LASIK Surgery for High Prescriptions: What Are the Limits?

If you have a high glasses prescription, you may be wondering whether LASIK can actually correct it and you’re not alone. Many people with strong myopia, hyperopia or significant astigmatism assume that their prescription is simply “too high” for laser eye surgery, often because they’ve heard outdated information or been told years ago that they weren’t suitable. But the landscape has changed dramatically. Thanks to advanced diagnostic tools, wavefront-guided treatments and faster, more precise laser platforms, many high-prescription patients who were once considered unsuitable can now safely achieve clearer, glasses-free vision with LASIK.

However, even with these improvements, there are still important limits to what LASIK can correct safely and predictably. The higher your prescription, the more corneal tissue needs to be reshaped and your corneal thickness ultimately determines how much can be removed without compromising long-term stability. This is why factors like corneal curvature, symmetry, biomechanical strength, and the overall health of your eye matter just as much as the prescription itself. In cases of very high myopia, extreme astigmatism, or thinner-than-average corneas, pushing LASIK beyond safe limits increases the risk of complications like ectasia. In such situations, alternative options like ICL surgery often offer sharper vision, greater precision for high prescriptions, and stronger long-term safety.

My goal in this article is to give you a clear, confident understanding of where these boundaries lie and how surgeons determine the safest option for you. By the end, you’ll know exactly how high your prescription can be for LASIK, which measurements matter during your assessment, and at what point another procedure may actually serve you better. With this knowledge, you’ll be empowered to make an informed decision about your vision correction journey one that balances clarity, safety and long-term eye health so you can move forward with confidence.

What Counts as a High Prescription?

When we talk about a “high prescription,” we’re generally referring to glasses or contact lens strengths that go beyond the mild or moderate range the point where your vision starts to rely heavily on corrective lenses for everyday tasks. For myopia, anything stronger than around –6.00 dioptres is often considered high, because the amount of laser correction needed increases the deeper your prescription goes. For hyperopia, the threshold is typically around +4.00 dioptres, since higher levels require more intense reshaping of the cornea. And for astigmatism, anything above 2.50–3.00 dioptres moves into the high category, as irregular curvature becomes more challenging to treat with the same precision and stability.

These thresholds matter because higher prescriptions require more tissue removal and more complex reshaping patterns to achieve crisp, stable vision. That’s why your surgeon will not only look at your prescription numbers, but also how your cornea is shaped, how thick it is, and whether it can safely withstand the amount of correction needed. Understanding where your prescription falls on this spectrum helps you better see why some people are excellent LASIK candidates while others may be guided toward safer alternatives like PRK or ICL not because their vision is “too bad,” but because long-term stability and eye health always come first.

High Myopia (Short-Sightedness): High myopia generally refers to prescriptions stronger than –6.00 dioptres, although some clinics classify –8.00 dioptres or higher as “very high myopia.” At this level, the eye is significantly longer than normal, causing light to focus in front of the retina. Higher levels of myopia increase the amount of corneal tissue that must be reshaped during laser surgery, which may limit eligibility for procedures like LASIK or LASEK. Patients with high myopia may be better suited for alternatives such as SMILE or implantable lenses (ICL), depending on corneal thickness and overall eye health.

High Hyperopia (Long-Sightedness): High hyperopia is typically defined as prescriptions above +4.00 dioptres. In these cases, the eye may be shorter than average or the cornea may not have enough focusing power, causing light to focus behind the retina. Hyperopic surgery requires the cornea to be steepened rather than flattened, which is biomechanically more demanding and sometimes less stable over time. Because more tissue must be reshaped to create a larger optical zone, high hyperopia can make LASEK or LASIK less predictable, and some patients may be advised to consider alternatives such as refractive lens exchange or ICL.

High Astigmatism: High astigmatism is usually defined as more than 3.00 dioptres. This occurs when the cornea has uneven curvature, causing light to scatter rather than focus cleanly. Correcting high astigmatism requires precise reshaping of the cornea and often demands larger or more customised laser patterns. If the astigmatism is irregular rather than regular, this may indicate corneal instability, making laser surgery unsuitable. Surgeons rely heavily on topography, tomography, and biomechanical testing to determine if laser correction is safe or whether alternatives such as PRK, SMILE, or ICL would offer better long-term stability.

If your prescription sits near or beyond these ranges, you’re generally considered a high-prescription patient, meaning your eyes require a stronger level of correction and your suitability for LASIK depends much more on factors like corneal thickness, curvature and overall eye health. This doesn’t automatically rule you out of laser surgery, but it does mean your assessment needs to be more detailed and your surgeon will look carefully at whether your corneas can safely handle the amount of reshaping required.

How LASIK Works (And Why There Are Limits)

LASIK works by reshaping the cornea the transparent front surface of your eye  so that light focuses correctly on the retina. To do this, your surgeon creates a thin corneal flap, lifts it, and then uses an excimer laser to precisely remove microscopic layers of tissue. The stronger your prescription, the more reshaping the laser must perform to bring your vision into focus. This is why high-prescription treatments naturally require more tissue removal: stronger myopia needs more flattening, stronger hyperopia needs more steepening, and significant astigmatism requires more complex sculpting patterns to regularise the corneal shape.

Because of this increased tissue removal, LASIK has very clear safety limits. Your surgeon must ensure that enough corneal thickness remains after the laser correction known as the residual stromal bed to keep your cornea strong, stable and healthy long-term. If too much tissue is removed, the cornea may weaken over time, increasing the risk of complications like ectasia. This is why high prescriptions demand more careful evaluation and why some patients are better suited to alternatives like PRK or ICL, which preserve more corneal strength. The key goal is always the same: achieving clear, stable vision without compromising the long-term health of your eyes.

LASIK Limits for Myopia, Hyperopia, and Astigmatism

Myopia (Short-Sightedness): Most clinics safely treat myopia in the range of –8.00D to –10.00D, but the final decision depends heavily on corneal thickness, corneal stability, and how much tissue needs to be removed. Higher levels of myopia require deeper ablation, which can thin the cornea more than is safe for long-term stability. In rare cases, patients with exceptionally thick and biomechanically strong corneas may be treated beyond –10.00D, but this is uncommon and only done using very conservative ablation patterns to protect structural integrity. Patients with extreme myopia often achieve more predictable results with SMILE or implantable lenses (ICL), which do not weaken the cornea.

Hyperopia (Long-Sightedness): Hyperopic laser correction has stricter limits than myopia because the cornea must be steepened rather than flattened, which is harder to stabilise over time. The widely accepted safe upper limit is around +4.00D, although some carefully selected patients may be treated up to +5.00D if their corneas are ideal in shape and strength. Beyond these levels, the risk of regression, fluctuating vision, and long-term instability increases significantly. Many patients with higher hyperopia are better suited for lens-based procedures such as refractive lens exchange (RLE) or ICLs.

Astigmatism: Most modern LASIK platforms can reliably treat astigmatism between 3.00D and 4.00D. When the astigmatism is higher, the cornea requires more complex reshaping, and the laser treatment becomes more sensitive to corneal stability and healing patterns. For safe correction, the corneal shape must be extremely regular and symmetrical. If the astigmatism is irregular or if tomography suggests early instability laser surgery may not be recommended. In such cases, alternatives like PRK, SMILE, or ICLs may provide a better combination of safety and visual quality.

Why LASIK Has These Limits

LASIK works by removing precise amounts of corneal tissue to reshape the eye and correct refractive errors. While the procedure is highly effective, there are natural limits to how much tissue can safely be removed. The main concern is maintaining the structural integrity of the cornea. If too much tissue is removed, the cornea can become weakened, which may lead to long-term complications such as corneal ectasia, irregular astigmatism, or reduced visual stability.

Two key measurements play a crucial role in determining whether a patient is a suitable candidate for LASIK:

Corneal Thickness (Pachymetry): This measurement indicates how thick your cornea is. Thicker corneas can tolerate more tissue removal, which allows surgeons to correct higher prescriptions safely. Conversely, thinner corneas limit the amount of laser correction possible because there is less tissue to work with, increasing the risk of weakening the eye. Pachymetry is usually measured in microns, and precise mapping of the cornea ensures that the laser removes only the necessary tissue while leaving enough behind for a strong and stable structure.

Residual Stromal Bed (RSB): The residual stromal bed is the layer of corneal tissue that remains after the laser reshaping is complete. Maintaining a safe RSB is essential to prevent corneal instability. Most surgeons consider a minimum RSB of 250–300 microns to be safe, although this can vary depending on individual corneal characteristics. If the RSB is too thin, the cornea may bulge or weaken over time, potentially causing visual problems or complications that may require further intervention.

By carefully evaluating these two factors the amount of tissue that needs to be removed and how much healthy cornea will remain afterwards along with your overall eye health and prescription strength, surgeons can determine whether LASIK is the safest choice for you. This thorough assessment helps ensure that the procedure not only improves your vision in the short term but also maintains long-term corneal stability, reducing the risk of complications and supporting clear, reliable vision for years to come.

Factors That Determine Whether You Qualify for LASIK

Even if your prescription is on the higher side, you may still qualify for LASIK depending on several key factors that influence both safety and long-term stability. Surgeons never look at prescription strength in isolation because it only tells part of the story. Instead, they assess the overall health, thickness and structure of your corneas, how stable your vision has been over the past few years, and whether your eyes show any signs of weakness or irregularity that could affect the outcome. This more holistic evaluation helps determine whether LASIK can reshape your cornea safely without compromising its strength.

They also consider your lifestyle, age, tear film quality and expectations, all of which play a crucial role in choosing the right procedure. For example, someone with a high prescription and strong, thick corneas may be an excellent LASIK candidate, while another person with a mild prescription but thin or irregular corneas may be better suited to LASEK, PRK or ICL surgery. By reviewing all these elements together, surgeons can recommend the safest and most effective approach for your eyes, ensuring not just clearer vision but also long-term stability and confidence in your results.

Corneal Thickness: You need a sufficiently thick cornea to safely remove the amount of tissue required for laser correction. Higher prescriptions demand deeper ablation, and if the cornea is too thin, removing that much tissue could compromise its strength. A thicker cornea provides a larger safety margin, allowing surgeons to correct stronger prescriptions while still leaving enough untouched tissue to maintain long-term stability. If the cornea is borderline thin, alternatives like PRK, SMILE (for myopia), or implantable lenses may be safer.

Corneal Shape: Corneal shape plays a major role in determining whether high-prescription LASIK is safe. During your assessment, your surgeon will use advanced corneal topography and tomography scans to analyse the surface and deeper layers of your cornea. These tests reveal any irregularities, early keratoconus, subtle signs of ectasia or even temporary distortions caused by long-term contact lens wear. If your cornea shows unusual patterns, weak spots or asymmetry, LASIK becomes unsafe because the reshaping needed for a high prescription could further destabilise the cornea. For this reason, irregular or suspicious corneas are generally not suitable for high-prescription LASIK, and alternative procedures may be recommended instead.

Prescription Stability: Your prescription must be stable for at least one year before undergoing LASIK, especially for higher prescriptions. High levels of myopia, hyperopia, or astigmatism have a greater likelihood of changing over time. Treating an unstable prescription increases the risk of regression, meaning your vision may drift back toward your old prescription after surgery. Stability ensures that your results are long-lasting and predictable.

Pupil Size: Large pupils can increase the likelihood of visual side effects, such as halos, glare, and starbursts especially at night. This is important for high-prescription LASIK patients because stronger corrections require larger optical zones. If the optical zone is smaller than your pupil size in the dark, peripheral light may enter untreated corneal areas, creating night-vision issues. Surgeons measure pupil size to determine whether LASIK is the best option or if another procedure would reduce nighttime symptoms.

Tear Film Health: Dry eye symptoms often increase temporarily after LASIK, and this effect can be more noticeable when treating higher prescriptions. A healthy tear film is essential for smooth healing and clear vision. If you already have dryness, your surgeon may recommend treatments beforehand such as lubricating drops, omega-3 supplements, or punctal plugs to improve your tear stability. In some cases, LASEK or SMILE may be preferred because they may worsen dry eye less than traditional LASIK.

Age: Age is another important factor when considering LASIK for high prescriptions, because your vision needs to be stable before any permanent reshaping of the cornea is done. Most surgeons prefer treating patients who are over 21, primarily because prescriptions tend to fluctuate during the late teenage years and early twenties. They also look for stability ideally no significant change in your glasses or contact lens numbers for at least one to two years to ensure the results remain accurate and long-lasting. If your vision is still changing quickly, especially with a high prescription, surgeons will usually recommend waiting until it stabilises to avoid the risk of undercorrection, regression or future enhancements.

What Happens If Your Prescription Is Too High for LASIK?

If your prescription is too high for LASIK, it doesn’t mean you’re out of luck when it comes to vision correction. High prescriptions require more corneal tissue to be removed for reshaping, and if your corneas aren’t thick or strong enough, LASIK could compromise long-term eye health. Thankfully, there are alternative procedures that are better suited to these situations. These options are designed to provide safe, effective correction even for very strong myopia, hyperopia, or astigmatism, often delivering sharper and more predictable results than LASIK could in the same circumstances.

Some of the most common alternatives include surface-based laser procedures like PRK or LASEK, which avoid creating a corneal flap and preserve more tissue, as well as implantable lenses such as ICL (Implantable Collamer Lens), which sit inside the eye and can correct very high prescriptions without removing corneal tissue at all. Each option has its own advantages depending on your corneal thickness, eye shape, prescription strength, and lifestyle needs. By understanding these alternatives, you can make an informed decision about which procedure offers the safest and most effective path to clear, stable vision.

Alternative Options for High Prescriptions: 

ICL Surgery (Implantable Contact Lens): For patients with very high prescriptions who aren’t suitable for LASIK, ICL surgery (Implantable Contact Lens) is often the ideal alternative. Instead of reshaping the cornea, a thin, flexible lens is placed inside the eye, between the natural lens and the iris, allowing correction of extremely high myopia sometimes up to –20.00D or more as well as high astigmatism, all without removing any corneal tissue. This preserves corneal thickness and structural integrity, making ICL especially safe for patients with thinner or flatter corneas. Another key advantage is that the procedure is reversible: the lens can be removed or replaced if your prescription changes, offering a flexible, long-term solution that provides sharp, stable vision while maintaining eye health.

SMILE Surgery: SMILE is another excellent option for patients with strong myopia who may not qualify for LASIK. Unlike LASIK, SMILE doesn’t require creating a corneal flap, which helps preserve corneal strength and reduces the risk of long-term complications. It also tends to cause less dry eye because fewer corneal nerves are disrupted during the procedure. Depending on the laser platform and your individual eye characteristics, SMILE can safely treat prescriptions up to around –10.00D, making it a strong alternative for patients with higher myopia who want a flap-free, minimally invasive solution.

PRK (Photo-Refractive Keratectomy): PRK is a surface-based laser procedure that doesn’t involve creating a corneal flap, which helps preserve more corneal thickness and strength. It’s particularly well-suited for patients with slightly higher prescriptions or thinner corneas, as it allows safe reshaping without compromising structural integrity. PRK is also an excellent choice for people with active lifestyles or those involved in contact sports, since there’s no flap to dislodge or injure. While the initial healing period is longer and recovery can be more uncomfortable compared to LASIK, the long-term visual results are excellent, providing stable, clear vision for years.

Can LASIK Make High Prescriptions Worse?

LASIK itself does not make your prescription worse, but treating high prescriptions requires extra caution. Strong myopia or astigmatism demands more corneal reshaping, which can lead to side effects such as increased dryness, night-time halos or glare, and a slightly higher chance of vision regression over time. In addition, removing more tissue for higher prescriptions results in a thinner residual cornea, which is why surgeons must carefully assess whether your eyes can safely handle the procedure.

The good news is that with proper evaluation and planning, these risks can be minimised dramatically. By measuring corneal thickness, mapping the cornea’s shape, checking prescription stability, and reviewing overall eye health, surgeons can determine the safest approach and customise the treatment for your eyes. This careful, personalised planning ensures that even patients with high prescriptions can achieve excellent, stable vision while maintaining long-term eye health.

Benefits of LASIK for High Prescriptions

If you qualify for LASIK with a high prescription, the benefits can be life-changing, sometimes even more so than for patients with lower prescriptions. Many people experience complete freedom from glasses or contact lenses, which can be especially meaningful if they’ve relied on strong lenses for years. Peripheral vision often improves, making everyday activities and sports safer and more enjoyable, while the convenience of clear vision from morning until night adds a new level of comfort and confidence to daily life.

High-prescription patients often report the greatest emotional impact from their results. Being able to wake up and see clearly without struggling with thick lenses, heavy glasses, or contact lenses that irritate the eyes can feel almost like a transformation. The combination of improved vision, enhanced safety for active lifestyles, and reduced dependence on corrective eyewear often leads to a lighter, more comfortable lifestyle making the benefits of LASIK not just practical, but deeply rewarding.

Risks to Consider Before LASIK for High Prescriptions

Before undergoing LASIK for a high prescription, it’s important to understand the potential risks, which tend to increase slightly as the level of correction rises. Common issues include night-time glare or halos, temporary or prolonged dryness, and a small chance of regression, where some of your original prescription gradually returns. Because higher prescriptions require more corneal reshaping, the residual cornea may be thinner, which makes careful preoperative assessment essential. In rare cases, excessive tissue removal can lead to ectasia, a condition where the cornea weakens and bulges over time.

The good news is that modern LASIK technology, combined with advanced screening and conservative treatment planning, dramatically reduces these risks. Surgeons can evaluate corneal thickness, shape, and biomechanical strength to ensure only safe amounts of tissue are removed. By tailoring the procedure to your individual eyes and prescription, LASIK can provide excellent visual outcomes while maintaining long-term corneal stability and minimizing complications, even for patients with high prescriptions.

How Surgeons Decide the Best Option for You

When deciding the best vision correction option for you, surgeons rely on a comprehensive series of scans and assessments. Corneal tomography and pachymetry measure the shape, thickness, and structural integrity of your cornea, while wavefront analysis maps how light travels through your eye to identify higher-order aberrations that could affect visual quality. Pupil size is measured to predict night-vision effects, and tear film evaluation assesses the risk of post-surgery dryness. Surgeons also check that your prescription has been stable over time, as fluctuating vision can affect the long-term success of any procedure.

All of these tests work together to create a detailed map of your eyes, allowing surgeons to determine whether LASIK is safe or whether another procedure, such as PRK, LASEK, SMILE, or ICL, would be a better fit. By evaluating every aspect of your corneal health, prescription strength, and visual needs, your surgeon can recommend the option that maximizes both safety and visual outcome, ensuring that you achieve clear, stable vision while minimizing risks.

What to Expect If You Have High-Prescription LASIK

During the procedure: During the LASIK procedure, numbing drops are applied to ensure the entire process is painless, so you won’t feel any sharp sensations. Once the corneal flap is created, the excimer laser reshapes the cornea within seconds, precisely correcting your prescription. Most patients only notice a mild pressure or pushing sensation on the eye during this time, but no actual pain is experienced. The combination of quick laser application and effective numbing makes the procedure surprisingly comfortable, even for those undergoing high-prescription corrections.

After the procedure: After LASIK, it’s normal to experience blurry or hazy vision for a few hours while your eyes adjust. For most patients, vision becomes noticeably clearer by the next morning, allowing you to resume many daily activities quickly. Light sensitivity is common initially, especially in bright environments, and mild dryness may persist, gradually improving over several weeks to months as your eyes fully heal. These temporary side effects are part of the normal recovery process and generally resolve without long-term issues, making the overall healing period relatively short and manageable even for high-prescription patients.

Most patients achieve excellent clarity very quickly after LASIK, often noticing a dramatic improvement within hours of the procedure. By the next day, many can see clearly enough to carry out daily activities without glasses or contact lenses, which can feel almost life-changing for those who have relied on strong prescriptions for years. While some minor blurriness, light sensitivity, or dryness may linger temporarily, the overall improvement in vision is immediate and striking. This rapid and noticeable enhancement in visual clarity is one of the biggest advantages of LASIK, making it especially appealing for high-prescription patients eager to regain independence from corrective lenses.

Night Vision and High Prescriptions

Night vision issues, such as glare, halos, or starbursts, are more common in patients with high prescriptions because the laser must remove more corneal tissue to achieve the desired correction. These effects are particularly noticeable if your pupils are large, if the treatment zone created by the laser is relatively small, or if the cornea heals unevenly after surgery. High-prescription eyes are more sensitive to these factors, which is why careful planning and customised treatment parameters are essential to minimise night-vision disturbances.

Modern blade-free LASIK techniques, often called “all-laser” LASIK, use larger optical zones that better match the size of your pupils under low-light conditions. By creating a more uniform treatment area and precisely controlling the amount of tissue removed, these advanced procedures significantly reduce night glare and halos. As a result, even patients with high prescriptions can enjoy clearer vision at night with minimal visual disturbances, making LASIK both effective and safe for their lifestyle needs.

LASIK vs ICL for High Prescriptions: Which Is Better?

When it comes to correcting high prescriptions, both LASIK and ICL (Implantable Collamer Lens) surgery are effective options, but they work in very different ways. LASIK reshapes the cornea to focus light correctly, offering rapid recovery, minimal invasiveness, and long-term stability for many patients. However, for very high prescriptions or thinner corneas, LASIK may be limited by the amount of tissue that can safely be removed, and patients may experience slightly higher risks of dryness, night glare, or regression.

ICL, on the other hand, involves implanting a thin lens inside the eye without altering the cornea. This makes it ideal for extremely high myopia, significant astigmatism, or patients with thinner corneas who aren’t ideal LASIK candidates. Recovery is quick, results are highly predictable, and the procedure is reversible if needed. Choosing between LASIK and ICL depends on factors like prescription strength, corneal thickness, lifestyle, and personal preference, with your surgeon guiding you to the option that maximises both safety and visual outcome.

LASIK is better if: LASIK is generally the better choice if your corneas are sufficiently thick and your prescription falls within a safe range for corneal reshaping. It’s ideal for patients who are comfortable with a flap-based procedure and want the convenience of a rapid recovery, often achieving clear vision within hours to a day. Because LASIK is minimally invasive and precise, it offers excellent results for patients whose eyes meet these criteria, allowing them to return to daily activities quickly while enjoying long-term visual clarity.

ICL is better if: ICL is often the better option if you have a very high prescription or thinner corneas that make LASIK unsafe. It’s particularly suitable for patients who want a reversible procedure, those with dry eyes that could worsen with corneal surgery, or anyone who isn’t a good candidate for LASIK due to corneal limitations or other eye conditions. By placing a lens inside the eye rather than reshaping the cornea, ICL provides sharp, stable vision while preserving corneal integrity, making it an excellent choice for high-prescription patients seeking both safety and long-term flexibility.

Many surgeons consider ICL the premium solution for very high prescriptions because it safely corrects vision without removing any corneal tissue. Its ability to treat extreme myopia or high astigmatism, combined with a reversible and highly predictable outcome, makes it the preferred choice when LASIK or other laser procedures are not suitable.

FAQs:

1. Can LASIK correct very high prescriptions?
   LASIK can correct a wide range of prescriptions, but there is a point at which the surgery becomes unsafe because too much corneal tissue would need to be removed. Most clinics safely treat myopia up to around -8.00D to -10.00D, hyperopia up to +4.00D and astigmatism up to about 4.00D. If your prescription goes beyond these limits, it doesn’t mean you cannot achieve clear, glasses-free vision it simply means another procedure such as ICL surgery or SMILE may be a better match for your eyes.
2. Why can’t LASIK treat extremely high myopia?
   Extremely high myopia requires a large amount of corneal reshaping, and this can thin the cornea more than is safe. Your surgeon must always leave a strong layer of tissue behind to maintain the long-term health and stability of your eye. If your prescription would require removing too much tissue, then LASIK becomes unsuitable not because the treatment can’t correct the power, but because it could compromise the strength of your cornea in the future.
3. Is LASIK safe if I have thin corneas?
   Thin corneas are one of the main reasons someone may not qualify for LASIK. The procedure requires removing a precise layer of tissue, and if the cornea starts out thin, the remaining tissue may not be enough to keep the eye structurally stable. In these cases, surgeons often recommend SMILE, PRK or ICL surgery because these options preserve more corneal tissue and are considered safer for long-term visual results.
4. Can LASIK cause regression for high prescriptions?
   Regression is more likely when treating higher prescriptions simply because the cornea has to undergo more reshaping. Although most patients maintain excellent long-term vision, a small percentage may notice a slight shift back toward their original prescription months or years later. This doesn’t mean the procedure failed; rather, it reflects how the eye heals and adapts. Enhancements are possible in many cases, and alternatives like ICL surgery have an even lower risk of regression for very high powers.
5. Is LASIK suitable for high astigmatism?
   LASIK can correct astigmatism very effectively, but only up to a certain level. Most modern laser systems treat up to around 3.00D to 4.00D, although the exact limit depends on corneal shape and stability. The procedure works by reshaping the cornea in a way that evens out the irregular curvature. If your astigmatism is higher than the treatable range, surgeons often prefer ICLs or a combined approach because these methods deliver more predictable results.
6. Does LASIK recovery take longer for high prescriptions?
   Recovery after LASIK is generally quick, but high-prescription patients may notice slightly more dryness, fluctuating vision or night halos during the first few weeks. This is because the cornea undergoes more reshaping to achieve the desired correction. Even so, most people still see very clearly within 24 hours. The overall healing timeline remains similar, but full visual stability may take a bit longer compared to someone with a mild prescription.
7. Is ICL surgery better than LASIK for very high prescriptions?
   ICL surgery is often the preferred option for high prescriptions because it doesn’t remove any corneal tissue. Instead, a thin lens is placed inside the eye to correct the refractive error. This makes it ideal for people with thin corneas, dry eyes or extreme myopia, even up to -20.00D or more. Many surgeons consider ICL surgery the safest and most accurate choice for strong prescriptions because the results are stable, high-definition and reversible.
8. Can high-prescription patients still develop night glare after LASIK?
   Night glare can occur in any LASIK patient, but it is more noticeable when treating stronger prescriptions. This is because the ablation zone needs to be larger, and the cornea may take longer to settle. Modern wavefront and topography-guided technologies reduce the likelihood of night glare significantly by smoothing out subtle irregularities in the corneal surface. In most cases, any visual halos that appear early on continue to improve as the eye heals.
9. Will LASIK make my corneas too thin?
   LASIK only becomes risky when the surgery would leave the cornea thinner than the recommended safety threshold. This is why your surgeon performs corneal mapping and thickness measurements before determining whether LASIK is appropriate for you. If the calculations show that the procedure would leave insufficient tissue, LASIK is simply avoided, and you are guided toward a safer alternative rather than proceeding with a risky approach.
10. What is the best option if I’m not suitable for LASIK due to a high prescription?
    If LASIK isn’t suitable for your eyes, there are still excellent options available. ICL surgery is often the top choice for very high prescriptions because it provides strong, stable correction without affecting corneal thickness. PRK is a good alternative for moderately high prescriptions or thin corneas, while SMILE is ideal for certain ranges of myopia with less impact on corneal nerves. The right choice depends entirely on your eye structure, prescription levels and long-term visual goals.

Final Thought: Choosing the Best Vision Correction for High Prescriptions

High-prescription patients no longer have to assume that glasses or contact lenses are their only option. While LASIK has clear limits based on corneal thickness, prescription strength, and overall eye health, modern laser technology has expanded the number of people who can safely benefit from this procedure. For prescriptions beyond LASIK’s safe range, alternatives such as ICL surgery, SMILE, or PRK offer effective and predictable vision correction while preserving corneal integrity.

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. A detailed assessment will help you understand which treatment is safest and most effective for your long-term visual goals. With the right approach, achieving clearer, glasses-free vision is well within reach.

References:

1. Kanclerz, P. & Khoramnia, R. (2021) ‘Flap Thickness and the Risk of Complications in Mechanical Microkeratome and Femtosecond Laser In Situ Keratomileusis: A Literature Review and Statistical Analysis’, Diagnostics, 11(9), 1588. Available at: https://www.mdpi.com/2075-4418/11/9/1588
2. Juda, M. et al. (2024) ‘Clinical Evaluation of Corneal Endothelial Parameters Following Laser Refractive Surgery in Myopic Patients: A Review’, Journal of Clinical Medicine, 13(6), 1665. Available at: https://www.mdpi.com/2077-0383/13/6/1665
3. Santhiago, M. R. et al. (2015) ‘Role of Percent Tissue Altered on Ectasia After LASIK in Eyes With Suspicious Preoperative Corneal Topography’, Clinical Ophthalmology, 9, pp. 1695–1701. PubMed [no DOI]. Available at: https://pubmed.ncbi.nlm.nih.gov/25884581/
4. Twelve-year follow-up of laser in situ keratomileusis for moderate to high myopia study group (2017) ‘Twelve‑Year Follow‑Up of Laser In Situ Keratomileusis for Moderate to High Myopia’, Journal of Refractive Surgery, 33(5), pp. 330–334. PubMed. Available at: https://pubmed.ncbi.nlm.nih.gov/28596969/
5. Harissi‑Dagher, M., Frimmel, S. A. F. & Melki, S. (2009) ‘High myopia as a risk factor for post‑LASIK ectasia: a case report’, Digital Journal of Ophthalmology, 15(1), pp. 9–13. PMC article. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC5735597/