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LASIK prescription limits: how high is too high? (2026)

What prescription is too high for LASIK?

There is no single cut-off. Depending on the excimer laser, LASIK can treat up to about −12.00 D of myopia, +6.00 D of hyperopia and 6.00 D of astigmatism, but many surgeons stop well short of those maximums because your cornea, not the device label, usually sets the real limit.

The American Academy of Ophthalmology (AAO) lists extreme nearsightedness, farsightedness or astigmatism among the reasons not to have LASIK. Where the line falls for you depends on corneal thickness, corneal shape, pupil size and eye health, which are measured at a full pre-op eye exam. The ranges on this page were checked on 1 November 2026.

What are the treatment ranges for LASIK, SMILE and ICL?

Each procedure has a different range. The table shows published US ranges from device makers and regulators. Ranges approved in Korea and other countries can differ by device, so ask your clinic which laser or lens it uses.

In 2026 the US FDA widened the EVO ICL age indication from 21–45 to 21–60. The US label also requires an anterior chamber depth of at least 3.00 mm, which your exam will measure.

Why does corneal thickness matter more than the number?

LASIK and SMILE work by removing corneal tissue, and higher prescriptions need more tissue removed. Enough untouched cornea must remain afterwards to keep the eye strong. The FDA warns that reshaping a cornea that is too thin may result in blinding complications, because a weakened cornea can bulge (ectasia).

That is why two people with the same prescription can get different answers. A patient with −7.00 D and a thin cornea may be told no to LASIK, while a patient with −9.00 D and a thick, regular cornea may be accepted. Read more in corneal thickness for LASIK.

Other factors also narrow the range:

• Corneal shape: tomography screens for keratoconus, which rules out LASIK
• Pupil size: the FDA notes large pupils in dim light can cause glare and halos after surgery
• Dry eye: severe dry eye is on the AAO list of reasons not to have LASIK
• Stability: the FDA says a change in glasses or contact lens prescription in the past year may make you a poor candidate

What are my options above the LASIK limit?

You usually still have options. The right one depends on your prescription, cornea and age:

• SMILE, or SMILE Pro on the VisuMax 800, for myopia within its range, without a flap
• ICL, a lens placed inside the eye with no corneal tissue removed, for high myopia or thin corneas
• LASEK or PRK, surface treatments that leave more corneal strength at moderate prescriptions
• Refractive lens exchange, usually for people over about 45 or with high hyperopia

Compare them in ICL vs LASIK and options for high myopia.

How does astigmatism change the limit?

Astigmatism adds to the treatment, so a high sphere plus high cylinder can push you past what your cornea allows even if each number alone looks fine. SMILE's US range stops at 3.00 D of astigmatism, while toric ICLs correct 1.00 to 4.00 D in the US label and LASIK lasers go higher. Irregular astigmatism from keratoconus is different and is not treated with LASIK. See LASIK with astigmatism and toric ICL in Korea.

How do I read my own prescription?

Your glasses prescription has three parts: sphere (SPH), cylinder (CYL) and axis. Surgeons often talk about the spherical equivalent, which is the sphere plus half the cylinder.

These are illustrations, not advice. Only your measurements can say what is safe for your eyes.

Does my prescription need to be stable first?

Yes. The FDA flags any change in the past year, ZEISS asks for no more than 0.50 D change in the year before SMILE, and the EVO ICL US label asks for refraction stable within 0.50 D for one year. Bring old prescriptions to your exam so the surgeon can see the trend; see LASIK age limit.

How much more does it cost if I need ICL instead?

A higher prescription can change the procedure and the price. Seoul ranges checked in 2026, for both eyes: LASIK ₩1.5M–₩2.5M (approximately $1,100–$1,900), SMILE ₩2.2M–₩3.2M and ICL or EVO ICL ₩4M–₩6.5M (approximately $2,900–$4,700). See cost of LASIK in Korea and cost of ICL in Korea.

This page is general information. Your surgeon decides whether any procedure is safe for you after a full exam.

Sources

• AAO – LASIK: Laser Eye Surgery
• FDA – When is LASIK not for me?
• American Refractive Surgery Council – LASIK prescription requirements and limits
• ZEISS – Is ZEISS SMILE right for me?
• STAAR Surgical – US FDA approval of EVO Visian ICL
• Healio – FDA expands age indication for EVO ICL

FAQ

Frequently asked questions

Is −8 too high for LASIK?

Not necessarily. −8.00 D is within the range many lasers can treat, but whether it is safe depends on your corneal thickness and shape. Some people at −8.00 D are better suited to SMILE or ICL.

Can you get LASIK with a −10 prescription?

Some people can, if their cornea is thick and regular, but many surgeons recommend ICL at this level because it removes no corneal tissue. Ask the surgeon to explain the residual corneal thickness LASIK would leave.

What is the maximum prescription for SMILE?

In the US, ZEISS lists −1.00 to −10.00 D of myopia with 0.75 to 3.00 D of astigmatism. Ranges in other countries can differ, so ask your clinic which range applies to its laser.

Can LASIK fix farsightedness?

Yes, within limits: lasers treat up to about +6.00 D depending on the device. Higher hyperopia, or hyperopia after about 45, is often better treated with a lens procedure.

Is ICL better than LASIK for high myopia?

For high myopia, ICL often gives a wider safety margin because the cornea is left intact. It is a surgery inside the eye with its own risks, so compare both with your surgeon.

Planning vision correction in Seoul?

Compare clinics by district, check 2026 price ranges, and read our step-by-step planning guide for international patients.