Introduction
PRK has been performed in the United States since FDA approval in 1995, making it one of the most thoroughly studied elective surgical procedures in modern ophthalmology. Decades of post-market surveillance, randomized controlled trials, military outcome studies, and independent registry data have produced a comprehensive safety and efficacy picture. That picture is overwhelmingly positive for appropriately selected patients treated by qualified surgeons.
Understanding PRK safety and outcomes requires distinguishing between what published evidence actually shows, what risks are real versus theoretical, and what variables most influence whether an individual patient achieves an excellent result. For patients researching refractive surgery, the ability to evaluate these factors critically is the difference between making a well-founded decision and acting on marketing.
This page reviews the clinical evidence on PRK safety and long-term outcomes, including efficacy rates, complication frequencies, known risk factors, and what separates high-performing surgical programs from average ones. Surgeons who consistently deliver outcomes at the high end of published benchmarks are recognized through the PRK Surgery Awards program.
PRK Efficacy: What the Evidence Shows
Visual Acuity Outcomes
The most fundamental measure of PRK success is uncorrected distance visual acuity (UDVA) — how well the patient sees without glasses or contact lenses after surgery.
Large published series and meta-analyses consistently show:
- Approximately 90 to 95% of myopic PRK patients achieve 20/20 or better uncorrected vision at one year. For mild to moderate myopia (up to -6.00 diopters), the rate of 20/20 or better frequently exceeds 95% in experienced hands.
- 85 to 95% of patients achieve 20/40 or better regardless of initial prescription range, meeting the legal driving standard.
- Approximately 70 to 80% of patients with higher myopia (-6.00 to -10.00 diopters) achieve 20/20 or better, with outcomes slightly lower as correction magnitude increases.
These figures reflect outcomes across a wide population of surgeons and practices. Top-performing centers with experienced surgeons, modern wavefront-guided platforms, and rigorous patient selection consistently produce results at the upper end of these ranges.
U.S. Military PROWL Trials
The PROWL (Patient-Reported Outcomes with LASIK) study and its parallel PRK analysis represent some of the most rigorous prospective outcome data collected in refractive surgery. These trials, conducted at military medical centers with active-duty service members, evaluated not just visual acuity but patient-reported outcomes — visual symptoms, satisfaction, and quality of life measures.
Key findings from the PRK arm:
- At three months post-operatively, approximately 85% of PRK patients reported that their vision met or exceeded expectations.
- At 12 months, satisfaction rates between PRK and LASIK cohorts were equivalent, despite LASIK patients having faster early recovery.
- PRK patients reported slightly higher rates of visual symptoms (halos, glare, difficulty with night driving) at one month but equivalent rates at 12 months compared to LASIK.
This data is particularly meaningful because military subjects represent physically fit, thoroughly screened candidates — arguably an ideal population — and the procedures were performed by experienced military ophthalmologists.
Long-Term Refractive Stability
Refractive stability is a measure of how well the correction holds over time. Some degree of regression — a gradual return toward the pre-operative prescription — can occur in both PRK and LASIK, particularly at higher correction levels.
For PRK:
- The majority of patients with corrections up to -6.00 diopters demonstrate excellent refractive stability at five, ten, and fifteen-year follow-up intervals.
- Higher corrections (greater than -6.00 diopters) carry a higher regression risk, with some studies showing meaningful regression in 10 to 20% of high myopes over a ten-year period.
- Hyperopic PRK carries greater regression risk than myopic PRK, a pattern consistent across laser refractive procedures.
When regression is clinically significant, enhancement PRK is typically a viable option if sufficient corneal tissue remains, provided the eye has been stable for at least six months.
PRK Complication Profile
A complete safety assessment requires understanding what complications occur, how frequently, and how they are managed.
Corneal Haze
Corneal haze — a superficial opacity in the anterior stroma — was the most significant complication of early PRK before mitomycin-C became standard. In the pre-MMC era, clinically significant haze occurred in approximately 2 to 5% of myopic PRK cases and higher rates in higher prescriptions.
With routine MMC application at the time of surgery, the rate of clinically significant haze has fallen to less than 1% in most published series. Mild, transient haze visible only on slit-lamp examination is more common but resolves without clinical consequence in the vast majority of cases.
The surgeon’s MMC protocol — concentration, duration of application, and thoroughness of irrigation — is a meaningful quality variable. Leading surgeons use evidence-based protocols and individualize MMC exposure based on the ablation depth.
Undercorrection and Overcorrection
No refractive procedure achieves perfect target accuracy in 100% of cases. Some degree of residual refractive error is expected and does not represent surgical failure.
- Undercorrection: More common in higher prescriptions. If the residual prescription is clinically significant and the eye has stabilized, enhancement is typically offered.
- Overcorrection: More common in hyperopic PRK. Overcorrection producing myopia in a previously hyperopic patient can be disorienting and may require enhancement if it does not resolve with regression over several months.
Most centers report 80 to 90% of eyes within ±0.50 diopters of the intended correction at one year. Within ±1.00 diopter, the figure typically exceeds 95%.
Infection (Microbial Keratitis)
Post-operative infection is a rare but serious complication of any ocular surgery involving surface exposure. PRK, which involves direct stromal exposure for three to five days under a bandage contact lens, carries a theoretical infection risk during this window.
Published rates of microbial keratitis following PRK are very low — approximately 1 in 2,000 to 1 in 5,000 cases — and most cases are mild and respond to topical antibiotic treatment. Severe infections causing permanent vision loss are exceedingly rare. Prophylactic topical antibiotics during the first week effectively suppress this risk.
Regression
As described above, regression is more likely with higher corrections. It should be conceptualized not as a failure but as a biological tendency that can be anticipated, monitored, and addressed with enhancement if clinically indicated. Top surgeons counsel patients about regression risk upfront when treating high prescriptions rather than treating it as an unexpected complication.
Dry Eye
PRK affects corneal nerve density less extensively than LASIK due to the absence of a lamellar cut, but some temporary reduction in corneal sensitivity is expected after any refractive procedure. This can manifest as dry eye symptoms — burning, foreign body sensation, fluctuating vision — that typically resolve within three to six months as corneal nerve regeneration occurs.
Patients with pre-existing dry eye require careful pre-operative evaluation. See PRK Candidacy: When PRK Is the Better Choice for a discussion of how dry eye affects candidacy.
Ectasia
Post-refractive ectasia — progressive corneal thinning and bulging following surgery — is one of the most serious complications of refractive surgery. In LASIK, it occurs in approximately 1 in 500 cases, with the majority attributable to pre-operative keratoconus or forme fruste keratoconus that was not identified.
In PRK, ectasia is significantly rarer because the absence of a flap preserves more stromal integrity. Some experts argue that PRK is inherently safer with respect to ectasia risk for borderline candidates precisely because the biomechanical disruption is less severe. However, PRK on a cornea with active or advanced keratoconus is still contraindicated.
How Top PRK Programs Achieve Superior Outcomes
The best PRK outcomes are not accidental. They result from systematic quality practices across every phase of the surgical episode.
Pre-Operative Screening Rigor
As discussed in candidacy pages, comprehensive pre-operative screening is the most important safety intervention in refractive surgery. Identifying and declining inappropriate candidates prevents the vast majority of serious complications. Top programs invest in the full battery of diagnostic equipment — Scheimpflug tomography, anterior segment OCT, wavefront aberrometry, and sophisticated tear film analysis — and interpret results conservatively.
Wavefront-Guided and Topography-Guided Ablation
Modern laser platforms with wavefront-guided or topography-guided profiles produce measurably better optical quality outcomes than conventional ablation. Studies comparing wavefront-guided to conventional LASIK and PRK consistently show higher rates of 20/16 or better vision and lower rates of patient-reported optical symptoms with guided treatments.
Top PRK surgeons use these platforms as standard, not as a premium upsell.
Surgeon Volume and Specialization
Volume matters in refractive surgery. Surgeons who perform PRK regularly — at least several hundred procedures annually — develop the pattern recognition to identify atypical healing responses, optimize ablation profiles, and counsel patients through unusual recovery trajectories. Occasional PRK performers, regardless of their credentials in other surgical domains, lack this experiential depth.
The PRK Surgery Awards evaluation specifically examines annual surgical volume as a component of the recognition criteria.
What Patients Should Understand About PRK Safety
PRK is one of the most studied elective surgeries performed today: Over 30 years of published outcomes data supports its efficacy and safety profile in appropriately selected patients. The risk of serious, vision-threatening complications from PRK is lower than the cumulative risk of long-term contact lens wear for most patients.
Your outcomes depend significantly on your candidacy and your surgeon: Average published outcomes represent the full range of surgeons and patients. In the hands of an experienced, well-equipped PRK specialist operating on an ideal candidate, outcomes at the top of published ranges are the expectation, not the exception.
Complications are manageable when detected early: Most PRK complications — haze, undercorrection, regression — are detected through structured follow-up and addressed with established treatment protocols. This is why post-operative follow-up adherence matters.
For a specific comparison of PRK and LASIK risk profiles, see PRK vs LASIK: A Comprehensive Comparison and PRK Risks and How Top Surgeons Mitigate Them.
Frequently Asked Questions
What is the PRK surgery success rate? In appropriately selected patients treated by experienced surgeons, 90 to 95% achieve 20/20 or better uncorrected vision. Patient satisfaction rates at one year consistently exceed 90% in published studies.
Can PRK cause blindness? Serious, vision-threatening complications from PRK are exceedingly rare when proper candidacy screening is performed. The risk of permanent significant vision loss from PRK is estimated at less than 1 in 50,000 procedures in experienced hands — lower than the risk associated with long-term extended contact lens wear.
How long do PRK results last? For most patients with mild to moderate prescriptions, PRK results are permanent. Some regression occurs over years with higher prescriptions, but the majority of the correction holds. Long-term follow-up studies at 10 and 15 years show maintained outcomes for most patients.
What happens if PRK doesn’t fully correct my vision? If clinically significant residual refractive error remains after the eye has stabilized, an enhancement procedure is typically offered. Enhancement involves a new surface ablation to the cornea and is generally straightforward when adequate residual corneal tissue exists.
Is PRK safe for people over 50? Yes, with appropriate evaluation and counseling. Older patients need specific discussion about presbyopia management, as PRK corrects distance vision without addressing the age-related loss of near focus. Overall healing may be slightly slower in older patients, but outcomes are generally comparable.
Next Steps
PRK has an exceptionally strong safety and efficacy record built on three decades of clinical practice and research. For patients seeking the highest probability of an excellent outcome, the starting point is identifying a surgeon who performs PRK at the top of the field. Consult the PRK Surgery Awards directory for a vetted list of PRK specialists recognized for clinical excellence and outcome quality in your area.