Diplopia

Question 1

What are the features of abducens nerve palsy?

Answer 1

Unable to look laterally in affected eye
Sudden onset horizontal diplopia - worse when looking on affected side
Convergent squint

Question 2

What can cause abducens nerve palsy?

Answer 2

Poor blood supply - due to hypertension, diabetes, high cholesterol, or smoking
Direct pressure on abducens nerve - due to tumours, middle ear infections, aneurysm of neighbouring blood vessels, or raised ICP compressing 6th CN
Head injuries
Inflammation in region of nerve
Idiopathic intracranial hypertension (IIH) - found in obese, young women that have papilloedema, abx use (tetracyclines for acne) and weight gain

Question 3

What investigations can be carried out in abducens nerve palsy?

Answer 3

Refer to orthoptist and ophthalmologist
Examination to test squint
Bloods and MRI to investigate causes e.g. raised ICP

Question 4

What is the treatment for abducens nerve palsy?

Answer 4

Usually self-limiting, unless it is caused by trauma
Patch over eye
Fresnel prism
Botox

Question 5

What are the features of third nerve palsy?

Answer 5

Partial ptosis with depressed and divergent (down + out) eye
Pupil dilation that is unreactive to light - this makes it a MEDICAL EMERGENCY
If headache present, suggests a mass affecting 3rd CN

Question 6

What are causes of third nerve palsy?

Answer 6

Vasculitis
Aneurysm - berry aneurysms are common near posterior communicating artery so can compress 3rd CN
Tumour
Hernia

Question 7

What are the features and causes of 4th nerve palsy?

Answer 7

Nasal upshot of eye

Caused by congenital or trauma

Question 8

What type of trauma to orbit can cause diplopia?

How is this managed?

Answer 8

Inferior orbital floor fracture (blow out fracture)

Management:
Refer to maxfax
IV abx then switch to oral
Advise not to blow nose so they don’t get bacteria from sinus into orbit leading to orbital infection

Question 9

DVLA rule about driving with diplopia

Answer 9

Advise patient with diplopia to stop driving and notify DVLA immediately
Patient can return to driving after a period of adaptation or if double vision has resolved
Can hold a Group 1 license (Cars/personal vehicles) if their double vision is controlled with prisms or if they occlude (patch) one eye
The other eye however must have sufficient vision (6/12) and adequate visual field (need to see 120 degrees in periphery in at least 1 eye)
Drivers of HGV cannot drive with persistent diplopia, even after period of adaptation or patched