Double vision, or diplopia, occurs when two separate images are perceived instead of one. It can be monocular (persisting when one eye is covered) or binocular (present only with both eyes open).
Mechanisms
Monocular diplopia is usually due to optical issues such as cataract, corneal irregularity or high astigmatism. Binocular double vision typically results from misalignment of the eyes caused by muscle imbalance, cranial nerve palsies or neurological disease.
- New-onset double vision requires prompt assessment
- Associated ptosis, headache or imbalance may indicate neurological causes
- Management options include prisms, occlusion or strabismus surgery
- Systemic investigations may be necessary when vascular or inflammatory disease is suspected
