Mubeen Hasan

Summary

Optic neuritis is a common cause of sudden visual loss and is often associated with demyelinating diseases such as multiple sclerosis. This case report highlights an unusual presentation of bilateral optic neuritis in a young patient with atypical clinical features, emphasizing the diagnostic challenges, the disease’s underlying pathophysiology, and the importance of appropriate investigation and management.

Introduction

Optic neuritis typically presents as unilateral, painful vision loss in young adults, frequently linked to demyelinating conditions like multiple sclerosis (MS) (1). Atypical presentations, such as painless or bilateral visual loss, necessitate a broader differential diagnosis, including autoimmune, infectious, and inflammatory etiologies. This report discusses the diagnostic and therapeutic challenges of managing bilateral optic neuritis in a previously healthy young patient.

Case Presentation

A 24-year-old male presented to the emergency department with acute, painless, bilateral vision loss and dyschromatopsia. He denied any preceding illness, ocular trauma, or systemic symptoms. His past medical and family history was unremarkable.

On examination, visual acuity was 6/60 bilaterally, and a relative afferent pupillary defect was absent. Fundoscopy revealed bilateral optic disc swelling with scattered flame-shaped retinal haemorrhages. There was no evidence of anterior uveitis or vitritis. Neurological examination was normal.

Magnetic resonance imaging (MRI) of the orbits and brain revealed bilateral optic nerve enhancement without evidence of demyelinating brain lesions (2). Cerebrospinal fluid analysis was unremarkable, with no oligoclonal bands. Laboratory investigations, including autoimmune markers (ANA, ANCA), infectious serologies (Lyme, syphilis, HIV), and inflammatory markers, were negative.

The patient was treated empirically with intravenous methylprednisolone (1 g daily for 5 days) due to the severity of visual loss. Oral prednisolone was tapered over 6 weeks. At follow-up, visual acuity improved to 6/9 bilaterally, and optic disc swelling had resolved.

Discussion

Optic neuritis is characterized by inflammation of the optic nerve, leading to vision loss and dyschromatopsia (1). While unilateral involvement is typical, bilateral presentations are uncommon and raise suspicion for alternative diagnoses such as neuromyelitis optica spectrum disorder (NMOSD), infectious optic neuropathy, or paraneoplastic syndromes.

In this case, bilateral optic neuritis with atypical features required thorough investigation to exclude systemic causes. The absence of demyelinating brain lesions and negative aquaporin-4 and myelin oligodendrocyte glycoprotein (MOG) antibodies made NMOSD less likely. Similarly, negative infectious and autoimmune workups ruled out other potential causes.

The Optic Neuritis Treatment Trial (ONTT) demonstrated that high-dose corticosteroids expedite recovery of visual function but do not alter long-term outcomes (3). While steroids remain the mainstay of treatment for severe cases, their role in atypical presentations remains less well-defined.

Conclusion

This case underscores the need for a comprehensive diagnostic approach to optic neuritis, especially in patients with atypical presentations. Early recognition and prompt exclusion of systemic causes are essential. Although corticosteroids may hasten recovery, their long-term impact on visual prognosis is limited, as highlighted by the ONTT. Further studies are needed to explore management strategies for atypical cases.

References

1. Petzold A, Plant GT. Diagnosis and classification of optic neuritis. Lancet Neurol. 2014;13(1):83-93.
2. Toosy AT, Mason DF, Miller DH. Optic neuritis. Lancet Neurol. 2014;13(1):83-99.
3. Beck RW, Cleary PA, Trobe JD, et al. The effect of corticosteroids for acute optic neuritis on the subsequent development of multiple sclerosis. N Engl J Med. 1993;329(24):1764-1769.