What are the symptoms of optic neuritis?

Symptoms of Optic Neuritis

The classic symptoms of optic neuritis include painful vision loss, periocular pain that worsens with eye movement, and dyschromatopsia (color vision impairment). 1, 2

Primary Symptoms

• Unilateral vision loss that typically develops over hours to days (subacute onset) 1, 2
• Pain with eye movement (present in approximately 90% of cases) 1, 2
• Dyschromatopsia (impaired color vision, often more severe than the reduction in visual acuity) 2
• Reduced contrast sensitivity, which may persist even after visual acuity improves 2
• Visual field defects, commonly central scotomas 3, 2
• Red-green color desaturation (colors appear washed out or less vibrant) 3

Clinical Examination Findings

• Afferent pupillary defect (weaker direct pupillary light reflex in the affected eye) 1
• Approximately one-third of patients have a mildly edematous optic disc (papillitis) 1, 4
• The majority of cases have retrobulbar optic neuritis (normal-appearing optic disc despite symptoms) 4, 5
• Visual acuity may range from mild impairment to complete vision loss 2

Associated Symptoms

• Photophobia (sensitivity to light) 3
• Temporary worsening of vision with increased body temperature (Uhthoff's phenomenon) 6
• Visual symptoms that fluctuate throughout the day 2
• Phosphenes (flashes of light) with eye movement in some cases 5

Clinical Course

• Visual symptoms typically progress over days to 2 weeks 1
• Pain usually precedes or accompanies visual loss 2
• Spontaneous improvement occurs in approximately 95% of cases, even without treatment 1
• Recovery typically begins within 2-3 weeks and continues for several months 2, 5
• Some visual parameters (contrast sensitivity, color vision, visual field) may remain impaired despite good recovery of visual acuity 2

Diagnostic Features on Imaging

• MRI evidence of optic nerve inflammation shows increased T2 signal, gadolinium enhancement, and optic nerve swelling 3
• Coronal fat-suppressed T2-weighted sequences are optimal for visualizing optic nerve lesions 3
• Typical acute optic nerve lesions are characterized by T2 hyperintensity, associated optic nerve swelling, and contrast enhancement 3

Red Flags for Atypical Optic Neuritis

• Bilateral simultaneous involvement (more common in neuromyelitis optica spectrum disorders) 3, 6
• Severe vision loss with poor recovery 6, 4
• Posterior optic nerve involvement including the chiasm (suggestive of anti-AQP4-IgG-seropositive neuromyelitis optica spectrum disorders) 3
• Long optic nerve lesions (suggestive of neuromyelitis optica spectrum disorders and especially anti-MOG-IgG disease) 3
• Perioptic nerve sheath enhancement or soft tissue enhancement extrinsic to the nerve 3

Relationship to Multiple Sclerosis

• Optic neuritis is often the presenting manifestation of multiple sclerosis 1, 5
• The risk of developing multiple sclerosis after an episode of optic neuritis can be assessed with brain MRI 1
• The presence of even one clinically silent T2 hyperintense brain lesion in patients with optic neuritis is highly associated with eventual MS diagnosis 3

Understanding these symptoms is crucial for early diagnosis and appropriate management of optic neuritis, which can lead to better visual outcomes and proper assessment of the risk for developing multiple sclerosis or other demyelinating disorders.