Synopsis
Recognise an acute optic neuropathy, distinguish typical demyelinating optic neuritis from ischaemic, compressive, infectious and antibody-associated disease and coordinate urgent eye and neurological investigation.
- Typical demyelinating optic neuritis usually causes subacute monocular visual loss over hours to days, pain worsened by eye movement, reduced colour saturation, a central or caecocentral field defect and a relative afferent pupillary defect.
- The optic disc is often normal because inflammation is retrobulbar. A normal-looking disc does not exclude substantial optic-nerve dysfunction; marked swelling, haemorrhage or exudate is atypical and broadens the differential.
- Measure corrected acuity in each eye, red or colour perception, pupils, confrontation fields and fundi. A binocular acuity result or vague statement that vision is blurred cannot localise the lesion.
Key red flags
Subacute unilateral central visual loss, dyschromatopsia, eye-movement pain and a relative afferent pupil defect with a normal or mildly swollen disc in a younger adult supports typical optic neuritis.
Investigation priorities
Confirm objective afferent dysfunction, quantify severity and provide a baseline for recovery.
Management branches
Vision declines over minutes to days with pain, colour change, field loss or an afferent pupil defect.
- Obtain exact onset and systemic symptoms and perform corrected monocular acuity, colour, fields, pupils, fundi and a complete neurological and ocular-motor examination.
- Arrange same-day ophthalmic or neuro-ophthalmic assessment to exclude retinal vascular, giant-cell-arteritis, pressure and structural emergencies, sending ESR, CRP and platelets immediately when arteritis is possible.
Key medicines
High-dose methylprednisolone for selected demyelinating relapseWhen a neurologist or neuro-ophthalmologist recommends relapse treatment, use oral methylprednisolone 500 mg daily for five days, or intravenous methylprednisolone 1 g daily for three to five days when the NICE alternative criteria apply.