What type of neuroimaging (Neuro Imaging) is recommended for a patient with monocular diplopia?

Neuroimaging for Monocular Diplopia

For patients with monocular diplopia, no neuroimaging is typically indicated as the cause is usually ophthalmologic rather than neurologic in nature. 1, 2, 3

Understanding Monocular vs. Binocular Diplopia

• Monocular diplopia: Double vision persists when one eye is covered; occurs in a single eye
• Binocular diplopia: Double vision resolves when either eye is covered; occurs due to misalignment between eyes

Diagnostic Approach for Monocular Diplopia

Initial Assessment

• Confirm monocularity by having the patient cover each eye separately
• If diplopia persists with one eye covered, it is monocular
• Perform basic eye examination:
  • Visual acuity testing
  • Refraction assessment
  • Pupillary examination
  • Slit lamp examination of anterior segment

Common Causes of Monocular Diplopia

1. Refractive errors (most common):

   • Astigmatism
   • Irregular corneal surface
   • Poorly fitting contact lenses

2. Ocular media abnormalities:

   • Cataracts
   • Corneal irregularities/scarring
   • Dry eye syndrome
   • Lens subluxation

3. Retinal disorders (less common):

   • Epiretinal membrane
   • Macular disease

4. Rare neurological causes:

   • Cerebral lesions (very rare)
   • Idiopathic intracranial hypertension (exceptional cases) 4

Imaging Recommendations

When Imaging is NOT Indicated

• Uncomplicated monocular diplopia with:
  • Normal ocular motility
  • Normal pupillary responses
  • Identifiable refractive or ocular media cause 1, 2

When to Consider Imaging

• Only if monocular diplopia is accompanied by:
  • Neurological symptoms or signs
  • Papilledema
  • Headache with concerning features
  • Visual field defects
  • Unexplained vision loss 1, 2

Imaging Modality if Indicated

• MRI brain with contrast is preferred if neurological cause is suspected 1
• CT orbits may be considered if orbital/structural abnormalities are suspected 1

Management Approach

1. Refer to ophthalmology for comprehensive evaluation 2
2. Address underlying cause:
   • Correct refractive errors with appropriate glasses
   • Treat dry eye syndrome
   • Consider cataract surgery if indicated
   • Manage other ocular surface disorders

Important Caveats

• Monocular diplopia rarely requires neuroimaging, unlike binocular diplopia which often does
• Patients with monocular diplopia should be referred to ophthalmology, not neurology 2
• If monocular diplopia is associated with headache, visual field defects, or other neurological symptoms, then neuroimaging may be warranted 4
• Psychogenic causes should be considered only after thorough ophthalmologic evaluation has ruled out organic causes 3

Remember that monocular diplopia is fundamentally different from binocular diplopia, and the diagnostic approach and imaging recommendations differ significantly between the two conditions.