Diplopia (Double Vision)

Diplopia refers to the perception of seeing two images of a single object and may have both ophthalmologic and neurologic origins. The condition can manifest as horizontal (side-by-side), vertical (over-under), or mixed double vision. Diplopia often affects balance, coordination, and reading ability, making it a critical symptom that requires thorough assessment.

Types and Presentation

Monocular Diplopia

• Occurs when only one eye is affected.

• The double vision persists when the healthy eye is covered but disappears when the affected eye is covered.

• Typically caused by intraocular pathologies such as refractive errors, cataracts, corneal disease, or macular disease.

Binocular Diplopia

• Appears when both eyes are open and resolves when one eye is covered.

• Most often caused by extraocular muscle dysfunction or cranial nerve palsy, resulting in ocular misalignment.

• The image of an object falls on the fovea of one eye and an extrafoveal area of the other, producing double vision.

Causes

Monocular Diplopia

• Refractive errors

• Cataract

• Corneal disease (e.g., irregular astigmatism)

• Macular degeneration or macular pathology

• Lens displacement (e.g., luxation)

• Psychogenic causes or dry eye syndrome

Binocular Diplopia

Neurological causes (most common):

• Cranial nerve palsies (CN III, IV, VI)

  • Oculomotor nerve palsy: affects superior, medial, and inferior rectus, and inferior oblique muscles

  • Trochlear nerve palsy: affects superior oblique muscle

  • Abducens nerve palsy: affects lateral rectus muscle

Other causes:

• Thyroid eye disease

• Aneurysm

• Diabetes mellitus

• Brain or orbital tumor

• Multiple sclerosis

• Head trauma

Evaluation

A careful history and clinical examination are essential to distinguish between ocular pathology, cranial nerve lesions, and neuromuscular disorders.

• Acute-onset diplopia may signal a serious underlying disorder.

• Intermittent diplopia with ptosis and daily variation suggests myasthenia gravis.

• Progressive diplopia may indicate tumor or aneurysm compression.

Monocular Diplopia

• Ophthalmologic evaluation focusing on cornea, lens, and retina.

• Pinhole test helps differentiate refractive errors from organic pathology.

Binocular Diplopia

• Assess ocular alignment and identify potential extraocular muscle paresis.

Physiotherapy Examination

Observation

• Inspect for redness, swelling, or discharge.

• Ask the patient to look upward without moving the head to observe range of motion.

Tests

• Red reflex test: Ophthalmoscope used to assess posterior eye segments.

• Light reflex test: Evaluates corneal reflection symmetry.

• Accommodation test: Focus shift between near and far targets.

• Visual acuity: Snellen chart or finger counting.

• Ocular motility test: Evaluate all gaze directions with head stable.

• Cover test: Patient covers one eye and reports persistence of double vision.

Saccades and Pursuits

• Saccades: Rapid eye movements controlled by the frontal eye field (Brodmann area 8).

• Pursuits: Smooth tracking movements controlled by the parietal–occipital–temporal cortex.

Treatment

Medical Management

• Depends on underlying cause:

  • Prismatic lenses to correct alignment

  • Surgical correction for muscle or nerve lesions

  • Medication for autoimmune or inflammatory causes

Physiotherapy Management

• Eye muscle exercises, saccades, and pursuit training can aid recovery and coordination.

Saccade Exercises

• Focus on points on a page for 1 second, then jump to the next.

• Perform horizontally, vertically, and diagonally.

• 3–5 rounds, 3–4 times daily.

Pursuit Exercises

• Follow the thumb or a pen horizontally, vertically, and diagonally.

• Gradually increase movement speed.

Summary

Diplopia is a clinically important symptom that may range from minor refractive errors to severe neurological conditions. Accurate diagnosis requires detailed history-taking, ocular examination, and neurological assessment. Physiotherapy plays a supportive role through observation, visual tests, and oculomotor training, while medical interventions target the underlying cause.

References

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2. Rucker JC, Tomsak RL. Binocular diplopia: a practical approach. The neurologist. 2005 Mar 1;11(2):98-110.

3. Gjenomgått -Trukket

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7. Merino P, Fuentes D, de Liaño PG, Ordonez MA. Binocular diplopia in a tertiary hospital: aetiology, diagnosis, and treatment. Archivos de la Sociedad Española de Oftalmología (English Edition). 2017 Dec 1;92(12):565-70.

8. Dinkin M. Diagnostic approach to diplopia. continuum: Lifelong Learning in Neurology. 2014 Aug 1;20(4):942-65.