Unit 2: Visual field defects, double vision & optic disc swelling

Third nerve palsy (oculomotor nerve) can have varying signs & symptoms depending on the aetiology.

A painful unilateral third nerve palsy suggests a posterior communicating artery aneurysm this requires urgent Neurological assessment.

Diabetes and hypertension often cause microvascular palsy that spares the pupil.

Other causes:

• Trauma
• Neoplasm
• Migraine
• Giant cell arthritis

Third nerve supplies:

• Superior Rectus
• Inferior Rectus
• Medial Rectus
• Inferior Oblique

The lateral rectus is supplied by the 6th nerve

The superior oblique is supplied by the 4th nerve

The superior oblique and lateral rectus work unopposed to produce a exo hypo deviation so the eye takes a down and out position +/- a dilated pupil. (see above)