Optic nerve avulsion associated with central retinal artery occlusion following rotational globe injury.

Avulsion of the optic nerve head is a rare and severe complication of ocular blunt trauma. Herein, we describe a case of 16-year-old boy, who presented with a rare combination of optic nerve avulsion associated with central retinal artery occlusion, following blunt trauma with a leather ball. This report highlights the potential blinding complication following rotational injury.

Optic nerve avulsion (ONA) is defined as a traumatic disinsertion of the nerve fibers at the disc margin, without damage to the disc sheath, and is an uncommon form of traumatic optic neuropathy.[1] Central retinal artery occlusion (CRAO) primarily occurs due to emboli originating from atherosclerotic carotid artery. In young adults, it may be seen in association with migraine, coagulation abnormalities, cardiac disorders, and rarely trauma. Traumatic occlusions have been seen in patients suffering from head injury and in those with eyeball contusions.[2] This report describes a case of rare combination of ONA associated with CRAO due to forceful rotation of the globe following blunt injury in a young adult.

Case Report

A 16-year-old boy presented to our emergency services, with complaints of sudden loss of vision following accidental injury to his right eye with a leather ball, while playing cricket. There was no history of unconsciousness and epistaxis. External eye examination showed lid ecchymosis and subconjunctival hemorrhage. Visual acuity in the right eye was no light perception. Pupillary examination showed total afferent pupillary defect. Extraocular movements were normal. Intraocular pressure was 12 mmHg. Fundus examination showed an excavation in the optic nerve head region with no visible optic disc. The hollow in the optic disc region was surrounded by a zone of bare choroid with multiple peripapillary hemorrhages. The surrounding retina showed retinal edema associated with segmentation of blood column, arteriolar attenuation, and retinal opacification at the macula, which was suggestive of CRAO [Fig. 1a]. The left eye examination was normal. Computed tomography (CT) scan showed that right globe was intact and was displaced inferiorly. A disruption of optic nerve at its attachment to the eyeball was present with fluid density in-between [Fig. 1b]. There was no evidence of any orbital wall fracture. A diagnosis of traumatic optic nerve head avulsion complicated with CRAO was established.

Figure 1

(a) Fundus photograph of the right eye showing excavation in the optic disc area, peripapillary hemorrhages, retinal edema, and segmentation of blood column in vessels. (b) Axial computed tomography scan showed an intact right globe with inferior displacement and disruption of optic nerve at the attachment to globe with fluid density in-between

Discussion

ONA is a rare presentation of ocular trauma. The optic nerve is susceptible to being avulsed at three locations including the optic disc, the orbital apex, and the optic chiasma. Most commonly, the ONA is encountered following road traffic accidents, sporting injuries, and falls.[3] A literature search showed finger gouging in sports as frequent cause of injury.[4] Ocular trauma caused by door handles has also been reported.[5]

The possible mechanisms of ONA include direct trauma to the globe, shearing forces from acute globe rotation, and sudden increase in intraocular pressure that forces the nerve out of the scleral canal. All result in tearing of the fibers at the level of the lamina cribrosa. In the present case, the sudden injury with the leather ball may have caused a severe, forced rotation of the globe with extreme abduction of eyeball causing the optic nerve to avulse from the weaker posterior sclera.

The diagnosis of ONA is usually apparent if the media is clear. The fundus examination shows an excavation in the optic disc area.[6] However, in most of the reports in literature, the disc area was obscured by vitreous hemorrhage, and the diagnosis in such scenario was established with ultrasonography or imaging. On ultrasound, a posterior ocular wall defect in the region of the optic nerve head may be apparent.[7] CT scan with thin sections is helpful in delineating the posterior scleral wall defect corresponding to the avulsed optic nerve. In our case, characteristic-excavated ONH was seen on fundus examination, due to clear media. It is essential to confirm the diagnosis so that the patient may not be subjected to unnecessary treatment such as optic nerve decompression or high-dose corticosteroids.

CRAO after blunt trauma, though rare, can be caused by compression of the central retinal artery by a hematoma, by air in case of orbital emphysema, or raised intraorbital pressure resulting from swelling of orbital soft tissue.[8] In these conditions, damage to the endothelial cells of the artery stimulates platelet aggregation and thrombus formation. As there was no evidence of orbital hematoma, possible mechanism of CRAO in our case was severe reflex vasospasm initiated as a direct response to concussion injury to the arterial wall smooth muscle.

The association of ONA with CRAO is extremely rare and have been reported once by Chong et al.[9] They confirmed diagnosis of CRAO with fundus fluorescein angiography; however, no optic nerve abnormality was seen on CT scan. Neovascular glaucoma has been reported as a delayed complication in CRAO with ONA.[10] Authors advocate close follow-up and intraocular pressure monitoring in such scenario.

Conclusion

This report highlights the potential sight-threatening complication of sports injury with a leather ball. We insist that it is important to consider this uncommon but visually catastrophic condition in the differential diagnosis of acute posttraumatic vision 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.

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Conflicts of interest

There are no conflicts of interest.