What questions should be asked to a patient with double vision to determine the underlying cause, considering their medical history, demographics, and current medications, including anticonvulsants (seizure medications), antidepressants, and blood pressure medications?

Essential Questions to Ask a Patient with Double Vision

Begin by determining whether the diplopia is monocular or binocular by asking the patient to cover each eye separately—if the double vision persists with one eye covered, it is monocular and suggests an ocular problem like cataracts or refractive error; if it resolves when either eye is covered, it is binocular and indicates ocular misalignment requiring neurologic evaluation. 1, 2, 3

Critical Initial Questions

Monocular vs. Binocular Distinction

• Does the double vision go away when you cover either eye? This single question is the most important discriminator—binocular diplopia disappears when either eye is covered, while monocular diplopia persists when covering the unaffected eye 2, 4, 3

Temporal Pattern

• When did the double vision start—suddenly or gradually? Sudden onset suggests vascular events (stroke, aneurysm), while gradual onset may indicate compressive lesions, thyroid eye disease, or myasthenia gravis 5, 2, 4
• Is it constant or intermittent? Intermittent diplopia that worsens with fatigue strongly suggests myasthenia gravis 1, 2

Directional Characteristics

• In which direction of gaze is the double vision worst? Horizontal diplopia worse at distance suggests sixth nerve palsy, while vertical diplopia suggests fourth nerve palsy or skew deviation 5, 2, 4
• Are the images side-by-side (horizontal) or one above the other (vertical)? This helps localize which cranial nerve or muscle is affected 2, 4

Red Flag Questions (Require Urgent Neuroimaging)

Associated Neurologic Symptoms

• Do you have severe headache, especially new or different from usual? This may indicate giant cell arteritis, aneurysm, or increased intracranial pressure 6, 5
• Have you noticed any drooping of the eyelid, pupil changes, or facial numbness? Pupil involvement with third nerve palsy suggests aneurysm until proven otherwise 5, 2
• Do you have weakness, numbness, difficulty speaking, or balance problems? These suggest brainstem stroke or multiple sclerosis 6, 5, 4
• Do you experience dizziness or vertigo with the double vision? This combination raises concern for brainstem lesions affecting both the sixth nerve and vestibular nuclei 6

Progressive or Multiple Involvement

• Is the double vision getting progressively worse? Progressive symptoms suggest compressive lesions or inflammatory processes 5
• Do you have double vision in multiple directions or affecting both eyes? Bilateral sixth nerve involvement or multiple cranial nerve palsies indicate serious pathology 5

Medical History Questions

Past Ocular History

• Did you have any eye problems as a child, such as lazy eye, patching, or eye muscle surgery? This is critical for identifying fixation switch diplopia in patients with childhood strabismus who develop new diplopia from changes in fixation preference 1
• Do you have any history of retinal problems, macular degeneration, or epiretinal membranes? Between 16-37% of patients with maculopathy develop binocular central diplopia from foveal misregistration 1, 7

Systemic Conditions

• Do you have diabetes, high blood pressure, or thyroid disease? Diabetes and hypertension are common causes of microvascular cranial nerve palsies, while thyroid eye disease causes restrictive myopathy 5, 2, 8
• Have you had any recent infections, particularly respiratory infections? This may precede Miller Fisher syndrome or other post-infectious neuropathies 2
• Do you have any autoimmune diseases or cancer? These increase risk for inflammatory or paraneoplastic causes 2, 9

Medication Review

• Are you taking any new medications, particularly anticonvulsants, antidepressants, or blood pressure medications? While less common, certain medications can affect ocular motility or cause diplopia 4

Functional Impact Questions

Pattern and Severity

• Does the double vision worsen as the day progresses or with prolonged use of your eyes? Fatigable diplopia is pathognomonic for myasthenia gravis 1, 2
• Does lying down or changing head position affect the double vision? Vertical diplopia from skew deviation is more likely to improve with supine positioning than trochlear nerve palsies 2
• In what percentage of your visual field do you experience double vision? This quantifies severity and helps track progression—diplopia can range from 5% to 100% of the binocular field of gaze 8

Specific Testing Questions for Macular Causes

• When you look at a single letter on a screen, is the letter single but the frame around it double (or vice versa)? This optotype-frame test identifies dragged-fovea diplopia syndrome where peripheral fusion overrides central fusion 1, 7
• Do you see wavy or distorted lines when looking at a grid pattern? Metamorphopsia suggests macular pathology as the cause of diplopia 1

Age-Specific Considerations

Elderly Patients (>60 years)

• Have you noticed drooping of your upper eyelid or deepening of the crease above your eye? In elderly patients with horizontal diplopia worse at distance, this suggests sagging eye syndrome from age-related degeneration of connective tissue bands 5
• Have you had any recent vision changes or eye surgeries, including cataract surgery? Monovision correction or refractive surgery can unmask latent strabismus 1

Common Pitfalls to Avoid

Do not assume benign positional vertigo (BPPV) when double vision is present—BPPV does not cause diplopia, and coexisting diplopia with dizziness suggests central pathology requiring neuroimaging. 6

Do not rely solely on CT imaging for posterior fossa evaluation—MRI is superior for detecting brainstem lesions, demyelinating plaques, and posterior circulation pathology. 6, 5

Do not dismiss diplopia in patients with known macular disease as purely retinal—a proportion of these patients have other treatable forms of strabismus that require full orthoptic examination. 1