see also: [[Painful loss of vision]], [[Relative afferent pupillary defect|RAPD]] > **Optic neuritis**: sudden loss of vision (partial or complete), sudden blurred or foggy vision, pain on movement of the affected eye. ## Overview Typical optic neuritis is a primary, autoimmune inflammatory process of the optic nerve, affecting mostly young patients (range, 15 to 45 years old). It is the presenting symptom in 25% of cases of [[Multiple Sclerosis]] and may also be seen with other inflammatory, infectious, or autoimmune disorders. Patients with optic neuritis typically present with **monocular blurring** or fogginess of vision evolving over hours or days associated with variable degrees of pain with movement of the involved eye if the lesion is within the orbit. Patients may report fleeting flashes of light with eye movement, as well as worsening of vision with small increases in body temperature (from exercise, hot baths, or hot weather). Autoimmune optic neuritis often fluctuates with visual acuity reaching its poorest within 1 week and then slowly improving over the next several weeks. Approximately 30% of patients with acute optic neuritis develop multiple sclerosis within 5 years, and another 30% will have a recurrence within 10 years as the result of other causes. The natural history of atypical infectious and paraneoplastic etiologies of optic neuritis is concordant with the causative disease process. ## Findings - disturbed or blackened, rather than blurry, indicate moderate stage and require immediate medical attention to prevent further loss of vision - reduced night vision, photophobia, **red eyes** - loss of colour vision in affected eye, **especially red**, and otherwise washed out - may have [[Relative afferent pupillary defect]] ## causes - [[Multiple Sclerosis]] - [[toxic alcohols#Methanol]] (from formic acid) - SLE - infections (syphilis, lyme, [[Herpes zoster]]) - ischaemic otic neuropathy (thrombosis or embolism) ## OSCE - [EH-2025.1-MOCK-OSCE-Station-4-Examination](x-devonthink-item://3C7EF973-B708-434F-B298-DFDBA9BC9981)