Dr Sarah Walker-Date
University Hospitals Dorset
Aims
This article aims to improve junior doctor’s ability to assess and manage patients presenting with diplopia. Diplopia is an important sign to be able to recognise, often being the first manifestation of a serious systemic, muscular or neurological disorder.
Introduction
Diplopia vision means seeing two images instead of one. This may occur horizontally or vertically.
Any disruption of the ocular muscles or the nerves supplying them can result in diplopia (1).
| Diplopia | Cause | Comments |
|---|---|---|
| Binocular | Strabismus | Occurs when the eyes cannot align correctly. Common presentation in children. |
| Thyroid Dysfunction | Changes in thyroid function can affect external ocular muscles. Such as, Graves ophthalmoplegia due to adipose tissue build at the back of the eye | |
| Vascular | Strokes, aneurysm and diabetes can all affect blood supply to eye muscles and nerves. | |
| Neurology | Myasthenia gravis, multiple sclerosis and brain tumour | |
| Trauma | Orbital fracture | |
| Monocular | Dry eyes | |
| Keratoconus | ||
| Cataracts | ||
| Maculopathy | ||
| Temporary | Alcohol | |
| Drugs | including diazepam, opioids and seizure medications | |
| Concussion |
History – Key points to establish:
1. Binocular or monocular
· Often the patient will be unclear if it is unilateral or bilateral
· Ask the patient to cover each eye and assess if the diplopia resolves on covering a particular eye
· Monocular is commonly due to a cornea or lens anomalies, dry eyes, stigmatism or cataract
2. Timing of onset
· Sudden onset requires urgent assessment
3. Gaze dependent
· If the double vision worsens when looking in certain directions this will help identify specific extraocular muscles and the underlying aetiology
4. Vertical vs Horizontal
· Horizontal diplopia is commonly due to medial or lateral rectus muscle pathology or the nerves supplying these muscles (Cranial Nerve (CN) VI or III)
· Vertical diplopia is commonly due to superior oblique muscle or CN IV pathology
5. Trauma
· An orbital fracture can lead to diplopia through muscle or nerve impingement. This is an ophthalmology emergency.
6. Vascular Risk Factors
· Ischemic cranial nerve palsies are a common cause in elderly and comorbid patients. It is important to take a thorough history to elicit risk factors such as diabetes, hypertension, hyperlipidaemia, smoking history, previous stroke or MI.
7. Variability
· Fluctuation in symptoms throughout the day associated with fatigue suggests myasthenia gravis or decompensating strabismus.
8. Headache
· Elderly patients presenting with diplopia associated with a headache must have temporal arteritis excluded, due to risk of permanent visual loss.
Examination and Investigations
A full neurological and ophthalmologic exam should be carried out, including Hirschberg testing and head tilt test. Blood pressure and blood glucose are useful investigations if a vascular cause is suspected. Bloods should include thyroid function tests and anti-acetylcholine.
If acute onset or associated neurological signs an urgent MRI or CT is required, and an urgent ophthalmology review(3).
Summary
With the increasing demands within the NHS, it is becoming ever more important for junior doctors to be able to recognise and manage ophthalmological presentations. This article is aimed at improving understanding of important differentials for diplopia and eliciting key points in your history to identify the causes.
References
1. Alves M, Narciso M. Diplopia: A Diagnostic Challenge with Common and Rare Etiologies. Am J Case Rep.2015; 16:220-223
2. Jain, S. Diplopia: Diagnosis and management. Clinical Medicine. 2022; 22(2) 104-106
3. https://eyewiki.aao.org/Basic_Approach_to_Diplopia [Accessed 20 Jan 2023]