What it means and why
Diplopia means seeing two images of one object. It may persist in one eye alone, or occur because the two eyes’ images are not aligned. The distinction helps a clinician investigate possible causes; it does not itself identify a treatment.
Describe when it began, whether it is constant, the viewing distance and whether closing either eye changes it. This history is more useful than simply calling all ghosting “astigmatism”.
A worked example
Teaching scenario: double vision disappears when either eye is covered. Tell the clinician that observation rather than ordering prism. New sudden double vision or double vision with eye pain needs urgent assessment; severe headache, pupil change or head injury requires emergency care.
What it does not tell you
Blur and double vision are not interchangeable descriptions. Do not test your driving ability with new double vision; obtain assessment and follow local clinical guidance.
THINK IT THROUGHDoes double vision automatically mean a prism prescription is needed?
No. Treatment depends on the cause, and prism is only one possible clinical option.
Sources & reading notes
Page updated:
- NHS · Double vision ↗ Public health information
Useful for general health explanations and safety guidance; individual assessment and local advice still matter.