Evaluation and Management of New Onset Monocular Double Vision
New onset monocular diplopia requires immediate comprehensive ophthalmologic evaluation to distinguish between benign optical causes (refractive errors, corneal irregularities, lens opacities) and potentially serious neurologic etiologies, with management directed at the specific underlying cause identified through systematic examination. 1, 2
Critical First Step: Confirm True Monocular Diplopia
The essential diagnostic maneuver is determining whether diplopia persists with occlusion of the unaffected eye 2, 3:
- If diplopia resolves with covering either eye: This is binocular diplopia requiring urgent neurologic evaluation for cranial nerve palsies, myasthenia gravis, or intracranial pathology 1, 4
- If diplopia persists with the affected eye alone: True monocular diplopia, typically indicating ocular pathology 2, 3
Systematic Evaluation Algorithm
History Components to Document
- Onset characteristics: Sudden versus gradual (sudden suggests trauma, corneal pathology; gradual suggests progressive lens changes) 1, 4
- Trauma history: Even minor or remote ocular trauma can cause corectopia or lens subluxation 1, 5
- Previous eye surgeries: Post-surgical corectopia is a recognized cause of monocular diplopia 5
- Associated symptoms: Headache with monocular diplopia may indicate idiopathic intracranial hypertension with papilledema 6
Essential Examination Elements
Perform these specific tests 1, 2:
- Visual acuity with pinhole: Improvement with pinhole strongly suggests refractive cause 5
- Cycloplegic refraction: Mandatory to identify uncorrected refractive errors, particularly high hyperopia or astigmatism 1
- Slit-lamp biomicroscopy: Examine for corneal irregularities (scars, keratoconus, dry eye), lens opacities (cataracts, subluxation), iris abnormalities (corectopia, polycoria) 2, 5
- Pupillary examination: Irregular or displaced pupils can create multiple apertures causing diplopia 5
- Dilated fundus examination: Rule out macular pathology and assess for papilledema if headache present 6
Common Pitfall to Avoid
Do not assume monocular diplopia is always benign. While most cases result from optical aberrations, monocular diplopia can be the presenting symptom of idiopathic intracranial hypertension with papilledema 6. Any patient with monocular diplopia accompanied by headache requires funduscopic examination and, if papilledema is present, urgent neuroimaging and lumbar puncture 6.
Treatment Based on Etiology
Refractive Causes
- Optimal spectacle correction: First-line for uncorrected refractive errors 2, 5
- Contact lens trial: May be superior to spectacles for irregular astigmatism 5
Corneal Irregularities
- Rigid gas permeable contact lenses: Mask irregular corneal surface 2
- Artificial tears: For dry eye-related surface irregularity 2
Pupillary Abnormalities (Corectopia, Polycoria)
- Prosthetic contact lens with artificial pupil: Blocks aberrant light pathways through irregular pupil 5
- Combined approach: Prosthetic contact lens plus spectacle correction may be necessary 5
Lens Opacities
- Cataract surgery: Definitive treatment when cataract is causative 2
Neurologic Causes (Idiopathic Intracranial Hypertension)
- CSF pressure reduction: Through lumbar puncture, acetazolamide, or surgical shunting resolves diplopia 6
Referral Pathways
Immediate ophthalmology referral indicated for 1, 2:
- Any monocular diplopia with headache (rule out papilledema)
- Post-traumatic monocular diplopia
- Progressive visual decline
- Failed conservative optical management
Neurology/neuro-ophthalmology referral if 6:
- Papilledema identified on funduscopy
- Suspected idiopathic intracranial hypertension
- Atypical features suggesting neurologic disease