Am I a Candidate for Laser Eye Surgery? A Self-Assessment Guide

Not everyone qualifies for laser eye surgery — and the procedure that's right for you depends on a combination of factors that no online quiz can fully evaluate. But you can get a reasonable sense of your candidacy before booking a consultation. Here's what surgeons actually assess and why each factor matters.

Age Requirements

Most surgeons require patients to be at least 18 years old, and many prefer 21 or older. The reason is simple: your prescription needs to be stable. Younger eyes are still changing, and performing a permanent correction on a moving target leads to regression. A stable prescription means your glasses or contact lens power hasn't changed by more than 0.50 diopters in the past 12 to 24 months.

There's no strict upper age limit for laser surgery, but patients over 40 should understand presbyopia — the gradual loss of near-focusing ability that affects everyone regardless of previous vision. LASIK can correct distance vision brilliantly but won't prevent the need for reading glasses. Monovision LASIK (correcting one eye for distance and one for near) is an option, but not everyone adapts to it comfortably.

Prescription Range

Each procedure has a treatment envelope — the range of prescriptions it can safely and effectively correct. Going beyond these ranges risks poor outcomes, regression, or complications.

LASIK and PRK work well for myopia (nearsightedness) up to about −8.00 diopters, hyperopia (farsightedness) up to +4.00, and astigmatism up to 5.00 diopters. SMILE handles myopia up to about −10.00 and astigmatism, but cannot yet correct farsightedness. ICL lenses cover the widest range — up to −20.00 for myopia and +10.00 for hyperopia — making them the only option for very high prescriptions.

If your prescription is borderline (say −7.50), an in-person evaluation becomes especially important. Corneal topography and thickness measurements determine whether there's enough tissue to safely correct that amount.

Corneal Thickness

This is the factor that disqualifies many otherwise-ideal candidates. LASIK requires sufficient corneal thickness because creating the flap consumes tissue, and then the laser ablation removes more. The average human cornea is about 540 microns thick. After accounting for the flap (roughly 100 to 120 microns) and the laser correction, at least 250 to 300 microns of residual stromal bed must remain to maintain corneal structural integrity.

Patients with corneas thinner than about 500 microns may be steered toward PRK (which doesn't require a flap, preserving that tissue) or ICL (which doesn't touch the cornea at all). Corneal thickness is measured during the pre-operative exam using a pachymeter — it's a painless, quick test.

Corneal Shape and Health

Corneal topography maps the curvature of your cornea in detail. Surgeons look for irregularities that could indicate keratoconus (a progressive thinning and cone-shaped bulging of the cornea) or other corneal dystrophies. Keratoconus is an absolute contraindication for LASIK and SMILE — the procedure would weaken an already compromised structure. Early-stage keratoconus can be subtle, which is why topography screening is non-negotiable before any refractive procedure.

Previous corneal scarring, certain infections, or severe dry eye disease may also affect candidacy. These conditions don't always disqualify you, but they need to be managed before surgery.

Dry Eye

This is one of the most common reasons for delayed or conditional candidacy. LASIK temporarily worsens dry eye because the flap creation severs corneal nerves that regulate tear production. If you already have significant dry eye, LASIK can make it considerably worse — sometimes permanently.

Mild dry eye can often be managed with a pre-treatment protocol of preservative-free artificial tears, omega-3 supplements, and sometimes punctal plugs. More severe cases may be better served by PRK (fewer nerve disruptions) or ICL (no corneal nerve disruption at all).

Pupil Size

Larger pupils (greater than about 7 mm in dim light) were historically associated with higher rates of halos and glare after LASIK, because the treatment zone might not fully cover the pupil when it dilates. Modern wavefront-guided and topography-guided treatments have largely solved this problem by creating larger treatment zones and smoother transition zones, but it's still worth measuring and discussing.

General Health Conditions

Certain systemic conditions affect healing and candidacy. Autoimmune diseases like lupus, rheumatoid arthritis, and Sjögren's syndrome can impair corneal healing and are generally considered contraindications, though mild, well-controlled cases may still qualify under close supervision. Uncontrolled diabetes can affect wound healing and retinal health. Pregnancy and nursing cause hormonal fluctuations that temporarily change corneal shape and prescription — surgeons will ask you to wait until several months after you've finished breastfeeding.

Medications that affect healing (particularly corticosteroids and immunosuppressants) need to be disclosed and discussed. Some medications, like isotretinoin (Accutane), should be discontinued for six months to a year before surgery due to their effects on corneal healing.

What Happens If You Don't Qualify for LASIK?

Failing a LASIK candidacy assessment isn't the end of the road — it's a redirection. Most patients who don't qualify for LASIK have an excellent alternative. Thin corneas often make you a great PRK candidate. Very high prescriptions point toward ICL. Even patients with early keratoconus may benefit from corneal cross-linking followed by a surface procedure once the cornea is stabilized.

The best way to know where you stand is a comprehensive evaluation with a surgeon who offers multiple procedure types. A surgeon who only performs LASIK may try to fit you into LASIK even when another procedure would serve you better. Seek a practice with the full range of options.