Case report: Anterior traumatic optic neuropathy with partial optic disc avulsion
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Traumatic optic nerve head avulsion and traumatic optic neuropathy are serious and can be visually devastating. Most cases have poor prognosis for visual recovery, leaving patients with minimal or no vision in the affected eye.
Traumatic optic neuropathy (TON) can be anterior or posterior and, if anterior, occurs with optic disc avulsion. This may be detected on fundus exam or may require additional imaging if obscured by vitreous hemorrhage. In cases of anterior TON with partial optic disc avulsion, a patient’s vision, color vision and visual field are affected; there is, however, hope for visual recovery, although it is difficult to predict long term.
The following case presents a patient who experienced blunt force trauma to his left eye during a physical altercation 20 years ago. The injury resulted in anterior TON with partial disc avulsion. The presence of a traumatic choroidal rupture with retinal nerve fiber layer (RNFL) thinning, enlarged blind spot and color desaturation in the affected eye were consistent with the reported diagnosis, but the excellent visual acuity was welcome news.
Case report
A 65-year-old Black man presented for a comprehensive eye exam. His last eye exam was 2 years ago (he was lost to follow-up after pandemic-related hospital restrictions). Twenty years ago, he experienced an ocular injury during an altercation, resulting in an “avulsed optic nerve of the left eye.” This was diagnosed and treated at another facility (the patient did not have access to the medical records but was a reliable historian).
Medical history included acid reflux, asthma and former smoker. Medications included fluticasone/salmeterol inhaler twice a day and albuterol inhaler as needed. There was no significant family medical or family ocular history to note.
With low hyperopic correction, visual acuity was 20/20 in each eye. Pupils were equal, round and reactive without afferent pupillary defect. Extraocular motility was full, and confrontation visual field testing also was full in each eye.
Red cap testing revealed color desaturation of 50% in the left eye compared with the right. Anterior segment exam was normal, and IOP via applanation tonometry was 13 mm Hg in the right eye and 15 mm Hg in the left eye at 11:00 a.m.
Dilated fundus exam revealed flat and normal macula and intact peripheral retina in each eye. The cup-to-disc ratio was 0.65 in the right eye and 0.7 in the left eye, both with perfused rim tissue. The left optic nerve had circumferential atrophy and a concentric crescent of choroidal rupture with accompanying fibrotic tissue inferior to the disc.
OCT of the RNFL was obtained. The right eye had an average RNFL thickness of 84 µm with flagged thinning temporally, and the left eye had an average RNFL thickness of 64 µm with superior, inferior and temporal thinning. Overall thinning of the macular ganglion cell complex of the left eye also was noted, with an average ganglion cell-inner plexiform layer thickness of 55 µm in the left eye compared with 69 µm in the right eye.
The most recent Humphrey visual field 30-2 test was performed 4 years ago and showed an enlarged blind spot with scattered superior, more than inferior, defects in the left eye; superior extension of the blind spot corresponded to the inferior optic nerve head damage that was evident funduscopically and on OCT. Visual field was full in the right eye.
To determine whether the left eye’s findings were suggestive of glaucoma or “red disease” — nomenclature referring to flagged RNFL erroneously appearing as glaucoma — a glaucoma progression analysis (GPA) was performed. On GPA, both eyes had stable findings over the past 5 years. Although glaucomatous optic neuropathy of the left eye had been a brief concern, the stability of OCT findings, along with desaturation and enlarged blind spot, was consistent with mild TON. The patient was asked to return in 6 months for repeat visual field and comparative analysis.
Discussion
Optic nerve head avulsion is a traumatic disinsertion of the optic nerve at the lamina cribrosa. The primary mechanism involved is sudden tractional force between the anterior and posterior aspects of the nerve insertion. Bell’s phenomenon, in which the eye rolls up and out as a protective instinct, can induce further torsional tension.
Sudden trauma can induce a drastic spike in IOP, creating an additional expulsion force on the optic nerve. After trauma, damage can also occur through coup and contrecoup phenomena. A 2023 study by Al Amry and colleagues found that the majority of optic nerve avulsion cases were among male patients (79%) aged 2 to 70 years.
There is no successful treatment for this condition, and it often leads to severe optic neuropathy and loss of vision in the affected eye. Optic nerve sheath fenestration and corticosteroids have been used as intervention but have not shown substantial improvement in vision recovery. Full optic nerve avulsion typically leads to light perception or no light perception vision. When the nerve is partially avulsed, the prognosis is variable, albeit still guarded.
Kawamata and colleagues presented a report of incomplete optic nerve avulsion after a badminton injury, in which vision recovered to 20/50, and Sturm and colleagues reported findings of a 6-year-old girl with partial optic nerve avulsion after a bicycle accident whose vision, originally no light perception, recovered to 20/200 several months after and remained stable to 4-year follow-up.
A differentiation must be made between TON with partial anterior optic disc avulsion and complete optic disc avulsion, which is more severe. The two can be distinguished using B-scan ultrasound, MRI or CT.
This patient was fortunate to have minimal visual repercussion from ocular trauma 20 years later. While TON sequelae persist, they do not affect his visual function or quality of life. Vision status and care immediately after the trauma are unknown because he was not a patient at our facility at that time, but the fact that he recovered to or maintained an acuity of 20/20 is worth reporting. Multimodal imaging analysis and careful examination over time will continue to keep us alerted of comorbidity or complication.
References:
- Al Amry M, et al. Clin Ophthalmol. 2023;doi:10.2147/OPTH.S426493.
- Ehlers JP, Shah CP. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. 5th ed. Wolters Kluwer; 2008:34,43-44.
- Kawamata Y, et al. Am J Ophthalmol Case Rep. 2022;doi:10.1016/j.ajoc.2022.101624.
- Mahjoub A, et al. Ann Med Surg (Lond). 2021;doi:10.1016/j.amsu.2021.102554.
- Pujari A, et al. Med Hypotheses. 2019;doi:10.1016/j.mehy.2019.02.031.
- Sturm V, et al. Acta Ophthalmol. 2010;doi:10.1111/j.1755-3768.2008.01444.x.
For more information:
Joseph Hallak, OD, PhD, FAAO, practices in Syosset, New York, and at Northport Veterans Affairs Medical Center. He can be reached at drjhallak@aol.com. Danielle Kalberer, OD, MBA, FAAO, also practices at Northport Veterans Affairs Medical Center and can be reached at danielle.kalberer@va.gov.
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