Diplopia

INTRODUCTION

The onset of double vision in adults can be uniocular (confined to one eye) or binocular, usually due to extraocular muscular imbalance or weakness.

Examples of:

• uniocular diplopia: early cataract, dislocated lens, psychogenic (rare)

• binocular diplopia: ocular nerve palsies (3, 4 or 6) (e.g. CVA, TIA, diabetes, trauma, multiple sclerosis) (Fig. D7)

Test for diplopia with each eye occluded—if it persists it is uniocular, if it disappears it is binocular. Refer urgently if binocular, if recent onset and persistent.

CRANIAL NERVES IN GENERAL (WITH FUNCTION)

1. Olfactory nerve—sensory for smell

2. Optic nerve—sensory for vision

3. Oculomotor—3 eye movements, eyelid closure, pupil constriction

4. Trochlear—down and in eye movement

5. Trigeminal—mastication, facial sensation

6. Abducens—abduction of eye

7. Facial nerve—motor for eye closure and facial muscles, taste anterior ⅔ tongue

8. Acoustic nerve—sensory for hearing and balance

9. Glossopharyngeal—motor to palate and pharynx, sensory to pharynx and taste posterior ⅓ tongue

10. Vagus—motor to palate, pharynx, larynx, sensory to pharynx and larynx (gag reflex)

11. Accessory—motor to trapezius and sternomastoid muscles

12. Hypoglossal—motor for tongue movement