What is the appropriate workup for a patient presenting with diplopia (double vision)?

Workup for Diplopia

The appropriate workup for diplopia must include a detailed sensorimotor examination, determination of monocular versus binocular diplopia, and appropriate neuroimaging based on clinical findings to identify the underlying cause. 1

Initial Assessment

Distinguish Monocular vs. Binocular Diplopia

• Monocular diplopia: Persists when one eye is covered (suggests ocular causes)
• Binocular diplopia: Resolves when either eye is covered (suggests neurologic, muscular, or mechanical causes)

Key History Elements

• Onset (sudden vs. gradual)
• Pattern (constant vs. intermittent)
• Direction of maximum separation (horizontal, vertical, torsional)
• Associated symptoms (pain, ptosis, neurological symptoms)
• Past ocular history (strabismus, surgery, trauma)
• Medical conditions (diabetes, hypertension, thyroid disease)
• Medications

Essential Examination Components

• Visual acuity and refraction
• Pupillary examination (size, reactivity, anisocoria)
• Ocular motility assessment in all nine positions of gaze
• Cover/uncover and alternate cover testing
• Forced duction testing when restriction is suspected
• Exophthalmometry if proptosis is present
• Slit-lamp and dilated fundus examination

Specialized Testing

For Suspected Retinal Causes

• Amsler grid testing for metamorphopsia
• M-Charts for quantifying metamorphopsia
• Awaya test for aniseikonia
• For dragged-fovea diplopia syndrome: lights on/off test or optotype-frame test 2

For Suspected Neuromuscular Causes

• Double Maddox rod testing for torsional misalignment
• Lancaster red-green testing
• Hess screen testing
• Synoptophore testing (if central fusion disruption is suspected) 2

Neuroimaging Guidelines

Based on clinical findings, appropriate imaging should be ordered:

• Orbital trauma or suspected metallic foreign body: CT Orbits (non-contrast) 1
• Suspected extraocular muscle or soft tissue abnormalities: MRI Orbits with contrast 1
• Suspected brainstem, cavernous sinus, or cranial nerve pathology: MRI Brain with contrast 1
• Suspected aneurysm (especially with pupil-involving 3rd nerve palsy): CT angiography or MR angiography 2
• Suspected cavernous sinus thrombosis: CT and CT venogram 3

Laboratory Testing

• Patients >60 years with recent onset diplopia: Check ESR and CRP to rule out giant cell arteritis 1, 3
• Suspected myasthenia gravis: Acetylcholine receptor antibodies, MuSK antibodies 4
• Suspected infectious causes: Consider testing for syphilis and Lyme disease 2
• Suspected inflammatory/demyelinating disease: Consider lumbar puncture (glucose, protein, cell count, cytology) 2

Special Considerations by Presentation

Acute Isolated Third Nerve Palsy

• Immediate neuroimaging with CT and CT angiography to rule out compressive aneurysm 3
• Check for pupil involvement (pupil-sparing suggests microvascular cause, pupil-involving suggests compressive lesion) 2

Isolated Fourth or Sixth Nerve Palsy

• In the absence of other neurological signs, can be referred to Neurology or Ophthalmology for further workup rather than immediate ED imaging 3
• Consider vascular risk factors (diabetes, hypertension) as potential causes 2

Internuclear Ophthalmoplegia

• MRI Brain with contrast to evaluate for demyelinating disease, stroke, or other brainstem pathology 1

Suspected Orbital Disease

• Contrast-enhanced CT of brain and orbits for suspected orbital apex syndrome, retro-orbital mass, or thyroid eye disease 3

Pitfalls to Avoid

• Don't rely on unenhanced plain CT: Generally not useful in diplopia workup 3
• Don't miss vital sign abnormalities with orbital trauma: Bradycardia or heart block may indicate oculocardiac reflex from muscle entrapment requiring urgent intervention 1
• Don't overlook retinal causes: Consider retinal etiology if the patient has small or no deviation on cover testing but persistent diplopia 1
• Don't assume all cases need immediate imaging: Isolated 4th and 6th nerve palsies without other neurological signs can often be referred for outpatient workup 3

By following this systematic approach to diplopia evaluation, clinicians can effectively identify the underlying cause and implement appropriate management strategies to improve patient outcomes.