Diplopie

Diplopie, or diplopia, is the perception of two images of a single object. It can occur in one eye (monocular diplopia) or only when both eyes are open (binocular diplopia). Monocular diplopia persists when the affected eye is viewed with the other eye covered and is usually due to refractive error, cataract, corneal irregularity, or dry eye. Binocular diplopia disappears when either eye is closed and results from misalignment of the eyes caused by weakness or dysfunction of the extraocular muscles or the nerves that control them, or by disorders that affect eye alignment such as thyroid eye disease, myasthenia gravis, or orbital pathology.

Symptoms vary by cause. Diplopia can be horizontal, vertical, or diagonal, may be constant or intermittent, and can change with gaze, fatigue, or head position. Associated symptoms may include blurred vision, eye strain, ptosis, or headache. Acute onset with neurologic signs requires urgent evaluation to exclude dangerous conditions such as stroke or aneurysm.

Diagnosis involves a focused eye examination. Visual acuity, cover and alternate cover tests, and refraction help distinguish monocular from binocular diplopia. When binocular diplopia is suspected, assessment for nerve palsies, misalignment, neuromuscular disorders, and thyroid disease is undertaken. Neuroimaging (MRI or CT) is considered if intracranial or vascular causes are suspected. Blood tests may aid in identifying myasthenia gravis or thyroid disease.

Management depends on the cause. Monocular diplopia is typically addressed by correcting refractive error or removing media opacities. Binocular diplopia is treated by addressing the underlying condition, with temporary prism use, patching, or surgical realignment in selected cases. Many conditions improve over time, but persistent diplopia warrants specialist referral for comprehensive evaluation and individualized treatment.