What is the recommended evaluation and management for a patient presenting with new‑onset diplopia?

Management of New-Onset Diplopia

All patients with new-onset diplopia require urgent evaluation with a complete sensorimotor examination and immediate neuroimaging (MRI brain with gadolinium plus MRA or CTA) if any pupil involvement, multiple cranial nerve palsies, or associated neurological symptoms are present. 1

Immediate Red Flags Requiring Emergency Imaging

• Any pupil-involving third nerve palsy (anisocoria with ptosis and ophthalmoplegia) is a neurosurgical emergency requiring immediate MRA or CTA to exclude posterior communicating artery aneurysm; if negative but suspicion remains high, proceed to catheter angiography after contrast-enhanced brain MRI 1
• Even mild pupil involvement in a vasculopathic-appearing third nerve palsy cannot exclude compressive pathology and mandates imaging 1
• Bilateral sixth nerve palsy signals serious pathology including clival chordoma, elevated intracranial pressure, or meningeal disease 1
• Patients over 60 years with scalp/temporal tenderness or jaw claudication require immediate ESR/CRP to exclude giant cell arteritis, which can cause irreversible vision loss 1
• Vision loss accompanying diplopia raises concern for concurrent optic neuropathy or retinal artery occlusion; these patients have 3-6% risk of ischemic stroke within 1-4 weeks and require urgent emergency department or stroke center referral 1

Essential History Components

• Onset pattern: Sudden onset suggests vascular, aneurysmal, or traumatic causes; gradual onset suggests compressive lesions, thyroid eye disease, or neoplasm 1, 2
• Diplopia characteristics: Horizontal diplopia worsening with distance suggests sixth nerve palsy; vertical or torsional diplopia points toward fourth nerve palsy or skew deviation 1
• Associated symptoms: Ptosis indicates third nerve involvement; headache, neck pain, or compensatory head position may indicate superior oblique palsy or other cranial nerve dysfunction 2, 1
• Vascular risk factors: Diabetes, hypertension, hyperlipidemia favor microvascular ischemic palsy, which typically resolves within six months 1
• Trauma history: Even occult fractures can present with strabismus without recalled trauma 1

Comprehensive Examination Protocol

Visual and Pupillary Assessment

• Document visual acuity with current correction; high hyperopia or anisometropia may contribute to decompensated strabismus 2
• Assess pupils for anisocoria, relative afferent pupillary defect, and accommodation deficit 1
• Perform cycloplegic refraction to identify latent refractive error that might improve alignment 2

Motility Examination

• Complete cover-uncover and alternate cover testing in all positions of gaze 2
• Test binocular fusion and stereopsis 2
• Evaluate ductions (each eye separately) and versions (both eyes together) to identify restriction versus paresis 1
• For suspected fourth nerve palsy, perform Parks-Bielschowsky three-step test: hypertropia is greatest in opposite lateral gaze and head tilt to the same side 2
• Assess ocular torsion by sensory testing (Double Maddox Rod or Lancaster Red-Green) or fundus examination, particularly in vertical strabismus 2

Additional Examination Elements

• Inspect for proptosis or inflammatory changes suggesting thyroid eye disease, orbital pathology, or cavernous sinus involvement 2
• Examine for conjunctival scars or exposed thinned sclera indicating prior extraocular muscle surgery 2
• Assess interpalpebral fissures for evidence of prior muscle resection (smaller fissure) or recession (larger fissure) 2

Neuroimaging Strategy

• Preferred initial study: MRI brain with and without gadolinium plus MRA or CTA for all cranial nerve palsies, especially third nerve palsy 1
• If MRI unavailable, obtain immediate CT/CTA for pupil-involving third nerve palsy; if negative but clinical suspicion remains high, proceed to catheter angiography 1
• Unenhanced CT of the head or orbits is not useful in diplopia workup 1
• Orbital imaging (CT, MRI, or ultrasound) may aid in localizing previously operated extraocular muscles, though most cases can be managed without imaging using careful clinical assessment 2

Etiology-Specific Management

Microvascular Ischemic Palsy

• Occurs in patients with diabetes, hypertension, or hyperlipidemia; onset is acute and may be painful 1
• Approximately one-third recover within eight weeks and most resolve by six months 1
• Critical pitfall: Lack of recovery at six months warrants comprehensive work-up because approximately 40% have serious underlying pathology 1
• Management focuses on optimizing vascular risk factors (glycemic control, blood pressure, lipid management) 1

Posterior Communicating Artery Aneurysm

• Requires immediate neurosurgical consultation; imaging and specialist referral must not be delayed 1

Giant Cell Arteritis

• Initiate high-dose corticosteroids immediately to prevent permanent vision loss 1
• ESR/CRP testing is essential in all patients over 60 years with recent diplopia 1

Superior Oblique Palsy

• Diplopia with compensatory head position (sometimes associated with neck pain) and asthenopia warrant treatment 2
• Quantify torsional diplopia magnitude and direction to enhance surgical planning 2
• Neuroimaging controversial but rarely indicated in isolated unilateral cases or bilateral cases with known trauma; always perform if additional CNS signs or symptoms present 2
• Consider occult thyroid eye disease, which can present as new-onset vertical diplopia with positive three-step test 2

Symptomatic Management While Awaiting Diagnosis or Recovery

Non-Surgical Options

• Immediate relief: Eye patching, occlusive contact lenses, Bangerter foils, or MIN lenses 1
• Prism correction: Press-on Fresnel or ground-in prisms offer temporary improvement, though effectiveness is limited in incomitant deviations 2, 1
• Refractive management: Correct hyperopia with appropriate bifocal or progressive lenses for adults approaching presbyopia; reversal of monovision may resolve symptoms in some patients 2
• Botulinum toxin: Injection into antagonist extraocular muscle or levator can temporize symptoms pending recovery 1
• Patients with complete ptosis often do not notice diplopia until the lid is elevated; addressing ptosis may improve visual comfort 1
• Prescribe uni-ocular progressive lenses or high-segment bifocals when infraduction is compromised and accommodation deficits cause reading difficulty 1

Surgical Management

• For childhood-onset strabismus presenting in adults, correction is generally surgical, though specifics vary based on underlying condition 2
• Address sequelae of previous surgery (underaction of recessed muscle, restriction of scarred muscle, unsightly conjunctival scarring) to optimize alignment 2
• For superior oblique palsy, surgical options include inferior oblique weakening, inferior rectus weakening (contralateral), superior oblique strengthening (tuck for lax tendons, advancement for vertical/torsional deviations, or Harada-Ito procedure), or superior rectus weakening (ipsilateral) 2
• Many procedures may be performed using adjustable suture techniques 2

Disposition and Follow-Up

• Immediate ophthalmology/neurosurgery consultation: Pupil-involving third nerve palsy, signs of increased intracranial pressure, multiple cranial nerve palsies 1
• Urgent referral within one week: Isolated fourth or sixth nerve palsies without additional neurological signs 1
• Skew deviation: Refer to neurology, otolaryngology, or neuro-otology based on suspected underlying cause 1
• Six-month re-evaluation: If presumed microvascular palsy has not recovered, initiate comprehensive work-up for alternative etiologies 1
• Monitor/observe if symptoms are mild, occasional, and well tolerated or if patient is opposed to treatment 2

Critical Pitfalls to Avoid

• Do not assume pupil-sparing third nerve palsy is benign when ptosis is incomplete or muscle involvement is partial; imaging remains required 1
• Do not miss bilateral sixth nerve involvement, as it suggests serious pathology such as clival chordoma, increased intracranial pressure, or meningeal disease 1
• Do not forget ESR/CRP in patients over 60 years with diplopia to rule out giant cell arteritis 1
• Do not delay imaging in patients with pupil-involving third nerve palsy even if other diagnoses (such as prolactinoma) are suspected, as aneurysm must be excluded urgently 3
• Prism testing in adult strabismus originating in early childhood can be misleading due to anomalous retinal correspondence; patients often have diplopia with prism but rapidly adapt to surgical correction 2