Red flags in diplopia
- Persistent headaches
- Changes in pupillary size
- Drooping of the eyelids
- Ocular fatigue on excessive use
- Loss of vision
- Existing neurological symptoms, such as weakness of arm, face, or leg, or dysphasia
- Excessive alcohol history
- Protruding eyeballs
- History of recent facial trauma
Diplopia, or double vision, is not a common presentation in primary care. However, it is important to be aware of and recognise the conditions that may present with this symptom.
Diplopia can be classified as monocular or binocular. It may be found as a result of a systemic review or feedback from an optician or hospital.
Causes of diplopia
- Refractive errors
- Myasthenia gravis
- Horner’s syndrome, which has a number of aetiologies. For example, apical lung tumour or dissecting carotid artery
- Intracranial pathology, for example, tumour, abscess, haemorrhage
- Strabismus in children
- Orbital floor fracture
- Cranial nerve palsies III, IV, VI
- Certain drugs, such as opiates
- Alcohol intoxication
- Temporal arteritis
It is very important to establish what the patient means by double vision, how it is affecting their life and whether they drive a vehicle. Most patients tend to have researched their symptoms on the internet, so understanding their ideas, concerns and expectations of the problem is also important.
Questions to ask
It is vital to establish:
- What does the patient mean by double vision? It is important to differentiate this from blurred vision.
- How long have they been experiencing it?
- How is it affecting them?
- Have they noticed any other change in their vision?
- Have they recently visited an optician? If yes, what was the outcome? Is there an opticians report that you can refer to?
- Have they experienced this before and if so, what was the outcome of any consultations they may have had?
- Have they noticed any change to their pupil?
- Have they noticed any new squints?
- Have their eyelids started to droop?
- Have they noticed any tiredness associated with the eyes?
- Are there any associated headaches? If so, it is important to establish the cause of the headache.
- Have they noticed any weakness of the arm, face or leg?
- Have they noticed any scalp tenderness or pain on chewing?
- Have the eyeballs changed in shape or size?
- A systemic review may be necessary, depending on the answers to the previous questions. It will probably be clear if there has been a history of facial trauma.
- Has the patient started any new medication? Smoking, drug and alcohol history may be relevant.
- What does the patient think is causing the problem?
- How does this symptom affect them day-to-day?
- Do they drive?
When to refer
If intracranial pathology is suspected, two-week neurological referral may be required.
If the presentation is acute, with additional signs and symptoms, same-day referral may be necessary.
Persistent symptoms with no clear cause may warrant neurological assessment.
If alcohol excess is suspected, referral to local drug and alcohol services may be appropriate.
Remote examination via telephone consultation
If relevant, the patient may be able to check their pulse and BP. You can identify whether there is an obvious speech defect and ask about any ‘FAST’ symptoms that can be explored.
Remote examination via video consultation
Look for any obvious eye changes, facial weakness or dysphasia. Ask the patient if they can provide a BP or pulse measurement.
If face-to-face examination is needed, ensure you have the correct PPE.
Examination needs to be focused on the history. Inspect the eyelids and the pupils. Is there any obvious drooping or discrepancy in size of the pupils? Is there any obvious cranial nerve palsy? Look for proptosis.
Check visual acuity - ensure you have a Snellen chart. It may be necessary to see if the pupils are equal and to check reaction to light and accommodation. Check the range of eye movements.
If relevant, a more detailed neurological examination may be necessary. You may need to check for temporal artery tenderness.
A history of facial trauma should prompt examination of the facial bones to exclude an orbital floor fracture.
Primary care and other investigations
- Blood tests including ESR, TSH and fasting glucose/HbA1c may be useful. LFTs may also be indicated if you suspect alcohol is a causative agent.
- Plain chest X-ray if you suspect Horner's syndrome.
- Outpatient CT/MRI head - this will not be available to all GPs, so refer to your local rules.
Dr Pipin Singh is a GP in Northumberland. This article was updated by the author in April 2021.