What are the symptoms of optic neuritis in a patient, potentially with a history of autoimmune disorders such as multiple sclerosis?

Symptoms of Optic Neuritis

Optic neuritis typically presents with a triad of subacute painful vision loss developing over hours to days, pain worsening with eye movement, and red-green color desaturation (dyschromatopsia). 1

Core Clinical Features

Visual Symptoms

• Vision loss develops subacutely over hours to days, not instantaneously 1, 2
• Central scotomas (blind spots in the center of vision) are the most common visual field defect 1
• Red-green color desaturation (dyschromatopsia) is characteristic and often more pronounced than the degree of vision loss would suggest 1, 3
• Photophobia (light sensitivity) commonly accompanies the visual symptoms 1

Pain Characteristics

• Periocular pain (around the eye) that worsens with eye movement is present in the majority of cases 1, 2
• Pain typically precedes or accompanies vision loss 4
• Important caveat: While pain is typical, approximately 8% of cases may present painlessly, which should not exclude the diagnosis 3

Physical Examination Findings

• Relative afferent pupillary defect (RAPD) is present in unilateral cases—the affected eye has a weaker direct pupillary light reflex 4
• Optic disc appearance varies: approximately one-third of patients have mild optic disc edema, while two-thirds have a normal-appearing disc initially (retrobulbar neuritis) 2
• Optic nerve atrophy or pallor develops in chronic cases 1

Red Flags for Atypical Optic Neuritis

Certain features suggest atypical forms (such as neuromyelitis optica spectrum disorders or MOG-antibody disease) that require different management:

• Bilateral simultaneous involvement 1, 5
• Severe vision loss with poor recovery after steroids or steroid dependence 5, 6
• Prominent optic disc edema (more than mild swelling) 5, 6
• Posterior optic nerve involvement extending to the chiasm 1, 5
• Childhood or late adult onset (typical ON occurs ages 20-40) 4, 6

Relationship to Multiple Sclerosis

For patients with autoimmune disorders like multiple sclerosis:

• Optic neuritis is often the presenting manifestation of MS in 15-20% of cases 2, 7
• Even one clinically silent T2 hyperintense brain lesion on MRI is highly associated with eventual MS diagnosis 1
• The presence of brain lesions dramatically increases MS risk, with hazard ratios of 5.1 for 1-3 lesions and 11.3 for ≥10 lesions 1

Prognosis

• Visual recovery occurs in 95% of cases of typical optic neuritis, regardless of treatment 2
• Recovery typically begins within 2-3 weeks, with maximal improvement by 3-6 months 2
• High-dose intravenous methylprednisolone speeds recovery but does not improve final visual outcome 2