Yes, often. LASIK can remove the power from your glasses, but it cannot straighten your eyes, so you may still need prism glasses afterwards.
The good news: if your prism comes from thick lenses or from very different powers in your two eyes, LASIK can reduce it or remove it. The catch: if it treats a true squint or drift, it stays, and surgery can sometimes bring a hidden misalignment to the surface. That is why the first step is a proper alignment check, not a laser date.
Key Takeaways
- LASIK reshapes the cornea to focus light. Prism bends light to line up the two eyes. They solve different problems.
- Small, stable prism with a correctable prescription is often compatible with LASIK.
- Some prism is caused by your glasses. Thick lenses worn off-centre, or very different powers in each eye, create prism that can shrink or vanish after LASIK.
- Double vision, changing prism or a wish for monovision means an alignment check comes before any laser plan.
Is Your Prism Real, or Coming From Your Glasses?
One prism dioptre shifts what you see by 1 cm at a distance of 1 metre. Doctors prescribe it for squint, eye-muscle and nerve problems, thyroid eye disease and nystagmus. But not all prism starts as a prescription.
A strong lens acts like a prism when you look through it away from its centre. Prentice’s rule sizes it: lens power multiplied by the off-centre distance in millimetres, divided by 10. Looking 5 mm off the centre of an −8.00 D lens gives you 4 prism dioptres you never asked for.
| Type of prism | Where it comes from | Does LASIK change it? |
|---|---|---|
| Prescribed prism | Eyes that don’t line up | No. LASIK doesn’t move the eyes. |
| Prism induced by thick glasses | Looking off-centre through a high-power lens | It goes once you stop wearing that lens. |
| Prism from an off-centre laser treatment | Rare error; one reported case showed a large vertical prism | A complication, not a treatment. |
Sources: Prism correction (Wikipedia); Healio.
That is why the first step is measuring your eyes without the glasses, not reading the prescription slip.
What Kind of Misalignment Do You Have?
A phoria is a hidden drift that shows only when one eye is covered. A tropia is a squint you can see with both eyes open. The cause behind your prism changes the LASIK answer.
| Your condition | What it means for LASIK | What to do |
|---|---|---|
| Small phoria, steady for months | ✅ LASIK usually still improves your focus | Ask for a cover test |
| Prism added because your two eyes have very different powers (anisometropia) | ✅ LASIK treats the cause, so you may need less prism or none | Ask to have this tested |
| Far-sighted, well-controlled inward turn (accommodative esotropia) | ✅ May actually benefit: in one strabismus specialist’s review, 58% improved after refractive surgery | See a squint specialist first |
| Constant squint (tropia) | ⚠️ LASIK fixes focus only; the eyes stay crossed | Discuss squint surgery as well |
| Nerve palsy, thyroid eye disease or recent double vision | ⚠️ Prism needs can rise or fall over time, so results are hard to predict | Wait until readings are steady |
Sources: Merck Manual; Review of Ophthalmology (2004); CRSToday (2003); Insight Vision.
Why can glasses create prism at all? Ophthalmologists writing in Review of Ophthalmology note that correcting a power gap above 2 dioptres with spectacles creates a prismatic imbalance that interferes with reading, especially when it is vertical, and that even a small size difference between the two eyes’ images can cause headaches, dizziness and poor depth perception. Fixing the gap at the cornea removes that source. Our pages on crossed eyes and lazy eye cover these conditions in more detail.
Can LASIK Work for Your Situation?
| Your situation | What it means | What to do |
|---|---|---|
| Prism or prescription changed in the past year | ⚠️ Your eyes haven’t settled | Wait and recheck; see how stable your prescription must be |
| Far-sighted, high myopia, very different power in each eye, or over 40 | ⚠️ Named as risk factors in the studies below | Ask for extra alignment testing |
| You want one eye set for reading (monovision) | ⚠️ A focus gap above about 1.25 D can’t be fused, and can unmask a hidden squint | Trial it in contacts; see monovision pros and cons |
| Double vision that comes and goes, or you close one eye to see clearly | ❌ LASIK won’t fix it and may make it more obvious | Get a squint assessment first |
| Sudden double vision with headache, drooping eyelid or weakness | ❌ A medical problem, not a focusing one | Seek urgent care |
Sources: Archivos de la Sociedad Española de Oftalmología; CRSToday (2003); Healio.
Why Alignment Problems Can Show Up After LASIK?
Many people hold their eyes straight by effort, and blur can hide the strain. When vision turns sharp or a prescription shifts, that effort may not hold. EyeWiki calls decompensation of an existing squint the most common cause of binocular double vision after LASIK.
In one Spanish centre’s series of 4,135 refractive procedures, 19 patients developed binocular problems, all with an earlier binocular problem. Eleven drifted inward, 10 were over 40, and causes often overlapped: leftover far-sightedness, a big power gap between the eyes and a change in eye dominance.
The reassuring part: EyeWiki says most cases are corrected with prism glasses or squint surgery, and that prevention starts with a thorough history and eye-movement exam. If you ever had a squint, patching or eye exercises as a child, say so at your first visit.
What Changes in the First Months?
Even people with straight eyes see a temporary shift. In a study of 61 short-sighted patients with normal alignment, the link between focusing and eye turning (the AC/A ratio) fell at 1 week and 1 month after LASIK, then recovered towards its old value between 3 and 9 months. Symptoms dropped from the first month onwards.
| When | What the study found | What it means for you |
|---|---|---|
| 1 week to 1 month | AC/A ratio significantly lower | Near work may feel different; report double vision early |
| Month 1 onwards | Fewer patients had symptoms | Many settle without treatment |
| 3 to 9 months | Ratio recovered towards pre-op values | Ask when to re-measure before ordering new prism glasses |
Source: Journal of Cataract & Refractive Surgery (61 patients).
What Tests Should You Expect?
| Test | What it shows | Why it matters |
|---|---|---|
| Cover test, distance and near | How far each eye drifts when fusion is broken | Confirms the type and size of misalignment |
| Stereo test at near | Whether both eyes work as a team (see depth perception) | Shows how much fusion you could lose |
| Patching one eye for about 30 minutes | A deviation hidden by effort | Reveals a latent squint before surgery does |
| Contact-lens trial | How your eyes cope with the planned focus | Advised for 2 weeks to a month for monovision, not minutes in the chair |
| Old vs new prism readings | Whether your prism is stable | Steady readings make results more predictable |
Sources: CRSToday (2003); Visual Aids Centre.
Our LASIK candidacy guide covers the other eligibility checks, from corneal thickness to tear film.
Squint Surgery or LASIK First?
If you may need both, the order matters. A strabismus specialist writing in Cataract & Refractive Surgery Today advised doing refractive surgery first in almost all cases, because it can change the angle of your deviation. Some clinics, such as London Vision Clinic, also combine laser with muscle surgery. Ask which your surgeon prefers and why. For squint surgery itself, see the squint surgery success rate.
What Happens to Your Prism Glasses Afterwards?
If your alignment needs prism, expect to keep it. What changes is the lens power: glasses can carry prism with little or no power. See how zero power glasses work after LASIK.
- Prism contact lenses: the American Academy of Ophthalmology says prism can nearly never be built into contacts. Don’t plan around it.
- New prism glasses: expect floors to look slanted at first; most people adapt within days to a few weeks.
- Non-surgical options: vision therapy helps some milder problems; see squint treatment without surgery.
- Growing deviation: if prism stops working, the AAO notes surgery may bring the eyes back into a range where prism helps again. Read about double vision after squint surgery.
- Strain after LASIK: these tips help, but persistent doubling needs an alignment review.
What to Ask Your Surgeon?
- Is my prism prescribed, or coming from my glasses?
- Has it stayed the same, and how do you know?
- Will you run a cover test, including with my eye patched?
- Should I avoid monovision?
- How will my treatment be centred? Off-centre lasers are rare, but one reported case created a large vertical prism. See topography-guided vs wavefront LASIK.
- Which specialist sees me if double vision appears?
Living with involuntary eye movement too? Read about LASIK with nystagmus.
Bottom Line
LASIK may free you from thick lenses, but it will not straighten your eyes. Small, steady prism with a correctable prescription is often workable. Changing prism, intermittent double vision or monovision plans need an alignment check first. Book a consultation at Visual Aids Centre and bring your latest glasses prescription and any earlier squint or eye-muscle records.
FAQs
Can LASIK remove my prism?
No. LASIK changes focus, not alignment. Only prism caused by off-centre thick glasses goes, because you stop wearing those lenses.
Will I still need prism glasses after LASIK?
If your eyes are misaligned, usually yes, but the glasses can carry little or no power.
Is LASIK unsafe if I need prism?
Not automatically. The risk is a hidden or unstable misalignment coming to light, which pre-op testing is designed to catch.
How stable should my prism be?
Your surgeon wants readings that haven’t changed over time. Many clinics look for at least 6 months, so ask what yours requires.
Can LASIK reduce the prism I need?
Sometimes. If the prism was added because your two eyes have very different powers, correcting that gap may reduce it. Prism for a true misalignment stays.
Can prism go into contact lenses?
Almost never, according to the American Academy of Ophthalmology.
Should squint surgery come before LASIK?
One specialist review advises LASIK first in almost all cases, but the order is your surgeons’ call.
Can LASIK cause double vision?
Rarely. In one Spanish series, 19 of 4,135 refractive procedures led to binocular problems, all in patients with an earlier binocular problem.
