|Year : 2023 | Volume
| Issue : 1 | Page : 173-175
Blunt trauma–related optic nerve retraction: A novel entity
Sanchita Saini, Sandeep Saxena
Department of Ophthalmology, King George's Medical University, Shah Mina Road, King George's Medical University, Lucknow, Uttar Pradesh, India
|Date of Submission||04-Aug-2022|
|Date of Acceptance||19-Sep-2022|
|Date of Web Publication||20-Jan-2023|
King George's Medical University, Shah Mina Road, Lucknow, Uttar Pradesh - 226001
Source of Support: None, Conflict of Interest: None
A novel entity of optic nerve retraction following blunt trauma in a young boy is reported. Rotational injury of the globe following a fall from a bicycle resulted in optic nerve retraction within the scleral canal. On fundus examination, the scleral rim was visible, with peripapillary and vitreous hemorrhage and associated retinal detachment. Computed tomography of the orbit on axial section revealed an intact optic nerve at the posterior surface of the sclera.
Keywords: Optic nerve avulsion, optic nerve retraction, trauma
|How to cite this article:|
Saini S, Saxena S. Blunt trauma–related optic nerve retraction: A novel entity. Indian J Ophthalmol Case Rep 2023;3:173-5
Optic nerve avulsion (ONA) is defined as traumatic disinsertion of the nerve fibers at the disc margin but without damage to the disc sheath; is an uncommon form of traumatic optic neuropathy. ONA may result from intrusion of an object between the orbital wall and eyeball, sudden posterior movement of the optic nerve or anterior displacement or rotation of the eyeball, or acute rise in intraocular pressure due to deformation of the globe.
We report an unusual case of optic nerve retraction in an eight-year-old child following trauma by a fall from a bicycle.
| Case Report|| |
An eight-year-old boy presented to our tertiary care center with sudden loss of vision in his right eye following a fall from his bicycle two weeks back. There was no history of unconsciousness. On examination, there was a transverse laceration of 2 cm in length about 1.5 cm below the lower lid margin. The extraocular movement was full in all the gazes in both the eyes. There was afferent pupillary defect with no perception of light in the right eye and 6/6 visual acuity in the left eye. Anterior segment examination was unremarkable. On fundus examination of the right eye, the optic nerve head was pale and retracted. The surrounding scleral rim was visible with discontinuity of retinal blood vessels at the rim. Multiple peripapillary hemorrhages, vitreous hemorrhage, and retinal detachment were also observed [Figure 1]a. The examination of the left eye was unremarkable.
|Figure 1: (a) Pale and retracted optic nerve head with visible surrounding scleral rim and discontinuity of retinal blood vessels at the rim and multiple peripapillary, vitreous hemorrhage, and retinal detachment at presentation (two weeks after trauma). (b) Pale optic nerve head region with fibro-proliferative tissue obscuring the scleral rim. Resolving peripapillary and vitreous hemorrhage and detached retina with multiple folds at one-month follow-up|
Click here to view
The patient underwent fundus photography and spectral domain optical coherence tomography (SD-OCT). The SD-OCT could not be performed at the time of presentation due to poor cooperation of the child. At one month follow up, retinal nerve fiber layer (RNFL) analysis revealed flattening of the neuroretinal rim and RNFL [Figure 2]a. At three-month follow-up, similar findings were observed.
|Figure 2: (a) Spectral domain optical coherence tomography for retinal nerve fiber layer analysis showing flattening of the neuroretinal rim and retinal nerve fiber layer. (b) Contrast-enhanced computed tomography revealing intact optic nerve at outer scleral rim with no other abnormality|
Click here to view
Contrast-enhanced computed tomography (CECT) of orbit was performed and revealed intact optic nerve at outer scleral rim with no other abnormality [Figure 2]b.
On follow-up visits, the vision and the anterior segment findings were similar. The fundus examination at the one-month follow-up visit revealed pale optic nerve head region and presence of fibro-proliferative tissue that obscured the scleral rim. The peripapillary and vitreous hemorrhage started to resolve. The retina was detached and showed multiple folds [Figure 1]b.
At three-month follow up, fundus examination showed attenuation of retinal vessels. The peripapillary and vitreous hemorrhages resolved. Fibro-proliferative tissue covered the optic nerve head and the peripapillary region. The retina remained detached [Figure 3].
|Figure 3: Fibro-proliferative tissue completely covering the optic nerve head and peripapillary region with resolution of peripapillary and vitreous hemorrhage. The retina remains detached and retinal vessels are attenuated at three-month follow-up|
Click here to view
| Discussion|| |
Optic nerve avulsion is a rare and devastating entity that occurs following trauma and leads to irreversible blindness. The usual sites of involvement of the optic nerve following blunt trauma are intra-orbital part, intracanalicular part, or, rarely, the optic disc.
The intraocular part of the optic nerve extends from its anterior surface that is in contact with the vitreous to a plane, which is level with that of the posterior scleral surface. This has a dimension of approximately 1 mm. The choroid and all the elements of the retina except its axons end here. The axons bend at right angles into the nerve head and traverse posteriorly through the scleral canal. The axons of the optic nerve are most susceptible to trauma at the lamina cribrosa due absence of myelin sheath and lack of connective tissue that provides structural support.
Cirovic et al. studied the mechanism of optic nerve injuries in blunt trauma using finite element model of the eye, the optic nerve, and the orbit. The model was constructed to simulate blunt object trauma. The first phalanx (index finger) was used in the model to represent a blunt object. The results showed that the most likely mechanisms of injury included rapid rotation, lateral translation of the globe, and acute rise in the intraocular pressure (IOP). The impact caused rotation of the globe of up to 5000° per second, lateral velocities of up to 1 m/s, and IOP rise of over 300 mmHg. The main stress was observed at the insertion of the nerve into the sclera, at the side opposite to that of the impact. ONA causes shearing of retinal ganglion cell, hemorrhage in the supporting vasculature, and edema in the sheath which causes immediate and permanent loss of vision.
In another study by Sponsell et al., 59 porcine orbital mount eyes were taken to assess the paintball-induced impact. They observed that paintball impact produced rotation and eventual globe repulsion that was evident on high-speed film images. An impact of 1 to 13 joules was observed. They also suggested two trajectory-dependent mechanisms: (a) tangential glancing that produces strain-rate rotational avulsion, abscising the optic nerve, and (b) off-center direct impact that produces slower rotational-rebound avulsion, and breaching of the nerve posteriorly.
ONA can be accompanied by peripapillary and vitreous hemorrhage, and attenuation and occlusion of the vessels due to close proximity of the retinal vasculature with the optic nerve., Additionally, the association of ONA with retinal detachment is uncommon.
The present case represents a unique scenario of rotational injury resulting in retraction of the optic nerve within the scleral canal associated with retinal detachment.
| Conclusion|| |
Globe rotation–related injury also results in optic nerve retraction with irreversible visual loss.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Foster BS, March GA, Lucarelli MJ, Samiy N, Lessell S. Optic nerve avulsion. Arch Ophthalmol 1997;115:623-30.
Hykin PG, Gardner ID, Wheatcroft SM. Optic nerve avulsion due to forced rotation of the globe by a snooker cue. Br J Ophthalmol 1990;74:499-501.
Hillman JS, Myska V, Nissim S. Complete avulsion of the optic nerve. A clinical, angiographic and electrodiagnostic study. Br J Ophthalmol 1975;59:503-9.
Mackiewicz J, Tomaszewska J, Jasielska M. Optic nerve avulsion after blunt ocular trauma – Case report. Ann Agric Environ Med 2016;23:382-3.
Bron AJ, Tripathi RC, Tripathi BJ. Wolff's Anatomy of Eye and Orbit. 8th
ed. London: Chapman & Hall; 1997. p. 489.
Cirovic S, Bhola RM, Hose DR, Howard IC, Lawford PV, Marr JE, et al
. Computer modelling study of the mechanism of optic nerve injury in blunt trauma. Br J Ophthalmol 2006;90:778-83.
Sponsel WE, Gray W, Groth SL, Stern AR, Walker JD. Paintball trauma and mechanisms of optic nerve injury: Rotational avulsion and rebound evulsion. Invest Ophthalmol Vis Sci 2011;52:9624-8.
Gross CE, DeKock JR, Panje WR, Hershkowitz N, Newman J. Evidence for orbital deformation that may contribute to monocular blindness following minor frontal head trauma. J Neurosurg 1981;55:963-6.
Chong CCW, Chang AA. Traumatic optic nerve avulsion and central retinal artery occlusion following rugby injury. Clin Exp Ophthalmol 2006;34:88-9.
[Figure 1], [Figure 2], [Figure 3]