Specialty Vision · Vision Simulator
Double Vision & Eye-Teaming Simulator
Double vision (diplopia) means seeing two overlapping images of one object — usually because the two eyes aren't aiming at the same point, from a muscle imbalance (strabismus) or trouble focusing together up close.
When your eyes don't team up
Your two eyes normally point at the same spot, and the brain fuses their images into one. When they don't aim together — from a muscle imbalance (strabismus) or trouble converging up close — you can see double, overlapping or 'ghosted' images, often with strain and fatigue. Pick a type below to see how it can look.
Overview
Normally the two eyes point at the same target and the brain fuses their two views into a single 3-D image. When the eyes are misaligned — constantly (strabismus) or only under strain (convergence insufficiency) — the brain receives two offset images and you see double, ghosted or overlapping. Double vision in one eye only, which does not disappear when the other eye is covered, points instead to a problem within that eye, such as astigmatism, cataract or dry eye.
Symptoms of double vision
- Seeing two overlapping or side-by-side images of a single object
- Eye strain, fatigue or headaches, especially after reading or screen work
- Words that run together, swim or double when reading up close
- Tilting or turning the head, or closing one eye, to see clearly
- In children: an eye that visibly turns in, out, up or down
What causes double vision
- Strabismus — an imbalance in the eye muscles that misaligns the eyes
- Convergence insufficiency — difficulty turning the eyes inward to focus up close
- Nerve problems affecting eye-movement control (sometimes from diabetes, stroke or injury)
- Monocular double vision (in one eye) from astigmatism, cataract, dry eye or keratoconus
Double vision risk factors
- Family history of strabismus
- Uncorrected refractive error in childhood
- Diabetes, high blood pressure or stroke (nerve-related causes)
- Head injury or certain neurological conditions
Prevention & early detection
- Many causes can't be prevented, but children's eye-alignment problems are most treatable when caught early — keep routine children's eye exams
- Manage diabetes and blood pressure to lower the risk of nerve-related double vision
- Take regular breaks from sustained near work to ease eye strain
Treatment
Treatment targets the cause. Glasses (sometimes with a prism), vision therapy and eye exercises (especially effective for convergence insufficiency), patching, or eye-muscle surgery can realign the eyes or restore comfortable single vision. Double vision in one eye is treated by addressing its source — for example correcting astigmatism or removing a cataract. New, sudden double vision needs prompt evaluation to rule out a serious nerve cause.
When to see an eye doctor
Long-standing, mild eye strain can be assessed at a routine exam, but new or sudden double vision should be checked promptly — and urgently if it comes with a severe headache, a droopy eyelid, weakness, slurred speech or eye pain, which can signal a nerve or brain problem. In children, any eye that consistently turns should be examined early to protect developing vision.
Seek urgent care for:
- Sudden, new double vision
- Double vision with a severe headache, a droopy eyelid or eye pain
- Double vision with weakness, numbness or slurred speech
- A child's eye that constantly turns in, out, up or down
Frequently asked questions
Why do I see double?
Most often because your two eyes aren't aiming at exactly the same point, so the brain gets two offset images. If covering one eye makes the doubling disappear, it is 'binocular' (an alignment problem); if it persists in one eye alone, the cause is within that eye, such as astigmatism or a cataract.
Can double vision be fixed?
Usually, yes — by treating the cause. Options include glasses or prisms, vision therapy (very effective for convergence problems), patching, or eye-muscle surgery for strabismus. Single-eye double vision is fixed by addressing its source.
Is double vision serious?
It can be. Long-standing mild strain is usually benign, but sudden double vision — especially with headache, a droopy lid, weakness or slurred speech — can signal a nerve or brain problem and needs urgent care.
What is convergence insufficiency?
It is difficulty turning the eyes inward together to focus on near objects, so reading becomes tiring and text blurs or doubles. It is common, often missed, and responds well to vision therapy.
Sources
- What Is Strabismus? — American Academy of Ophthalmology
- Convergence Insufficiency — American Academy of Ophthalmology