Double Vision (Diplopia): Causes, Types and When It Is an Emergency
Quick answer: Double vision (diplopia) means seeing two images of one object. If it disappears when you cover either eye, it is binocular and comes from the eyes not lining up, which can be caused by nerve, muscle, thyroid or brain problems. If it stays with one eye covered, it is monocular and usually comes from the eye itself, such as astigmatism, dry eye or cataract. New double vision needs prompt assessment, and sudden double vision with headache, droopy lid, weakness or speech problems is an emergency.
Noticed this in your own eyes? Book an eye examination (NPR 400) with an optometrist at Vision Concern Lazimpat, Boudha-Tushal or Makalbari. WhatsApp +977 9841466716.
Related service: Comprehensive eye examination (NPR 400) at Vision Concern Lazimpat, Boudha-Tushal and Makalbari.
The cover test: one eye or both?
Cover one eye, then the other. If the double image goes away when either eye is covered, the problem is alignment between the two eyes (binocular diplopia). If one eye on its own still sees double or a ghost image, the cause is in that eye (monocular diplopia).
Common causes
- Monocular: uncorrected astigmatism, keratoconus, dry eye, cataract, lens or corneal irregularity
- Binocular: decompensated phoria or squint, cranial nerve palsy, thyroid eye disease, myasthenia gravis, orbital injury
- Serious causes: stroke, aneurysm, raised pressure in the skull
How it is assessed
An eye examination checks vision in each eye, the prescription, eye alignment in different directions of gaze and the front and back of the eye. Prism measurements show how far the eyes are out of line. Depending on the findings, you may be referred to an ophthalmologist or neurologist, and some people are helped by glasses with prism.
When to get urgent care
Call emergency services or go to an emergency department immediately if double vision is sudden and comes with headache, a droopy eyelid, a large pupil, weakness, numbness, facial droop, trouble speaking or swallowing, dizziness or a recent head injury.
How Vision Concern can help
Vision Concern optometrists in Kathmandu can examine your eyes, record what they find for comparison, update your glasses or contact lenses, and refer you to an ophthalmologist or eye hospital when medical treatment is needed. Vision Concern does not perform surgery or injections.
Frequently asked questions
Can tiredness cause double vision?
Fatigue can make a hidden eye misalignment break down and cause intermittent double vision, but new double vision should still be checked.
Can glasses fix double vision?
Monocular blur from astigmatism is often fixed with the right prescription. Some binocular double vision can be helped with prism glasses after assessment.
Is double vision always serious?
No, but it can be a sign of a serious condition, so any new double vision needs prompt assessment.
This guide is general information from the Vision Concern editorial team. It is not a diagnosis and does not replace an eye examination or medical advice.
Yes. Many visitors, particularly from Bangladesh and West Bengal (Kolkata), come to Nepal for cataract, retina, or other eye surgery at a hospital and also want new glasses, a general eye exam, or contact lenses at the same time, before or after their procedure. Vision Concern is an optical and eye-examination clinic, not a surgical hospital, so we work alongside hospitals such as Tilganga: we are happy to see you for glasses, contact lenses, or a routine check-up either side of your surgical treatment elsewhere.
No conversion is needed. Eyeglass prescriptions from Germany, France, the UK, the USA, China, Russia, and almost every other country use the same international format, SPH (sphere), CYL (cylinder), and AXIS, measured in diopters. Our opticians read this directly, so you can bring your prescription paper, a photo of it on your phone, or simply your current glasses, and we will use the same values. If your prescription is more than a year or two old, we recommend a quick, free re-check before we make your new pair.
Yes. Above roughly 3,000 metres, UV exposure increases sharply because of the thinner atmosphere and reflection off snow, and ordinary sunglasses (category 2-3) do not block enough UV to prevent snow blindness (photokeratitis). We recommend glacier glasses or category-4 sunglasses with side shields, and can fit these with your own prescription if needed. Vision Concern offers ZEISS polarized, UV400-certified sunglasses with prescription lenses, which we can prepare before you set off on your trek.