Am I a suitable candidate for LASIK refractive surgery?

LASIK Candidacy Assessment

You are a suitable candidate for LASIK if you meet specific anatomical, refractive, and health criteria—most critically: stable refraction for at least one year, normal corneal topography/tomography ruling out ectasia risk, adequate corneal thickness (ensuring residual stromal bed ≥250 μm), age ≥18 years, and absence of active ocular disease or systemic contraindications. 1

Essential Screening Requirements

Absolute Prerequisites

You must meet ALL of the following to be considered:

• Age ≥18 years with documented refractive stability 2
• Stable refraction for at least 12 months (no change >0.5 D) 1
• Normal corneal topography/tomography with no signs of keratoconus, ectasia, or irregular astigmatism 1
• Adequate corneal thickness: Central corneal thickness must allow for residual stromal bed ≥250 μm after accounting for flap thickness (typically 100-120 μm) plus ablation depth 1
• Percentage of Tissue Altered (PTA) <40%: Calculate as (Flap Thickness + Ablation Depth)/Central Corneal Thickness 1

Contact Lens Discontinuation Protocol

If you wear contact lenses, you must discontinue them before evaluation:

• Soft spherical lenses: 3 days to 2 weeks minimum 1
• Toric soft lenses or rigid lenses: Longer discontinuation period (often 2-4 weeks) with multiple visits to confirm refractive stability 1

This is critical because contact lens-induced corneal warpage can mimic ectatic conditions and lead to inaccurate measurements.

Absolute Contraindications (Disqualifying Factors)

You are NOT a candidate if you have any of the following:

• Keratoconus or corneal ectasia (most common exclusion reason at 34.3% of rejected candidates) 3
• Insufficient corneal thickness (second most common exclusion at 23.1%) 3
• Unstable refraction or progressive myopia 1, 2
• Active or recurrent uveitis requiring ongoing treatment 1, 2
• Uncontrolled autoimmune disease or immune-mediated conditions 1, 2
• Poorly controlled diabetes mellitus 2
• Severe dry eye unresponsive to treatment (3.7% of exclusions) 3, 2
• Pregnancy or lactation 1, 2
• Visually significant cataract (9.7% of exclusions) 3
• Uncontrolled glaucoma 1
• Corneal endothelial disease including Fuchs dystrophy 1

Relative Contraindications (Proceed with Caution)

These factors require careful evaluation and may favor alternative procedures:

• High myopia (>6.00 D): Less predictable outcomes, higher regression rates (10.5% of exclusions); consider phakic IOL instead 1, 3
• High hyperopia (>3.50 D): Greater loss of best-corrected visual acuity risk (3.7% of exclusions) 1, 3
• History of previous uveitis (even if controlled) 1, 2
• Functional monocularity 1
• Significant blepharitis or ocular surface disease 1
• Medications: Amiodarone, isotretinoin use 2
• Occupational considerations: If you require exceptional night vision (e.g., night driving, aviation), understand increased risk of glare/halos 1

Critical Risk Assessment: Ectasia Prevention

Abnormal topography is the single most significant risk factor for post-LASIK ectasia 1. Your surgeon must evaluate:

• Topographic/tomographic indices: Belin-Ambrosio enhanced ectasia display and similar screening tools 1
• Posterior corneal curvature: Posterior surface abnormalities indicate higher risk 1
• Risk factor clustering: Thin corneas + young age + high correction + thin residual bed = exponentially higher risk 1

Even with normal topography, PTA ≥40% significantly increases ectasia risk 1.

Refractive Range Considerations

Myopia (Nearsightedness)

• Low to moderate myopia (-1.00 to -6.00 D): Excellent predictability—86% within 1.00 D of target, 92% achieve 20/20 or better 1
• High myopia (>-6.00 D): More regression over time (-1.33 D over 10 years vs -0.10 D for low myopia); consider alternatives 1

Hyperopia (Farsightedness)

• Low hyperopia (0 to +3.50 D): 88% within 1.00 D of target 1
• High hyperopia (>+3.50 D): Less predictable, higher BCVA loss risk (up to 20%); less favorable outcomes 1

Astigmatism

Can be effectively treated with LASIK, but axis alignment is critical—misalignment significantly reduces effectiveness 1

Psychological and Expectation Screening

Your psychological readiness and realistic expectations directly impact satisfaction 1. You should NOT proceed if:

• You have unrealistic expectations about outcomes 1
• You have uncontrolled depression or anxiety (associated with decreased satisfaction even with good visual outcomes) 1
• You cannot accept the possibility of needing reading glasses after surgery (especially if presbyopic age) 1, 3

Special Populations

Presbyopic Patients (Typically Age >40)

You must understand and accept:

• Loss of near vision in myopes after correction 1
• Monovision option: One eye corrected for distance, one for near—requires trial with contact lenses first 1

Athletes/High-Risk Activities

If you box or engage in contact sports, PRK may be preferable to LASIK to avoid flap-related complications from trauma 4. Surface ablation eliminates flap displacement risk.

Common Pitfalls to Avoid

1. Proceeding with unstable refraction: Leads to residual refractive error requiring enhancement (6.3% retreatment rate) 1
2. Inadequate contact lens discontinuation: Results in inaccurate measurements and poor outcomes 1
3. Ignoring subtle topographic abnormalities: Leads to post-operative ectasia, the most devastating complication 1
4. Overlooking dry eye symptoms: Worsens significantly post-LASIK; treat aggressively pre-operatively 1, 2
5. Insufficient informed consent: You must understand night vision symptoms (glare, halos) may develop or worsen, especially with high corrections or large pupils 1

Alternative Procedures to Consider

If you're not an ideal LASIK candidate:

• PRK/surface ablation: Better for thin corneas, contact sports athletes, or borderline topography 1
• SMILE (Small Incision Lenticule Extraction): FDA-approved for -1.00 to -10.00 D myopia with -0.75 to -3.00 D astigmatism; preserves more anterior corneal strength 1, 5
• Phakic IOL: For high myopia (>-6.00 D) or high hyperopia with adequate anterior chamber depth 1, 6
• Refractive lens exchange: For presbyopic patients or those with early cataract 1, 3

The Bottom Line

Approximately 38.4% of refractive surgery consultation seekers are ultimately not candidates 3, with abnormal topography and insufficient corneal thickness being the leading reasons. Your candidacy depends on passing a comprehensive screening that prioritizes long-term corneal stability over immediate refractive correction. If you meet the anatomical and health criteria outlined above, LASIK offers excellent safety and efficacy with 92% achieving 20/20 vision or better for low-to-moderate myopia 1. However, if you have any absolute contraindications or multiple relative risk factors, alternative procedures or continued spectacle/contact lens wear may better serve your long-term visual health and quality of life.