Double Vision

Differential Diagnosis

Common Diagnoses

  • Physiological (Focusing too Near, or Perceiving Objects Nearer than those Focused on)
  • Intoxication: Prescribed Sedation, Non-prescribed Drugs, Especially Excess Alcohol, Opiates, Benzodiazepines
  • Stroke
  • Mild Head Injury, Causing Temporary Diplopia
  • Facial Bone Trauma: Orbital and Zygomatic Fracture

Occasional Diagnoses

  • Mononeuropathy (e.g. Diabetes, MS)
  • Orbital Disease (Usually Associated with Pain and Proptosis) and after Surgery (Scarring Limiting Globe Movement)
  • Guillain–Barré Syndrome
  • Palsy of Third, Fourth or Sixth Cranial Nerves due to Intracranial Space-occupying Lesion (Haemorrhage, Tumour, Aneurysm, Abscess, Cavernous Sinus Thrombosis)
  • Myasthenia Gravis
  • Monocular Diplopia: Early Cataract, Irregularity of Corneal Surface (e.g. Post Trauma or Inflammation)

Rare Diagnoses

  • Ophthalmoplegic Migraine
  • Tolosa–hunt Syndrome: Granulomatous or Inflammatory Process in Anterior Portion of Cavernous Sinus or Superior Orbital Fissure
  • Pseudoparalysis of Ocular Muscles: Dysthyroid Disease; Duane’s Syndrome (Congenital Fibrosis of Lateral Rectus)
  • Orbital Myositis
  • Pituitary Exophthalmos

Ready Reckoner

Key distinguishing features of the most common diagnoses

PhysiologicalIntoxicationStrokeHead InjuryFacial Bone Trauma
History of TraumaNoNoNoYesYes
Unequal PupilsNoNo Possible PossibleNo
Unilateral Limb ParesisNoNo Possible PossibleNo
Impaired ConsciousnessNoYes Possible PossibleNo
Facial Bone DeformityNoNoNoNoYes

Possible Investigations

Likely:none; FBC, ESR/CRP, lipid studies, urinalysis, fasting glucose or HbA1c.

Possible:TFT, X-rays, CT/MRI scan.

Small Print:Edrophonium test, EMG, CSF studies, angiography.

  • No investigation is indicated in primary care for the most common causes – referral is the likeliest course of action.
  • FBC, ESR/CRP, lipid studies: If stroke suspected and admission not required. FBC and ESR/CRP will also provide evidence of inflammatory conditions.
  • Urinalysis for glucose/fasting glucose or HbA1c: To investigate possible diabetes.
  • TFT will reveal hyperthyroidism.
  • Other investigations (and possibly some of the above) are likely to be carried out in secondary care: Skull and facial bone X-rays in trauma cases; CT or MRI scan (head injury, stroke, MS, space-occupying lesion); specialist neurological investigations (edrophonium test, singlefibre EMG studies, CSF examination, angiography).

Top Tips

  • Establish if the diplopia is binocular or not. Uniocular double vision has a much narrower differential diagnosis.
  • Take time to clarify the symptom. Sometimes, patients complain of ‘double vision’ when they really mean blurring – and vice versa.
  • The cover test is a reliable way to find out which eye is affected.
  • Fourth cranial nerve palsy produces diplopia on looking downwards and inwards, often noticed when descending stairs. The patient may try to compensate by tilting the head – so-called ocular torticollis.

Red Flags

  • Intoxication in conjunction with a head injury is commonly seen in custody medicine and A&E departments. Admission for neurological observation is strongly recommended.
  • Diplopia of acute onset may well reflect serious pathology – refer for urgent assessment.
  • Intermittent diplopia should not be dismissed too readily as insignificant – remember that myasthenia gravis and multiple sclerosis are possibilities.
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