LASIK Surgery for High Prescriptions: What Are the Limits?
If you have a high prescription, you’ve probably wondered whether LASIK is still an option for you. Maybe your glasses feel heavy, you struggle with thick lenses, or your contacts feel uncomfortable after long days. Or perhaps you’ve heard people say that high prescriptions automatically rule out LASIK, leaving you unsure about what’s actually possible.
The good news is that LASIK technology has advanced dramatically in recent years. Today, many people with strong prescriptions are suitable candidates far more than you might expect. However, LASIK does have safe upper limits, and your suitability depends on your corneal thickness, shape, eye health and the technology your clinic uses. Even if LASIK isn’t ideal for you, there are powerful alternatives that may give you better results.
In this guide, I want to help you understand exactly what counts as a “high” prescription, how far LASIK can go, which technologies help treat stronger powers, and when alternatives like ICLs or lens-based procedures may be the safer or more accurate choice. By the end, you’ll have a clear idea of your options and the next steps in choosing the right vision correction for you.
What Counts as a High Prescription?
Every clinic defines “high prescription” slightly differently, but there are widely accepted ranges.
Short-sightedness (myopia):
- Low: 0 to –3.00
- Moderate: –3.00 to –6.00
- High: –6.00 and above
- Very high: –10.00 and above
Long-sightedness (hyperopia):
- Low: +0 to +2.00
- Moderate: +2.00 to +4.00
- High: +4.00 and above
Astigmatism:
- High astigmatism is considered around 3.00D or above
If you’re in these higher ranges, LASIK eligibility becomes more dependent on corneal thickness and overall eye structure.
Can LASIK Correct High Prescriptions?
Yes, up to a point. LASIK can correct a wide range of prescriptions, but the limits exist to keep your cornea safe.
Typical LASIK correction limits:
- Myopia: up to around –10.00 (sometimes –12.00 in carefully selected cases)
- Hyperopia: up to around +4.00
- Astigmatism: up to around 6.00D
These limits vary slightly depending on the laser system, your corneal thickness and the surgeon’s assessment.
But here’s the important part:
Just because the prescription is treatable doesn’t automatically mean LASIK is the ideal option. Safety and long-term stability matter more than simply hitting a prescription number.
Why LASIK Has Upper Limits
LASIK reshapes your cornea by removing small amounts of tissue. For higher prescriptions, more tissue must be removed.
To keep your eyes safe, your cornea must:
- Be thick enough
- Have the right curvature
- Be biomechanically stable
- Have no signs of disease such as keratoconus
If too much tissue must be removed, your cornea may become unstable, leading to complications like ectasia. That’s why safety limits are in place.
How Corneal Thickness Affects LASIK Eligibility
Corneal thickness is one of the biggest factors in determining whether LASIK is safe for high prescriptions.
Average corneal thickness:
530–560 microns
LASIK typically requires:
- Around 14–16 microns removed per dioptre of myopia
- A residual corneal thickness of at least 250–300 microns after surgery
Meaning:
Higher prescriptions + thinner corneas = LASIK may not be suitable. But you may still qualify for PRK or ICLs.
The Role of Modern Technology in Treating Higher Prescriptions
Today’s lasers can treat stronger prescriptions more accurately than older systems. Technology has expanded suitability for many people.
Wavefront-Guided LASIK
Creates personalised treatment based on your eye’s unique imperfections.
Benefits:
- Higher accuracy
- Sharper night vision
- Better long-term clarity
Great for high myopia with distortion.
Topography-Guided LASIK
Uses your corneal shape to optimise treatment.
Benefits:
- Ideal for irregular corneas
- Smooths the corneal surface
- Reduces visual aberrations
Femtosecond Laser LASIK
Uses a laser, not a blade, to make a more precise flap.
Benefits:
- Suitable for more corneal shapes
- Safer for higher prescriptions
- Greater stability
SMILE (Small Incision Lenticule Extraction)
A newer procedure that can treat high myopia with minimal dryness.
Limits:
- Up to around –10.00
- Can correct up to around 3.00D of astigmatism
Suitable for people with high myopia who may not be ideal LASIK candidates.
When LASIK Is Not the Best Option for High Prescriptions
If your prescription is above LASIK’s safe limits, or your cornea isn’t suitable, your surgeon may recommend alternatives.
You may not be ideal for LASIK if:
- Your corneas are thin
- You have high hyperopia
- You have high astigmatism
- You have very dry eyes
- You have early signs of keratoconus
- Your pupil size is extremely large
But this doesn’t mean you’re stuck with glasses you likely have other excellent options.
The Best Alternatives to LASIK for High Prescriptions
If LASIK isn’t suitable, these alternatives can often treat even stronger prescriptions safely and effectively.
ICL (Implantable Collamer Lens)
One of the most popular LASIK alternatives for high prescriptions. An ICL is a thin lens implanted inside your eye (like a permanent contact lens).
Benefits:
- Treats extremely high myopia (up to –20.00+)
- Treats high hyperopia
- Treats high astigmatism
- Doesn’t remove any corneal tissue
- Completely reversible
- Excellent quality of vision
- Great for dry-eye patients
Many people unsuitable for LASIK get fantastic results with ICLs.
PRK (Photo-Refractive Keratectomy)
A surface laser treatment that doesn’t require a corneal flap.
Benefits:
- Safer for thin corneas
- Good for moderate to high prescriptions
- Lower ectasia risk
- Long-term stability
Healing is slower than LASIK, but the results are equally strong.
SMILE
A flap-free laser treatment ideal for high myopia.
Benefits:
- Treats up to –10.00
- Minimises dry eye
- Quick recovery
- Strong biomechanical stability
SMILE is increasingly popular for high prescriptions.
RLE (Refractive Lens Exchange)
Often recommended for people over 45 with strong hyperopia or presbyopia. Your natural lens is replaced with a permanent artificial lens, similar to cataract surgery.
Benefits:
- Permanent correction
- Prevents cataracts
- Treats extremely high prescriptions
- Excellent for long-sighted patients
A good option if your lens is already ageing.
How Surgeons Decide Whether LASIK Is Safe for You
Your suitability depends on several measurements.
Your surgeon will assess:
- Prescription strength
- Corneal thickness
- Corneal shape
- Biomechanical stability
- Tear film quality
- Age
- Eye pressure
- Pupil size
High prescriptions require extremely detailed screening to keep your eyes safe long term.
Can LASIK Still Work If You Have High Myopia?
Yes, many people with high myopia are still excellent candidates.
LASIK may be suitable if:
- Your corneas are thick enough
- Your prescription is stable
- You have no signs of corneal weakness
- You pass topography assessments
Even if LASIK isn’t recommended, SMILE or ICLs often are.
Can LASIK Correct High Hyperopia?
LASIK can correct hyperopia up to around +4.00, sometimes slightly higher.
But hyperopic LASIK:
- Removes more tissue
- Is less stable at higher ranges
- May need more careful screening
For prescriptions above +4.00, RLE or ICL may be better.
How LASIK Handles High Astigmatism
LASIK can correct up to around 6.00D of astigmatism with modern lasers.
High astigmatism may need:
- Topography-guided treatment
- Wavefront optimisation
- Corneal mapping
- Careful accuracy checks
Even if your astigmatism is too high for LASIK, PRK or ICL may still treat it.
Does LASIK Last Long-Term for High Prescriptions?
Yes, if you’re an appropriate candidate.
For high prescriptions, long-term stability is good as long as:
- The cornea is thick enough
- The surgery is conservative
- The surgeon uses modern technology
Regression risk is higher with strong prescriptions, but still relatively low.
Potential Risks When Treating High Prescriptions with LASIK
High-prescription LASIK is very safe when done correctly, but potential risks include:
- Dryness
- Glare or halos
- Regression
- Thin residual cornea
- Ectasia (rare but serious)
- Reduced contrast sensitivity
These risks increase as prescription strength increases, which is why precise screening is essential.
Signs LASIK May Still Be an Option for You
You may still be suitable for LASIK if:
- Your corneas are thick
- Your prescription hasn’t changed for 12 months
- You have healthy tear film
- You have no irregularities on topography
- Your surgeon approves after detailed testing
The only way to know is through a full consultation.
Expected Results After LASIK with High Prescriptions
If you’re suitable, you can expect:
- Clearer day and night vision
- High accuracy
- Good long-term stability
- Sharp distance focus
- Comfortable visual performance
Your surgeon may recommend combining LASIK with enhancement techniques for optimal clarity.
FAQs:
- Can LASIK really correct very high prescriptions?
Yes, LASIK can correct high prescriptions, but only within safe limits that protect your cornea. If you’re severely short-sighted, you may still qualify as long as your cornea is thick enough and your eye structure is healthy. Modern laser systems have made it possible to treat much higher prescriptions than before, but surgeons will always prioritise safety over numbers. Even if you’re just above the typical LASIK limit, there’s still a chance another procedure like SMILE or ICLs may give you just as clear, if not better, long-term vision. - How do I know if my prescription is “too high” for LASIK?
Your prescription becomes “high” when the laser would need to remove more tissue than what’s considered biomechanically safe. This isn’t something you can judge from your glasses prescription alone. You need a full assessment that checks corneal thickness, curvature, eye pressure and topography. People with the same prescription can have totally different eye structures, which is why some individuals with strong powers are suitable while others aren’t. - Is LASIK safe if I have high myopia?
It can be, provided your cornea has enough thickness and stability. High myopia isn’t an automatic disqualifier anymore. Surgeons use corneal mapping and biomechanical tests to see how much tissue your eyes can safely tolerate. If everything looks healthy, LASIK may still offer excellent clarity. If not, an ICL or SMILE procedure may be safer while still giving you sharp distance vision. - What if my corneas are too thin for LASIK?
Thin corneas don’t necessarily end your hopes of ditching glasses. They simply mean LASIK may not be the safest approach. PRK and SMILE are both excellent alternatives because they either remove less tissue or avoid flap creation altogether. Many people with thin corneas still achieve the same visual results as LASIK candidates; they just take a different route to get there. - Can LASIK fix high hyperopia (long-sightedness)?
LASIK can treat hyperopia up to a certain level, usually around +4.00. The challenge with higher hyperopia is that it requires more tissue reshaping, which can be less stable in the long run. If you’re strongly long-sighted, lens-based treatments like RLE or ICLs often provide clearer, more predictable results. These options are especially helpful for people over 40 because they also address age-related changes in the natural lens. - How long do LASIK results last for strong prescriptions?
For most people, the results are very long-lasting as long as the cornea was suitable to begin with. If your prescription was very high, the risk of slight regression is a bit greater, but still relatively low when you’ve been properly screened. As long as your eyes were stable before surgery and the treatment was conservative, you can expect lasting clarity for many years. - What are the risks of treating a high prescription with LASIK?
The risks aren’t drastically different from standard LASIK, but they may be slightly more likely if your prescription is strong. You may experience dryness, glare or mild regression over time. In rare cases, over-treatment can weaken the cornea. That’s why surgeons take extra care when evaluating high prescriptions, often running additional scans to ensure your eyes can safely handle the reshaping. - Will LASIK affect cataract surgery in the future?
No, you can still have cataract surgery later in life, even if you’ve had LASIK. Your surgeon will simply need to use more advanced measurements to calculate your artificial lens accurately. People who’ve had LASIK routinely achieve excellent cataract-surgery outcomes, so it’s not something you need to worry about when deciding on laser eye treatment. - If LASIK isn’t suitable, what other options do I have?
You still have fantastic alternatives. SMILE is great for high myopia and causes less dryness, PRK works well for thin corneas, ICLs can treat extremely high prescriptions with high accuracy, and RLE is ideal for older patients with strong hyperopia or presbyopia. Many people unsuitable for LASIK actually get even sharper results from these alternatives. - How can I find out which procedure is genuinely best for me?
The only way to know for sure is to get a comprehensive eye assessment. Your surgeon will measure your corneal thickness, curvature, stability, tear film quality and overall eye health. These scans will show whether LASIK is safe, whether you’d benefit more from SMILE or ICLs, or whether a lens-based procedure makes more sense. Once you understand how your eyes behave, it becomes much easier to choose the treatment that will give you the clearest and safest long-term results.
Final Thoughts: Choosing the Safest Path When You Have a High Prescription
When you’re dealing with a strong prescription, it’s completely normal to wonder whether LASIK is still possible for you. The reality is that today’s technology has opened the door for many people who were previously told they weren’t suitable. But at the same time, the higher your prescription, the more important it becomes to make sure you’re choosing the right procedure for your eyes not just the one you’ve heard the most about.
Once you understand key factors like corneal thickness, topography, stability of your prescription and the limits of LASIK technology, it becomes much easier to see where you stand. You may discover that LASIK is safely within reach, or you might find that another treatment-like SMILE, PRK or ICLs offers better clarity and long-term stability. What matters most is choosing the option that protects your vision for life, rather than pushing your eyes beyond their safe limits.
A detailed assessment with an experienced surgeon will give you a clear picture of the best route forward. You’ll be able to understand exactly what’s possible with your eyes, what kind of results you can expect, and which treatment offers the safest and most accurate outcome based on your prescription. If you’re exploring whether Lasik surgery in London could benefit you, get in touch with us at Eye Clinic London to schedule your consultation.
References:
- Sandoval, H.P., Donnenfeld, E.D. & Solomon, K.D. (2016), LASIK for Myopia and Astigmatism: Safety, Efficacy, and Patient Satisfaction, Journal of Cataract & Refractive Surgery, 42(9), pp. 1224–1234. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5020014/
- Hjortdal, J., Ivarsen, A., Stjernegaard, A.H. & Grauslund, J. (2020), LASIK, SMILE, and PRK: Long-term Outcomes and Stability, Clinical Ophthalmology, 14, pp. 2283–2290.
Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7423788/ - Waring, G.O., Reinstein, D.Z. & Donnenfeld, E.D. (2018), Refractive Lens Exchange and High Refractive Errors, Journal of Refractive Surgery, 34(5), pp. 318–328.
Available at: https://pubmed.ncbi.nlm.nih.gov/29750755/ - Nancarrow, S.A. & Meades, S. (2020), Corneal Thickness and LASIK Eligibility: Biomechanical Considerations, Eye & Vision, 7(1), pp. 1–10. Available at: https://pubmed.ncbi.nlm.nih.gov/32527238/
- Siedlecki, J. & Kook, D. (2021), SMILE vs LASIK: Biomechanical Stability in High Myopia, Journal of Clinical Medicine, 10(12), 2554. Available at: https://www.mdpi.com/2077-0383/10/12/2554