Source-backed guidance on SMILE eye surgery eligibility, including age requirements, prescription parameters, corneal criteria, and factors that may affect candidacy.
Last reviewed: 2026-05-06
9 min read
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Content is educational and planning-oriented. It does not replace diagnosis, treatment, or personalized medical advice from a licensed healthcare professional. Outcomes vary by individual case.
SMILE requires candidates to be at least 22 years old with a stable prescription for at least one year.
Approved refractive ranges include myopia from -1.00 to -10.00 diopters and myopic astigmatism up to -3.00 diopters.
Central corneal thickness typically needs to exceed 475 μm with healthy topography.
Certain conditions such as pregnancy, uncontrolled diabetes, and active eye infections may temporarily or permanently disqualify candidates.
Educational information only
This content is general education and does not replace evaluation by a licensed clinician. If you have symptoms, complications, or urgent concerns, seek in-person medical care.
Core Context
SMILE (Small Incision Lenticule Extraction) is a laser refractive surgery that reshapes the cornea by creating and removing a small lens-shaped piece of tissue called a lenticule through a small incision. This differs from LASIK, which creates a corneal flap, and PRK, which removes the outer corneal layer entirely [S1].
Understanding candidacy requirements before scheduling a consultation can help you have more productive conversations with eye care providers and set realistic expectations about what the procedure may achieve for your vision. This resource outlines the general eligibility criteria that eye care professionals use when evaluating patients for SMILE surgery [S2].
If SMILE is not suitable for your eyes, other options such as LASIK, PRK, or implantable collamer lenses (ICL) may be appropriate. The right procedure depends on your individual eye anatomy, prescription, and lifestyle needs. A comprehensive evaluation by a qualified refractive surgeon can determine which approach, if any, may be suitable for your situation [S1].
For additional information about eye care procedures and options, explore our Eye Care Resources hub.
This resource provides general educational information about SMILE candidacy criteria. Only a qualified ophthalmologist can determine whether SMILE or any other procedure is appropriate for your specific eyes.
Decision Criteria
Age and Prescription Stability
The FDA has approved SMILE for patients who are at least 22 years of age [S1]. This minimum age requirement exists because younger patients may still experience natural vision changes as their eyes continue to develop. Beyond the age threshold, your prescription must have remained stable for at least one year before surgery [S1].
Prescription stability indicates that your eyes have reached a consistent refractive state. Even if you fall within the approved prescription range, ongoing changes in your vision could compromise surgical outcomes. If your prescription has shifted significantly within the past year, your surgeon may recommend waiting until stability is demonstrated before proceeding [S1].
Refractive Error Parameters
SMILE is approved for correcting myopia (nearsightedness) and myopic astigmatism. The FDA-approved refractive range for myopia extends from -1.00 to -10.00 diopters [S2]. For patients with myopic astigmatism, SMILE can correct up to -3.00 diopters of cylinder (astigmatic component), a range that was expanded through FDA approval in 2018 [S2].
These parameters represent the range in which SMILE has been studied and approved. Surgeons may consider patients outside these ranges on a case-by-case basis, but FDA-approved indications provide the clinical evidence base for predictable outcomes [S2].
Corneal Requirements
The cornea must meet specific structural criteria for SMILE to be performed safely. Central corneal thickness typically needs to exceed 475 μm to allow adequate tissue removal while maintaining sufficient residual stromal strength [S2]. This measurement is obtained during the pre-operative evaluation using specialized imaging equipment.
Healthy corneal topography is essential. The corneal surface must be regular without irregularities or signs of thinning disorders such as keratoconus [S1]. Surgeons evaluate the corneal map for symmetry, curvature patterns, and any localized thinning that might indicate elevated risk for complications [S2].
During the procedure, a specific amount of corneal tissue is removed to create the lenticule. An adequate residual stromal bed must remain after this removal to preserve corneal structural integrity [S2]. Patients with thinner corneas or higher prescriptions may have less margin for tissue removal, which can affect candidacy [S2].
Ocular Health Conditions
Active eye infections or inflammation must be resolved before SMILE can be considered [S1]. These conditions affect the corneal surface and increase the risk of complications during and after surgery. Your surgeon will examine for any active conjunctivitis, keratitis, or other ocular inflammation.
Keratoconus and other corneal thinning disorders typically disqualify patients from SMILE [S2]. These conditions involve progressive weakening of the corneal structure, and refractive surgery may accelerate progression or lead to irregular healing. forme fruste keratoconus (subclinical keratoconus) is also a contraindication [S2].
Significant dry eye disease requires evaluation and often treatment before surgery can proceed [S1]. Refractive surgery can temporarily worsen dry eye symptoms, so surgeons typically want dry eye conditions to be well-managed before proceeding [S1].
Systemic Health Factors
Pregnancy and breastfeeding create temporary contraindications due to hormonal changes that affect refraction [S3]. Fluid retention during pregnancy can alter corneal thickness and shape, leading to unstable vision measurements. Surgeons generally recommend waiting until after pregnancy and breastfeeding have ended, and vision has stabilized, before proceeding.
Uncontrolled diabetes mellitus is a contraindication because blood sugar fluctuations affect refraction and can impair corneal healing [S3]. Patients with well-controlled diabetes may still be candidates after careful evaluation, but those with unstable blood sugar are typically advised to defer surgery.
Certain medications can affect candidacy. Isotretinoin (Accutane) and amiodarone have been associated with impaired corneal healing and may affect surgical outcomes [S3]. Autoimmune conditions such as rheumatoid arthritis and Sjogren's syndrome may increase the risk of dry eye complications and delayed healing [S3].
Important Considerations
Even if you have one or more relative contraindications, a thorough evaluation by an experienced refractive surgeon may identify management strategies or alternative procedures that could be appropriate. Not all disqualifying factors are permanent.
Source-Backed Facts
FDA Approval and Clinical Evidence
SMILE received initial FDA approval for myopia correction and later expanded to include myopic astigmatism in 2018 [S2]. The approval process included clinical trials demonstrating safety and efficacy within the approved parameters. This regulatory history establishes the clinical evidence base for predictable outcomes within the approved ranges.
The procedure has been performed internationally since approximately 2011 and in the United States since FDA approval, accumulating substantial real-world clinical experience alongside trial data [S2].
Candidacy Variation
Clinical data indicate that candidacy rates vary based on the specific population being evaluated. Not all patients who present for consultation meet the necessary criteria. Studies have shown that comprehensive pre-operative screening identifies a significant percentage of patients who require alternative approaches or deferred treatment [S2].
Candidacy determination requires in-person examination with advanced diagnostic equipment. Online eligibility checklists and self-assessment tools can provide general guidance but cannot replace the detailed measurements and clinical examination performed by a qualified surgeon [S1].
Risk Controls
Why Comprehensive Screening Matters
SMILE is an elective procedure that should only proceed when pre-operative evaluation confirms acceptable risk-benefit balance for the individual patient. Comprehensive screening serves multiple purposes: identifying contraindications, establishing baseline measurements for comparison, and ensuring the patient's expectations align with realistic outcomes [S1].
The screening appointment typically includes corneal topography, pachymetry (thickness measurement), wavefront analysis, pupil assessment, tear film evaluation, and general ocular health examination. These tests take approximately two to three hours and provide the data needed to determine candidacy and surgical planning [S1].
When visiting our partner facilities for evaluation, expect a thorough assessment using modern diagnostic technology. Qualified surgeons specializing in refractive procedures will review your results and discuss whether SMILE or an alternative approach may be suitable for your eyes.
Managing Identified Concerns
When initial screening identifies concerns, several pathways may be available. Some factors are temporary: dry eye can be treated, pregnancy is time-limited, and prescription instability may resolve with time. Other factors may indicate that a different procedure, such as LASIK, PRK, or ICL, would be more appropriate for your eye anatomy [S3].
Patients who are not candidates for any laser vision correction due to corneal thickness or shape concerns may still achieve reduced dependence on glasses through implantable lens procedures, which do not remove corneal tissue. Learn more about eye treatments available for various vision correction needs.
Action Checklist
Before Your Consultation
Gather your current eyeglass prescription and any previous prescription records if available. Bring a list of current medications, including over-the-counter drugs and supplements. Be prepared to discuss your medical history, including any systemic conditions, previous eye surgeries or injuries, and current eye symptoms such as dryness or irritation [S1].
Remove contact lenses before your evaluation appointment. Contact lenses can temporarily alter corneal shape and thickness measurements. Surgeons typically require patients to stop wearing soft contact lenses for at least one week and rigid gas-permeable lenses for several weeks before accurate measurements can be obtained [S1].
Questions to Ask During Evaluation
Ask about your specific measurements: What is your corneal thickness? Does your corneal topography show any irregularities? What is your estimated residual stromal bed after the procedure? Understanding your individual numbers helps you evaluate the surgical plan [S2].
Inquire about the surgeon's experience with SMILE specifically. Ask how many SMILE procedures they have performed and what their protocol includes for managing complications or touch-up procedures [S1].
Next Steps
If evaluation confirms candidacy and you decide to proceed, your surgeon will provide specific pre-operative instructions, typically including avoiding contact lenses, certain medications, and eye makeup before surgery [S1].
If you are not a candidate for SMILE, ask for a clear explanation of why and whether alternative procedures might be appropriate. Understanding the specific reason for non-candidacy helps you make informed decisions about next steps [S3].
For those considering their options, additional SMILE information is available in our resource hub.
Many patients who are not candidates for SMILE are excellent candidates for other procedures. The evaluation provides valuable information about your eye health regardless of which path you pursue.
If you're considering SMILE and would like support in arranging a consultation with experienced providers, we can help you explore your options.
