If you’ve been told your “number is too high” for LASIK, you’re asking exactly the right question — but the answer isn’t as simple as a single number. The maximum eye power LASIK can correct depends on the type of procedure, your corneal thickness, and several individual factors that only a detailed pre-operative evaluation can determine.
This guide breaks down the actual dioptre limits for each type of refractive surgery available today, explains why corneal thickness matters more than your prescription number alone, and covers what alternatives exist if your power falls outside the LASIK range. Whether you have -6, -9, or -12, there’s a good chance a safe, effective option exists for you — you just need to know which one.
Key Takeaways
- Standard LASIK corrects up to approximately -8.0 D myopia, +5.0 D hyperopia, and up to 6.0 D astigmatism — but individual limits depend on corneal thickness.
- SMILE Pro extends the myopia range to around -10.0 D with less corneal tissue removal than LASIK.
- ICL (Implantable Collamer Lens) can correct up to -18.0 D or higher, making it the primary option for very high powers.
- Corneal thickness — not just your prescription — is the true limiting factor for any laser-based procedure.
Maximum Eye Power Limits by Procedure Type
Different laser platforms and surgical techniques can safely correct different ranges of refractive error. Here’s how the main procedures compare.
Femto LASIK and Contoura Vision
Standard Contoura Vision and Femto LASIK can safely correct myopia (minus power) up to approximately -8.0 dioptres and hyperopia (plus power) up to +5.0 dioptres. In practice, the exact upper limit varies from patient to patient because the laser must remove more corneal tissue as the power increases. A person with -8.0 and thick corneas may be an excellent candidate, while someone with -6.0 and thin corneas may not qualify at all.
SMILE Pro
SMILE Pro can treat myopia up to approximately -10.0 dioptres. Because SMILE removes a lenticule of tissue through a small keyhole incision rather than creating a full corneal flap, it preserves more structural integrity in the cornea. This makes it a better option for patients at the higher end of the treatable range — particularly those with moderate corneal thickness who fall just outside LASIK eligibility.
ICL (Implantable Collamer Lens)
For patients whose power exceeds what any laser procedure can safely correct, ICL is the gold-standard alternative. ICL can correct myopia from -3.0 all the way up to -18.0 dioptres (and sometimes beyond), plus up to 6.0 dioptres of astigmatism. Because ICL is implanted inside the eye rather than reshaping the cornea, it doesn’t remove any corneal tissue — making it ideal for patients with thin corneas or very high prescriptions.
TransPRK
TransPRK is a surface ablation technique that avoids creating a corneal flap entirely. It treats myopia up to approximately -8.0 D, similar to LASIK, but is often preferred for patients with borderline corneal thickness or those in professions where flap-related risks are a concern.
Why Corneal Thickness Is the Real Limiting Factor
Your prescription number tells part of the story, but corneal thickness tells the rest. Every dioptre of myopia correction requires removing roughly 12–16 microns of corneal tissue. A safe LASIK procedure must leave a residual stromal bed of at least 250 microns (many surgeons prefer 300 or more) to prevent structural weakening that could lead to post-LASIK ectasia — a serious complication where the cornea progressively bulges outward.
The average Indian cornea measures around 530 microns. Once you subtract the flap thickness (typically 100–110 microns for femtosecond flaps) and the required safety margin, the remaining tissue available for ablation determines your actual treatable range. This is why a thorough Pentacam scan and corneal topography are essential pre-operative steps — your surgeon calculates whether your specific cornea can safely accommodate the correction you need.
For context: a patient with 560-micron corneas and -9.0 D myopia might be a safe LASIK candidate, while a patient with 490-micron corneas and -5.0 D myopia might not. The number alone never decides eligibility — the calculation does.
Astigmatism (Cylindrical Power) Limits
Astigmatism correction follows its own set of limits. LASIK and Contoura Vision can typically correct up to 6.0 dioptres of cylindrical power, though topography-guided platforms like Wavelight Plus (Innoveyes) may handle irregular astigmatism patterns more precisely than standard treatments. SMILE Pro addresses astigmatism up to about 5.0 D, while ICL with toric correction covers up to 6.0 D.
When astigmatism exists alongside significant myopia or hyperopia, the combined correction demands more tissue removal, which can push borderline cases out of the laser-safe range. Your surgeon evaluates the total correction required — spherical plus cylindrical — not just one number in isolation. For more on this topic, see how to reduce cylindrical power.
What If Your Power Is Too High for LASIK?
Being told you’re “not a candidate for LASIK” doesn’t mean you’re out of options. It means LASIK specifically isn’t safe for your eyes — but several excellent alternatives exist.
ICL is the most common pathway for high-power patients. It’s reversible, doesn’t alter corneal structure, and delivers excellent visual quality even at extreme prescriptions. For patients with powers between -9.0 and -18.0, ICL often produces sharper visual outcomes than would be achievable with corneal laser correction, because higher laser corrections can introduce subtle optical aberrations.
In some cases, a combination approach is used — for example, ICL to correct the bulk of the refractive error, followed by a light laser touch-up to fine-tune the result. This “bioptics” strategy is reserved for complex cases and requires careful planning. If you’ve been previously told your prescription is too high for LASIK, it’s worth getting a fresh assessment that includes all available procedure options, not just LASIK.
Other Factors That Affect Eligibility Beyond Power
Even if your eye power falls within the treatable range, other factors can affect whether you qualify. Your prescription must be stable for at least 12 months — a changing prescription means the correction may not hold long-term. You should be at least 18 years old, though most surgeons prefer 20 or older for optimal stability. Age considerations also apply at the upper end: patients over 40 need to account for presbyopia, which LASIK doesn’t address.
Corneal conditions like keratoconus, uncontrolled dry eye disease, autoimmune disorders, and certain medications can also disqualify candidates regardless of power. The comprehensive pre-operative evaluation at Visual Aids Centre screens for all of these factors to ensure your specific procedure is both safe and likely to deliver the visual outcome you expect.
How Visual Aids Centre Evaluates High-Power Patients
At Visual Aids Centre, every patient undergoes a detailed evaluation that goes well beyond checking their spectacle prescription. The process includes corneal pachymetry (thickness mapping at multiple points), anterior and posterior corneal topography, aberrometry to map optical irregularities, and a dilated retinal examination — particularly important in high myopes, who carry a higher risk of retinal tears and peripheral degeneration.
Based on these results, the team determines whether LASIK, SMILE Pro, ICL, TransPRK, or a combination approach offers the safest and most effective correction for your specific eyes. High-power patients are never shoehorned into a single procedure — the recommendation follows the data, not a one-size-fits-all protocol.
Conclusion
The maximum eye power for LASIK is approximately -8.0 D for myopia and +5.0 D for hyperopia — but that number is meaningful only in the context of your corneal thickness, astigmatism, prescription stability, and overall eye health. SMILE Pro extends the range to around -10.0 D, and ICL covers corrections up to -18.0 D or beyond. The right answer for your eyes depends on a thorough evaluation, not a generic limit. If you want to know exactly which options are available for your specific prescription, book a consultation and get a personalised assessment from our team.
Frequently Asked Questions (FAQs)
Can LASIK correct -10 eye power?
Standard LASIK typically cannot safely correct -10.0 D. SMILE Pro may be suitable up to -10.0 D depending on corneal thickness, or ICL can be used for powers this high.
What is the maximum cylindrical power LASIK can treat?
LASIK can generally correct up to 6.0 dioptres of astigmatism. Topography-guided platforms like Contoura Vision may offer better results for complex astigmatism patterns.
Is there a minimum eye power required for LASIK?
Most surgeons require at least -1.0 D of myopia (or equivalent refractive error) to justify the procedure. Very low powers may not produce enough benefit to warrant surgery.
Can someone with -9 power get LASIK?
Possibly, if their corneal thickness is sufficient. Many -9.0 patients are better served by SMILE Pro or ICL, which handle higher corrections more safely.
Why does corneal thickness matter more than eye power?
Each dioptre of correction requires removing corneal tissue. If your cornea is too thin, removing enough tissue would weaken it dangerously — regardless of how common your prescription is.
Is ICL better than LASIK for high power?
For powers above -8.0 D, ICL generally delivers better visual quality and is structurally safer because it doesn’t remove any corneal tissue. It’s also reversible if needed.
