Synopsis
Examine the afferent, efferent and brainstem functions of the cranial nerves systematically, then localise single and multiple deficits while recognising neuro-ophthalmic and bulbar emergencies.
- Start with observation of eyelid position, pupil size, eye alignment, facial symmetry, voice, articulation, secretion handling and spontaneous eye movements before following a numbered sequence.
- Test visual acuity in each eye with habitual correction before interpreting colour, fields, pupils or fundi; a binocular result can hide severe unilateral impairment.
- Confrontation fields localise pre-chiasmal, chiasmal and retrochiasmal dysfunction only as a screen. Repeat carefully and arrange formal perimetry or urgent imaging when the history and field defect require it.
Key red flags
Monocular acuity or colour loss, a central field defect, relative afferent pupillary defect and disc swelling or later pallor suggests optic neuropathy. Pain on eye movement favours optic neuritis but is neither required nor specific.
Investigation priorities
Quantify afferent visual dysfunction and determine whether the pattern is pre-chiasmal, chiasmal or retrochiasmal.
Management branches
Sudden diplopia or ptosis with ocular-motor deficit, pupillary abnormality, severe headache, orbital signs or additional neurology.
- Perform ABCDE, glucose, acuity, pupils, fields, eye position and movements, face and limb examination; document onset, pain, trauma, anticoagulation, diabetes and vascular history.
- Discuss immediately with stroke, neurology, ophthalmology and neuroradiology according to local arrangements and obtain urgent vascular and structural imaging suited to aneurysm, stroke, cavernous sinus or orbital disease.