What is the appropriate diagnosis and treatment for an adult with no known medical history experiencing double vision (diplopia)?

Approach to Double Vision in Adults

For an adult with no known medical history presenting with double vision, immediately determine if the diplopia is monocular (persists with one eye covered) or binocular (resolves with one eye covered), as this fundamentally directs the diagnostic pathway and urgency of evaluation. 1, 2

Initial Critical Distinction

Monocular vs. Binocular Diplopia:

• Monocular diplopia persists when covering the unaffected eye and typically indicates ocular pathology (refractive error, corneal irregularity, lens opacity, or macular disease) rather than neurologic emergency 3, 1
• Binocular diplopia resolves completely when either eye is covered and indicates ocular misalignment from neurologic, muscular, or orbital causes requiring urgent evaluation 1, 2, 4

Urgent Red Flags Requiring Same-Day Imaging

Immediately refer for urgent neuroimaging if any of the following are present: 4

• Headache accompanying diplopia
• Pupillary abnormalities (anisocoria, poor reactivity)
• Bradycardia, heart block, nausea, vomiting, or loss of consciousness (suggests oculocardiac reflex from orbital trauma) 5
• Acute onset with other neurologic signs

Essential History Elements

Obtain specific details about: 5

• Timing: Sudden vs. gradual onset; duration of symptoms
• Pattern: Constant vs. intermittent; worse at distance vs. near; directional (horizontal, vertical, oblique)
• Trauma history: Any recent orbital or head trauma, even minor
• Prior eye conditions: Childhood strabismus, amblyopia, previous eye surgeries, or patching 5
• Recent vision changes: New glasses, monovision contact lenses, cataract surgery, or refractive surgery 5
• Systemic symptoms: Fatigue suggesting myasthenia, pain suggesting inflammation

Comprehensive Examination Protocol

Perform the following systematic evaluation: 5

Visual Function Assessment:

• Visual acuity with current correction
• Pupillary examination (rule out third nerve palsy)
• Confrontational visual fields
• Intraocular pressure measurement
• Slit-lamp examination
• Dilated fundus examination with attention to macular pathology and fundus torsion 5

Motility and Alignment Testing:

• Versions (binocular eye movements in all gaze positions) 5
• Ductions (monocular eye movements to detect restriction) 5
• Cover-uncover and alternate cover testing with prism measurement in primary position, upgaze, downgaze, and lateral gazes 6, 7
• Forced duction testing if restriction is suspected (distinguishes mechanical restriction from paresis) 5
• Saccades and smooth pursuit evaluation 5

Specialized Testing When Indicated:

• Maddox rod, Lancaster red-green, or Hess screen testing for complex misalignments 5
• Amsler grid if macular disease suspected 5, 3
• Lights on/off test for dragged-fovea diplopia syndrome (pathognomonic when diplopia disappears in complete darkness but returns with room lights on) 5, 3

Diagnostic Categories and Management

Post-Traumatic Diplopia

If orbital trauma history is present: 5

• Obtain CT imaging (not MRI if metallic foreign body possible) 5
• Look for orbital fractures, muscle entrapment, hemorrhage, or edema 5
• Observe for 6 months before surgical intervention, as many cases resolve spontaneously 5
• Diplopia persisting beyond 6 months is unlikely to resolve without treatment 5

Cranial Nerve Palsies (Including Post-Herpetic)

For isolated nerve palsies: 6

• Observe for 4-6 months as most resolve spontaneously, particularly microvascular causes 6, 4
• Provide occlusion (patch or tape) for immediate relief, though this sacrifices depth perception 6
• Apply Fresnel prisms to glasses for temporary relief during observation period 6
• Consider botulinum toxin injection for conservative temporary management 6
• Wait minimum 4-6 months before strabismus surgery to ensure deviation has stabilized 6

Macular Disease with Binocular Central Diplopia

When macular pathology is identified: 5, 3

• Recognize that 16-37% of patients with epiretinal membranes or maculopathy develop binocular central diplopia 5, 3
• Understand that prism or strabismus surgery alone will not resolve symptoms because the underlying problem is foveal image mismatch, not simple misalignment 5
• Fogging one eye is the most successful long-term treatment: use Bangerter foils, Scotch Satin tape on spectacle lens, or occlusive contact lenses 5, 3
• Small amounts of prism combined with Bangerter foil may provide better relief in difficult cases 5, 3
• Coordinate care with retina specialist for potential membrane peeling, though this improves diplopia in only some patients and may cause new diplopia in others 5, 3

Fixation Switch Diplopia

For patients with childhood strabismus history who develop new diplopia: 5

• Most commonly caused by monovision for presbyopia (38%), myopia in previously preferred eye (25%), or incorrect refractive correction (38%) 5
• Attempt to switch fixation back to the previously dominant eye through refractive correction 5
• Optimize vision in the newly dominant eye if fixation cannot be switched back due to permanent vision loss 5
• Screen all patients undergoing refractive surgery (especially monovision) with history of childhood eye disease, patching, or muscle surgery 5

Imaging Strategy

Order CT (not MRI) if: 5

• Any concern for orbital trauma or fracture
• Possible ferrous-metallic foreign body
• Acute presentation with red flags

Order MRI if: 1, 2

• Isolated cranial nerve palsy without clear microvascular risk factors
• Progressive symptoms
• Multiple cranial nerve involvement
• Associated neurologic signs

Treatment Algorithm by Timeframe

Acute Phase (0-6 months):

• Observation is appropriate for most isolated nerve palsies and post-traumatic cases 5, 6
• Occlusion or Fresnel prisms for symptomatic relief 6
• Optimize refractive correction 5

Chronic Phase (>6 months):

• Strabismus surgery if deviation has stabilized and conservative measures inadequate 5, 6
• Ground-in prisms for stable, small deviations 6
• Fogging techniques for macular-related diplopia 5, 3

Critical Pitfalls to Avoid

Do not assume all "double vision" is true diplopia - many patients use this term to describe blur or visual distortion rather than true image separation 3

Do not rush to surgery before 4-6 months in traumatic or inflammatory cases, as premature intervention may result in overcorrection when spontaneous improvement would have occurred 5, 6

Do not perform strabismus surgery for macular-related diplopia without first confirming that superimposition of foveal images by synoptophore or prism actually reduces subjective diplopia 5

Do not miss coexisting treatable causes - patients with macular diplopia may also have other forms of strabismus that respond to treatment 5, 3

Referral Patterns

Refer to neuro-ophthalmology or strabismus specialist for complex cases, acute nerve palsies requiring localization, or when surgical intervention is being considered 5, 3

Refer to retina specialist when macular pathology is identified as the cause 5, 3

Coordinate care between retina and strabismus specialists for binocular central diplopia cases 5, 3