. Medeiros FA, Moura FC, Vessani RM, et al. Axonal loss after traumatic optic neuropathy documented by optical coherence tomography. Am J Ophthalmol. Mar 2003;135(3):406-8. [Medline].

  20. Medeiros FA, Susanna R Jr. Retinal nerve fiber layer loss after traumatic optic neuropathy detected by scanning laser polarimetry. Arch Ophthalmol. Jun 2001;119(6):920-1. [Medline].

  21. Miyahara T, Kurimoto Y, Kurokawa T, et al. Alterations in retinal nerve fiber layer thickness following indirect traumatic optic neuropathy detected by nerve fiber analyzer, GDx-N. Am J Ophthalmol. Aug 2003;136(2):361-4. [Medline].

  22. Ohlsson M, Westerlund U, Langmoen IA, et al. Methylprednisolone treatment does not influence axonal regeneration or degeneration following optic nerve injury in the adult rat. J Neuroophthalmol. Mar 2004;24(1):11-8. [Medline].

  23. Rajiniganth MG, Gupta AK, Gupta A, et al. Traumatic optic neuropathy: visual outcome following combined therapy protocol. Arch Otolaryngol Head Neck Surg. Nov 2003;129(11):1203-6. [Medline].

  24. Steinsapir KD, Goldberg RA. Traumatic optic neuropathy. Surv Ophthalmol. May-Jun 1994;38(6):487-518. [Medline].

  25. Sucher NJ, Lipton SA, Dreyer EB. Molecular basis of glutamate toxicity in retinal ganglion cells. Vision Res. Dec 1997;37(24):3483-93. [Medline].

  26. Tsai HH, Jeng SF, Lin TS, et al. Predictive value of computed tomography in visual outcome in indirect traumatic optic neuropathy complicated with periorbital facial bone fracture. Clin Neurol Neurosurg. Apr 2005;107(3):200-6. [Medline].

  27. Wang BH, Robertson BC, Girotto JA, et al. Traumatic optic neuropathy: a review of 61 patients. Plast Reconstr Surg. Jun 2001;107(7):1655-64. [Medline].

  28. Yip CC, Chng NW, Au Eong KG, et al. Low-dose intravenous methylprednisolone or conservative treatment in the management of traumatic optic neuropathy. Eur J Ophthalmol. Jul-Aug 2002;12(4):309-14. [Medline].

  29. Yu Wai Man P, Griffiths PG. Surgery for traumatic optic neuropathy. Cochrane Database Syst Rev. Oct 19 2005;CD005024. [Medline].

  30. Zimmer-Galler IE, Bartley GB. Orbital emphysema: case reports and review of the literature. Mayo Clin Proc. Feb 1994;69(2):115-21. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

traumatic optic neuropathy, optic neuropathy, optic nerve injury, vision loss, trauma, frontal trauma, orbital trauma, optic nerve avulsion, optic nerve transection, diffuse orbital hemorrhage, localized orbital hemorrhage, optic nerve sheath hematoma, orbital emphysema, TON

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Christopher I Zoumalan, MD, Clinical Instructor, Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, New York University Medical Center and Manhattan Eye, Ear, and Throat Hospital
Christopher I Zoumalan, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American Medical Association, American Society of Ophthalmic Plastic and Reconstructive Surgery, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.

Coauthor(s)

Jonathan W Kim, MD, Director of Oculoplastic and Orbital Surgery, Co-director of Ocular Oncology Service, Co-director of Neuro-ophthalmology Service, Department of Ophthalmology, Stanford Medical Center
Jonathan W Kim, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American Society of Ophthalmic Plastic and Reconstructive Surgery, and North American Neuro-Ophthalmology Society
Disclosure: Nothing to disclose.

James W Gigantelli, MD, Professor of Ophthalmology, Assistant Dean of Government Relations, University of Nebraska Medical Center
James W Gigantelli, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, American Society of Ophthalmic Plastic and Reconstructive Surgery, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.

Medical Editor

Hassan H Ramadan, MD, MSc, Professor and Vice-Chair, Department of Otolaryngology-Head and Neck Surgery, Professor, Department of Pediatrics, West Virginia University
Hassan H Ramadan, MD, MSc is a member of the following medical societies: American Academy of Otolaryngic Allergy, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, and American Rhinologic Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Stephen G Batuello, MD, Consulting Staff, Colorado ENT Specialists
Stephen G Batuello, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Physician Executives, American Medical Association, and Colorado Medical Society
Disclosure: Nothing to disclose.

CME Editor

Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders
Christopher L Slack, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine
Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Head and Neck Society
Disclosure: Covidien Corp Consulting fee Consulting; US Tobacco Corporation unstricted gift unknown

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.