Quick Answer
LASIK does not “fail” in most cases — but undercorrection, overcorrection, or regression can result in vision that does not meet your pre-operative target. The retreatment (enhancement) rate across published studies is 1–5% over 10 years. Enhancement surgery — a second laser procedure to refine the outcome — successfully corrects residual refractive error in the majority of eligible patients. Serious, permanent vision loss from LASIK is extremely rare.
Detailed Explanation
“LASIK failure” is a term that encompasses a wide range of outcomes, from minor undercorrection requiring glasses for night driving to rare but serious complications that require significant medical management. Understanding the spectrum matters.
The most common reason for disappointing results: undercorrection
Undercorrection occurs when the laser removes slightly less tissue than needed to achieve the target refraction. It is most common in:
- High myopia (over -6.00 D), where tissue removal is greatest
- High astigmatism treatments
- Patients whose corneal response to healing differs from the predictive model
Mild undercorrection often means a patient achieves 20/25 or 20/30 instead of 20/20 — functional vision, but not the goal. This can typically be addressed with an enhancement procedure.
Overcorrection
Less common than undercorrection, overcorrection produces hyperopia (farsightedness) in a patient who was previously myopic. This can cause near blur and eye strain. Mild overcorrections often partially regress. More significant overcorrections can be retreated once the refraction stabilizes, typically at 3–6 months post-operatively.
Regression
Some patients experience a gradual return of myopia over months to years after LASIK. The laser treatment modifies the corneal stroma, but the eye can continue to elongate (axial myopia progression) independently of the cornea. Regression is more common in patients who were treated before their prescription fully stabilized — which is why prescription stability before surgery matters so much.
Enhancement (retreatment) surgery
If results fall short of the target and the eye anatomy supports it, a LASIK enhancement can be performed. The surgeon either:
1. Re-lifts the original flap (possible for years after the initial procedure in many cases) and applies additional laser treatment to the exposed stroma 2. Performs surface ablation (PRK) over the original LASIK site if the flap cannot be safely re-lifted or if corneal thickness is marginal
Enhancement rates in published literature vary:
- Studies from high-volume centers: 1–3% over 10 years
- Broader population studies: 3–5% over 10 years
- Higher prescription ranges: up to 10% over time
Most practices with lifetime enhancement programs will perform retreatment at no additional cost for eligible patients. Read the terms of any lifetime program carefully before signing — eligibility typically requires annual exams at the same practice, within a defined prescription range, and within a specified time window.
When enhancement is not possible
Not all patients who want an enhancement can have one. Limiting factors include:
- Insufficient residual corneal thickness. The cornea must retain adequate tissue after the first procedure. If enhancement would reduce stromal thickness below safe minimums, it cannot be performed safely.
- Corneal ectasia. This rare but serious complication involves progressive thinning and bulging of the cornea after LASIK, typically in patients with undetected subclinical keratoconus or insufficient residual stromal depth. Treatment options include rigid gas-permeable (RGP) lenses, corneal cross-linking (CXL), or — in advanced cases — corneal transplantation.
- Irregular corneal surface. Some complications produce irregular astigmatism that laser surgery cannot effectively treat.
Alternatives when enhancement is not viable
- Rigid gas-permeable (RGP) contact lenses can mask irregular astigmatism and corneal irregularity effectively
- Scleral lenses vault entirely over the cornea, providing clear vision regardless of corneal surface irregularity
- Phakic intraocular lenses (Visian ICL) can correct residual refractive error without touching the cornea
- Corneal cross-linking (CXL) halts progression of ectasia
- Corneal transplantation is reserved for severe, end-stage ectasia — an extremely rare outcome
LASIK Surgery Awards recognizes practices that are transparent about their enhancement rates and complication management protocols. A practice that tracks outcomes and discusses them honestly is one operating at a higher standard of care.
Important Considerations
“Failure” in most cases is correctable. The vast majority of outcomes that do not meet the initial target can be addressed with enhancement surgery or optical correction. Permanent, uncorrectable vision loss is exceedingly rare in properly screened patients.
Patient selection is the primary predictor. Most serious LASIK outcomes — including ectasia — are associated with patients who should not have had LASIK in the first place. Rigorous pre-operative screening is the most effective “treatment” for LASIK failure.
Manage expectations before surgery. Patients with very high prescriptions or significant astigmatism have a higher probability of needing an enhancement than those with lower prescriptions. A good surgeon discusses this probability honestly before proceeding.
The “lifetime guarantee” conversation is worth having. If a practice offers a lifetime enhancement program, clarify the specific terms in writing before your procedure. The value of this offer depends entirely on the conditions attached.
What to Do Next
1. If you are considering LASIK, ask your surgeon directly: “What is your practice’s enhancement rate?” A surgeon who tracks outcomes can answer this question. 2. If you have had LASIK and are disappointed with your results, schedule a post-operative consultation and request a current topography and refraction. This determines whether your result is stable and whether enhancement is anatomically possible. 3. If you are experiencing progressive vision changes years after LASIK, see a corneal specialist to rule out ectasia or other structural changes.
For a complete understanding of candidacy factors that predict success, see What Disqualifies You from Getting LASIK?.
Related Questions
Wondering whether retreatment is common enough to plan for? Read Can You Get LASIK Twice? for a detailed look at LASIK enhancement surgery.
Concerned about the most serious possible outcomes? See Can You Go Blind from LASIK? for a fact-based examination of LASIK’s most extreme risks.
Trying to find a surgeon whose outcomes data you can trust? Read How Do I Find the Best LASIK Surgeon Near Me? for a credential-first approach to surgeon selection.