Introduction
LASIK is not appropriate for every patient who wants it. The procedure permanently reshapes the cornea using laser energy, and that permanence means that selecting the right patients — and declining the wrong ones — is one of the most consequential decisions a refractive surgeon makes. A patient who is a poor LASIK candidate but who undergoes the procedure anyway faces a meaningfully elevated risk of complications that may be difficult or impossible to fully correct.
Understanding the candidacy criteria for LASIK serves two purposes. For patients who are good candidates, it provides confidence and sets appropriate expectations for what the procedure can achieve. For patients who are not good candidates — or who fall in a borderline zone — it provides a framework for understanding why their surgeon might recommend caution, alternative procedures, or additional evaluation.
The LASIK Surgery Awards program specifically evaluates practices on the rigor of their candidacy assessment, because a practice that screens patients appropriately is one that puts clinical judgment ahead of revenue. This page covers every major candidacy criterion in detail — what the criteria are, why they exist, and what options exist for patients who do not qualify.
Section 1: The Core Candidacy Criteria
What Surgeons Evaluate and Why Each Factor Matters
LASIK candidacy is not a binary pass/fail determination based on a single test. It is a multi-factor assessment that integrates anatomical measurements, prescription characteristics, systemic health status, and lifestyle considerations. Each factor addresses a specific risk category.
Age Requirements
LASIK is FDA-approved for patients 18 years of age and older. Most surgeons prefer to wait until patients are in their mid-20s to ensure full refractive stability — the prescription should not have changed by more than 0.50 diopters per year for at least two consecutive years before surgery is considered.
Operating before the prescription stabilizes produces a higher rate of regression, meaning that the cornea may continue to change shape in response to the patient’s ongoing refractive development, requiring glasses or contact lenses again after a period of good uncorrected vision. This does not harm the patient directly, but it does mean the procedure has not achieved a durable result.
On the other end of the age spectrum, there is no absolute upper age limit for LASIK — provided the patient meets all other candidacy criteria and has realistic expectations about presbyopia. Patients in their 40s and older will develop presbyopia (age-related near vision loss) regardless of LASIK, and while the procedure can achieve excellent distance vision, it does not prevent or reverse presbyopia.
Refractive Range
LASIK is FDA-approved to treat myopia (nearsightedness) up to approximately minus 12.00 diopters, hyperopia (farsightedness) up to approximately plus 6.00 diopters, and astigmatism up to approximately 6.00 diopters. However, FDA-approved ranges and practically safe treatment ranges are not identical.
Most surgeons are conservative at the higher end of the approved treatment range, because high-prescription treatments require greater ablation depth — meaning more corneal tissue is removed — which reduces the residual stromal bed thickness and increases biomechanical risk. Many surgeons apply more conservative upper limits in practice than the FDA-approved maximums, and this conservatism is an indicator of sound clinical judgment rather than limitation.
Patients with prescriptions at the high end of the treatable range should have a frank discussion with their surgeon about expected outcomes, the adequacy of their corneal thickness, and whether an alternative procedure such as an implantable collamer lens (ICL) might be more appropriate.
Corneal Thickness and Residual Stromal Bed
The cornea must be thick enough to safely accommodate the planned ablation depth (which correlates with the prescription being treated) plus the flap thickness. The residual stromal bed — the corneal tissue remaining after flap creation and laser ablation — must be at least 250 microns, and most safety-conscious surgeons prefer to maintain 300 microns or more.
Patients with corneas below approximately 480 microns central thickness (the exact threshold depends on their prescription and planned flap parameters) may not have sufficient tissue for safe LASIK. These patients should be considered for PRK (which avoids flap creation, preserving an additional 100 to 130 microns of tissue) or ICL (which adds a lens inside the eye without removing corneal tissue).
Corneal Topography and Regularity
The corneal surface must be regular and symmetric for LASIK to produce a high-quality optical outcome. Irregular corneas — particularly those showing patterns associated with keratoconus or pellucid marginal degeneration — are contraindications to LASIK.
Keratoconus is a condition in which the cornea progressively thins and steepens, often in an irregular, asymmetric pattern. LASIK performed on a keratoconic cornea can accelerate the thinning process and produce post-LASIK ectasia — a serious, sometimes vision-threatening complication. Even very mild or suspect keratoconus patterns (sometimes called forme fruste keratoconus) are a contraindication to LASIK in the view of most refractive surgery specialists.
Advanced topography and tomography imaging can detect keratoconus patterns before they are clinically apparent, which is precisely why this imaging is a required component of thorough candidacy screening.
Dry Eye Disease
Dry eye disease is a relative contraindication to LASIK. Moderate to severe dry eye at baseline is a disqualifying finding for most patients because LASIK temporarily reduces corneal sensation by severing corneal nerves during flap creation, which reduces reflex tear production and can significantly exacerbate pre-existing dry eye for a period of months to a year after surgery.
Patients with mild dry eye may proceed with LASIK after optimization of their tear film — typically a course of artificial tears, anti-inflammatory drops, and in some cases, punctal plug placement to conserve natural tears. Patients with more significant dry eye disease are better served by PRK (which preserves more corneal nerves relative to LASIK flap techniques) or by addressing their dry eye more fully before surgical candidacy is reassessed.
Section 2: Additional Factors That Affect Candidacy
Health Conditions, Lifestyle, and Individual Circumstances
Beyond the core anatomical criteria, a complete candidacy evaluation considers additional health and lifestyle factors that can influence surgical outcomes.
Systemic Health Conditions
Autoimmune conditions — including rheumatoid arthritis, lupus, Sjögren syndrome, and others — can impair wound healing and increase infection susceptibility. These conditions do not absolutely disqualify patients from LASIK in all cases, but they warrant careful discussion with the surgeon and often with the patient’s rheumatologist or internist before proceeding.
Diabetes, particularly uncontrolled diabetes with elevated glycated hemoglobin, is also associated with impaired wound healing and increased risk of post-operative complications. Well-controlled diabetes may not preclude LASIK candidacy, but it requires careful evaluation.
Patients taking immunosuppressive medications — including corticosteroids and biologic agents — present an elevated infection risk that must be evaluated on a case-by-case basis.
Pregnancy and Breastfeeding
Pregnancy causes significant hormonal changes that temporarily shift refractive error. Operating during pregnancy or breastfeeding risks producing a result that changes when hormonal levels normalize, potentially leaving the patient with a different prescription than intended. LASIK should be deferred until at least three months after breastfeeding has ended and the prescription has returned to a stable baseline.
Pupil Size and Occupation
Large scotopic pupils were historically considered a significant risk factor for post-LASIK halos and starbursts, particularly in night driving situations. Current-generation laser platforms with larger optical zones have reduced but not entirely eliminated this concern. Patients in professions that require excellent low-light vision — pilots, law enforcement, emergency responders — should discuss their occupational requirements explicitly with their surgeon. Aviation authorities in some countries have specific return-to-flight protocols after refractive surgery that should be investigated before proceeding.
Contact Sports and Physical Activity
Patients who participate in martial arts, boxing, or other contact sports where blows to the head are possible face an elevated risk of flap displacement after LASIK. The LASIK flap never fully re-adheres with the strength of intact corneal tissue, meaning that significant blunt trauma years after surgery can theoretically displace the flap. For these patients, PRK — which creates no flap — is generally the preferred alternative.
Section 3: Alternatives When LASIK Is Not Appropriate
Options for Patients Who Do Not Qualify
Patients who do not meet LASIK candidacy criteria are not without options. A range of alternative refractive procedures addresses different candidacy scenarios.
PRK (Photorefractive Keratectomy)
PRK uses the same excimer laser ablation as LASIK but without creating a flap. The surface epithelium is removed, the laser is applied directly to the corneal surface, and the epithelium regenerates over the following days. PRK avoids flap-related complications, is appropriate for patients with thinner corneas, and is preferred for patients in contact sports or certain military and aviation occupations. The trade-off is a longer, more uncomfortable recovery — visual clarity takes several days to a week to emerge, compared to within hours for LASIK, and the full healing process extends over several months.
LASEK and Epi-LASIK
LASEK and Epi-LASIK are variations of PRK that involve different handling of the surface epithelial layer. Their outcomes are broadly comparable to PRK, and they are occasionally preferred for specific anatomical or comfort reasons.
SMILE (Small Incision Lenticule Extraction)
SMILE is an increasingly available alternative that creates no flap, using a femtosecond laser to carve a lenticule within the corneal stroma and remove it through a small incision. It preserves more anterior corneal nerve density than LASIK and may be associated with lower rates of post-operative dry eye. SMILE is currently approved for myopia and myopic astigmatism correction in the United States.
Implantable Collamer Lens (ICL)
ICL is a phakic intraocular lens implanted inside the eye in front of the natural crystalline lens. It is appropriate for patients with high prescriptions outside the safe range for laser correction, or for patients with corneas too thin for safe ablation. ICL has the advantage of being theoretically reversible (though it is not intended as a temporary solution) and does not require corneal tissue removal. See LASIK Technology and Innovation in Top Practices for more on ICL as part of the full refractive surgery option set.
Award-winning practices recognized by the LASIK Surgery Awards program typically offer — or provide referral access to — the full range of refractive surgery alternatives, ensuring that patients who are not LASIK candidates can still receive appropriate vision correction care.
Section 4: What Patients Should Understand About Borderline Candidacy
When the Answer Is “Maybe” Rather Than “Yes” or “No”
Some patients fall into a genuinely borderline zone on one or more candidacy criteria — a prescription at the upper end of the treatable range, a cornea with mildly asymmetric topography that does not clearly indicate keratoconus, or a dry eye presentation that is mild but present. In these situations, the responsible approach from an award-worthy surgeon involves honest discussion of the specific concern, its implications for outcomes and risk, and the decision framework that weighs surgical benefit against additional risk.
Patients in borderline situations may benefit from a second opinion from another experienced refractive surgeon. This is entirely appropriate, and a surgeon who discourages a second opinion in a borderline case should prompt skepticism. Strong surgeons welcome second opinions because they are confident in the soundness of their assessment.
For guidance on evaluating the quality of the consultation in which candidacy is assessed, see LASIK Consultation: What to Expect and What to Ask. For a full discussion of LASIK risks relevant to borderline candidates, see LASIK Risks and Complications: An Honest Assessment.
Frequently Asked Questions
Q: Can I get LASIK if I have astigmatism? Yes. LASIK is approved and effective for correcting astigmatism up to approximately 6.00 diopters. Many patients have some degree of astigmatism combined with myopia or hyperopia, and modern laser platforms handle combined corrections effectively.
Q: I have been told my corneas are thin. Does that disqualify me from all laser eye surgery? Not necessarily. PRK may be appropriate if your residual stromal bed calculation after PRK (which does not require flap creation) meets safety thresholds. ICL is an option that avoids corneal tissue removal entirely. A thorough evaluation by an experienced refractive surgeon will determine which options are safe for your specific anatomy.
Q: How stable does my prescription need to be before I qualify? The standard recommendation is stability of within 0.50 diopters per year for at least two years. Some surgeons prefer three years of stability for younger patients or for higher prescriptions. Bring records of your prescription history to your consultation.
Q: Does having dry eyes automatically disqualify me? Not automatically. Mild dry eye can often be managed pre-operatively to the point where LASIK candidacy can be reconsidered. Moderate to severe dry eye is a more significant concern that typically directs patients toward PRK, SMILE, or ICL rather than LASIK.
Next Steps
Understanding the candidacy criteria gives you a meaningful framework for approaching your consultation. If you meet the criteria, you can proceed with confidence. If you have concerns about one or more factors, you have the vocabulary to discuss them specifically with your surgeon.
The LASIK Surgery Awards program recognizes practices known for rigorous candidacy assessment — practices that decline patients appropriately and offer honest guidance to those who are borderline. Visit the program directory to find evaluated providers in your area.
*Candidacy criteria described on this page reflect general clinical guidelines. Individual assessment by a qualified ophthalmologist is required for any specific candidacy determination.*