Diplopia

Question 1

Probability diagnosis

Answer 1

Binocular: Ocular nerve palsy (3,4,6) various causes:

• CVA/TIA
• ​diabetes
• trauma
• multiple sclerosis
• Ophthalmoplegic migraine
• Physiological (disparateness)
• Drug effect e.g. alcohol, benzodiapines

Monocular:

• early cataract
• refractive error
• cornea diseases
• dislocated lens
• psychogenic (rare)

Question 2

Serious disorders not to be missed

Answer 2

Vascular:

• CVA/TIA

Infection:

• Intraocular abscess
• Sinusitis
• Botulism
• HIV/AIDS

Tumour/cancer:

• Involving 3, 4 or 6 cranial nerves

Other:

• Facial bone trauma/head injury
• Guillain-Barré syndrome

Question 3

Pitfalls (often missed)

Answer 3

Any orbital infiltration

Rarities:

• Multiple sclerosis
• Myasthenia gravis
• Orbital myositis
• Cavernous sinus thrombosis
• Wernicke’s encephalopathy

Question 4

Masquerades checklist

Answer 4

Diabetes: mononeuritis

Drugs e.g. sedatives, opioids, alcohol

Thyroid/other endocrine: hyperthyroid

Question 5

Is the patient trying to tell me something?

Answer 5

A consideration if nil findings.

Some cases are idiopathic.

Question 6

Key history

Answer 6

If one or both eyes

Intermittent, or constant

Associated pain.

Neurological symptoms incl. other cranial nerve dysfunction

Associated general symptoms such as weight loss and fever.

PMHx diabetes, hypertension and cerebrovascular disease

Drug hx, esp. alcohol or illicit, prescription and OTC drugs.

Question 7

Key examination

Answer 7

General features: appearance of patient, vital signs

Inspection of the eyes and neck (goitre)

Ocular motility

Visual acuity

Establish if binocular or monocular

Test for diplopia with each eye occluded

• if it persists it is uniocular, if it disappears it is binocular.

Perform the cover test

Cranial nerves in general

Other basic neurological examination

Ophthalmoscopy

Question 8

Key investigations

Answer 8

Nil for most cases

First line:

• urinalysis
• blood sugar
• FBE
• ESR/CRP

Consider:

• TFTs
• imaging if indicated (refer)

Question 9

Diagnostic tips

Answer 9

Refer urgently if;

• diplopia is binocular
• of recent onset and
• persistent.

Other ‘red flags’ incl.

• pupil involvement
• pain, proptosis
• any other neurological s/s.

Question 10

The onset of double vision in adults can be:

Answer 10

Uniocular (confined to one eye)

or

Binocular, usually due to extraocular muscular imbalance or weakness.

Question 11

Direction of movement of the right eye indicating the?

Answer 11

responsible extra-ocular muscles

and

cranial nerves (3 = oculomotor, 4 = trochlear, 6 = abducens)