Boy presents with decreased vision after accidental eye trauma
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A 7-year-old boy was referred to the neuro-ophthalmology clinic at the New England Eye Center for evaluation of decreased vision in the right eye.
One week before presentation, he was jumping on a trampoline with his brother, and his brother accidentally poked him in the right eye with his finger. He reported immediate eye pain, which resolved by that evening, but he was unsure of the initial quality of his vision. He denied any other ocular symptoms including flashes, floaters or light sensitivity. He was brought to his primary care provider the next day and was found to have difficulty counting fingers, so he was urgently referred to an ophthalmologist that same day. On exam, his vision was counting fingers at 1 foot in the right eye with superior optic nerve hemorrhage, but his overall exam showed no evidence of globe violation or orbital compartment syndrome.
Source: Kate V. Hughes, MD, and Thomas R. Hedges III, MD
The patient’s ocular history was notable for a corneal scar of the right eye secondary to a nail scratch as an infant. He was not on any ophthalmic medications and had no prior ophthalmic surgeries. He had no known medical history and was born full term without complications. His medication included melatonin. His family history was significant for type 2 diabetes in a maternal uncle and hypertension and glaucoma in his maternal grandmother. He had no known allergies. His review of systems was otherwise unremarkable.
Examination
Visual acuity without correction was 20/400 in the right eye with no improvement with pinhole and 20/20 in the left eye. Pupils were equal in size and reactive to light, with a trace afferent pupillary defect in the right eye. IOPs were 17 mm Hg in both eyes, with full extraocular motility and confrontation visual fields. External exam showed normal lids and adnexa with no edema or ecchymosis. Anterior segment exam of both eyes was unremarkable, except for an inferior subepithelial scar of the right cornea that was not in the visual axis. Posterior segment exam showed clear vitreous in both eyes without hemorrhage. The right optic nerve was notable for trace edema, mild nasal pallor and resolving disc hemorrhage superiorly (Figure 1). The left optic nerve was pink and healthy with a cup-to-disc ratio of 0.1. The macula was normal, and the peripheral retina was flat with no detachments or tears. Vessels were of normal caliber in both eyes.
OCT of the nerve fiber layer demonstrated crowded, thick nerves and slight retinal nerve fiber layer edema of the right eye (Figure 2). OCT of the macula and ganglion cell layers showed normal thickness (Figure 3).
What is your diagnosis?
See answer below.
Decreased vision
The differential diagnosis for decreased vision and peripapillary hemorrhage with an afferent pupillary defect in the setting of trauma can be categorized as traumatic or inflammatory.
Traumatic injury to the optic nerve can be either indirect or direct. The spectrum of injury can be broad, ranging from a mild contusion to complete avulsion of the optic nerve. Clinical exam may demonstrate signs of orbital or globe trauma, including absence of the optic disc, disc hemorrhage or edema. However, oftentimes the optic nerve itself appears unremarkable on presentation, only to develop atrophy with time. In addition, retrobulbar or optic nerve sheath hematoma can present with decreased vision in the setting of trauma. Symptoms of retrobulbar hematoma, a cause of orbital compartment syndrome, include severe ocular pain, proptosis and elevated IOP. Our patient did not have elevated IOP or proptosis on exam, even 1 day after the trauma. Less commonly, an optic nerve sheath hematoma causes direct compression and therefore localized compartment syndrome of the optic nerve. This may be difficult to diagnose clinically and typically requires imaging studies such as CT or MRI.
In terms of an inflammatory etiology, the exam findings of decreased vision and an afferent pupillary defect may be secondary to optic neuritis, whether typical or atypical, such as myelin oligodendrocyte glycoprotein. However, the patient’s young age would make this less likely, and it would be a coincidental finding to his recent trauma, as trauma is not a known risk factor. Another etiology, which would also be coincidental to the trauma, would be the possibility of an undiagnosed mass or tumor causing his symptoms. The patient may not have noticed his decreased vision until the trauma, which forced him to test each eye individually. For example, optic nerve glioma may be incidentally discovered after relatively trivial trauma.
Further evaluation
After seeing the outside ophthalmologist, the patient underwent a maxillofacial CT imaging the day after the trampoline accident, which showed no evidence of orbital injury, acute fracture, or retrobulbar or optic nerve pathology (eg, hematoma). Due to the presenting symptoms and exam findings, he was diagnosed with posterior direct traumatic optic neuropathy with partial optic nerve avulsion of the right eye in the setting of his brother’s finger poking his eye. The partial avulsion was likely producing the peripapillary hemorrhage.
Discussion
Traumatic optic neuropathy can be classified into two injury mechanisms: indirect or direct. The more common mechanism, indirect, is secondary to blunt force head trauma such as experienced in sports, motor vehicle accidents, falls and combat trauma. The mechanism of indirect traumatic optic neuropathy is not well understood, but it is believed to be from a shearing injury to the intracanalicular portion of the optic nerve. The optic nerve dura is continuous with the orbital periosteum of the sphenoid sinus, and the exiting optic nerve is thus susceptible to the transmission of force from blunt head trauma. This is especially particular to trauma affecting the superior orbital rim. The trauma force causes a shearing axonal injury to the nerve or a disruption of the blood supply, causing optic nerve edema within the canal. This increased luminal pressure causes secondary ischemia and further damage. This mechanism of injury is thought to parallel the same mechanism behind traumatic brain injuries.
The other mechanism of traumatic optic neuropathy, direct, is secondary to direct globe or retrobulbar nerve injury, such as from fingers (such as our patient or more commonly occurring during basketball) or objects (antennas, bungee cords) directly hitting the globe or optic nerve immediately behind the globe itself. This mechanism can lead to partial or complete avulsion of the optic nerve, optic nerve transection (typically from midfacial trauma and an orbital fracture), optic nerve sheath hemorrhage or orbital hemorrhage. The mechanism of the trauma can cause either a sudden retropulsion of the globe followed by a transient anterior translocation and/or sudden rotational force and/or acute increase in IOP, all causing traumatic optic nerve injury. Optic nerve avulsion is the most common form of optic nerve injury from direct trauma. This is most often caused by a severe rotation or torsional force of the globe, leading to rupture of the optic nerve fibers at the lamina cribrosa (a site of anatomical weakness due to the lack of supportive connective tissue) and anterior displacement of the globe. Even though the trauma is directly to the globe, there is often minimal external injury, demonstrated by our patient, and thus a careful dilated exam must be performed in patients experiencing eye trauma.
While the diagnosis of traumatic optic neuropathy can often be made clinically with examination of the posterior pole, direct visualization may be impossible if secondary to a more posterior injury or if vitreous hemorrhage is present. In these situations, further imaging such as B-scan ultrasound, CT or MRI can be helpful. However, several studies have reported that MRI may not be sensitive enough to detect all cases of trauma/avulsion, and B-scan ultrasound has also at times failed to detect optic nerve avulsions. Overall, additional imaging may assist in diagnosis but should be used in conjunction with a thorough history and clinical exam as the imaging may fail to detect the injury. Rarely, anterior ischemic optic neuropathy occurs from direct globe injury.
The management of traumatic optic neuropathy is controversial. Treatment options include observation, medical treatment with systemic corticosteroids and surgical treatment with optic nerve decompression. Steroid dosing is varied across the literature but in general involves 3 days of high-dose intravenous steroid followed by an oral taper. Arguments for treatment are based upon the hypothesis that a secondary injury to the axons occurs as a result of vasospasm and edema within the optic canal. Steroids may limit the free-radical amplification of the injury response.
The International Optic Nerve Trauma Study, which examined visual outcomes of traumatic optic neuropathy in eyes that were managed with steroids, surgical decompression or observation only, found no significant differences between the three groups and no indication that the dosage or timing of steroids or surgery was associated with an increased probability of visual improvement. In a 2020 randomized control trial by Chen and colleagues, surgical decompression vs. steroid treatment of indirect traumatic optic neuropathy was examined, with no significant differences found in improvement rate, degree or quality of patient life. Lastly, a 2020 report by the American Academy of Ophthalmology, reviewing interventions for indirect traumatic optic neuropathy, concluded that no consensus exists from studies published to date on a preferred treatment modality. In conclusion, the treatment of traumatic optic neuropathy must be customized for each individual patient.
Case conclusion
The risks and benefits of initiating steroid treatment vs. observation were discussed with the patient’s mother, who ultimately decided on observation as the patient was already 1 week out from the initial injury and his vision was improving. As the patient was an active child, monocular and safety precautions were discussed in detail. Unfortunately, after numerous attempts to reach the family, the patient was lost to follow-up.
- References:
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- Gupta D, et al. Traumatic optic neuropathy. https://eyewiki.aao.org/Traumatic_Optic_Neuropathy. Accessed July 10, 2022.
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- For more information:
- Kate V. Hughes, MD, and Thomas R. Hedges III, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Yi Ling Dai, MD, and Teresa P. Horan, MD. They can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.