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- Will Vision Be 6/6 (20/20) After LASIK? What the Evidence Says
Will Vision Be 6/6 (20/20) After LASIK? What the Evidence Says
Most people reach 6/6 (20/20) vision or better without glasses after LASIK, but it is not guaranteed. A review of 97 studies covering 67,893 eyes found 90.8% saw 20/20 or better, and the American Academy of Ophthalmology says about 9 in 10 patients end up between 20/20 and 20/40. Your result depends on your prescription, corneas and tear film, which your surgeon checks before treatment.
What does 6/6 (20/20) vision actually mean?
6/6 and 20/20 are the same result written in two units: 6/6 uses metres and 20/20 uses feet. If you have 6/6 vision, you can read at 6 metres (20 feet) the line of letters that an average person can read at that distance. The American Academy of Ophthalmology (AAO) says outside the United States eye-care providers use metres, with 6/6 as the equivalent goal.
Two things are worth knowing before you ask whether LASIK will give you 6/6.
- 6/6 is a measure of distance sharpness only. It says nothing about reading vision, contrast, night vision or comfort.
- It is not perfect vision. The AAO states that 20/20 is not perfect vision, and that sharper vision, such as 20/15 (6/4.5), is possible. It also reports that about 35% of adults see 20/20 naturally and about 75% reach it with glasses, contact lenses or surgery.
So the realistic question is not "will I see perfectly?" but "how likely is it that I will see as sharply without glasses as I do with them today, and what could stop that?" The rest of this guide answers both.
Will vision be 6/6 (20/20) after LASIK?
For most people, yes: the large majority of modern LASIK patients see 6/6 or better without glasses. The best summary of modern results is a review of LASIK studies published between 2008 and 2015 (97 studies, 67,893 eyes), led by Sandoval and colleagues. Its main findings:
| Result after modern LASIK | Figure in the review |
|---|---|
| Uncorrected vision 20/20 (6/6) or better | 90.8% of eyes |
| Uncorrected vision better than 20/40 (6/12) | 99.5% of eyes |
| Final prescription within ±0.5 dioptres of the target | 90.9% of eyes |
| Final prescription within ±1.0 dioptre of the target | 98.6% of eyes |
| Lost 2 or more lines of best-corrected (with-glasses) vision | 0.61% of eyes |
| Patient dissatisfaction | 1.2% |
Other authorities agree on the picture. The AAO says about 9 out of 10 people who have LASIK end up with vision between 20/20 and 20/40 without glasses or contact lenses. The US Food and Drug Administration (FDA) gives the other side: only a certain percentage of patients achieve 20/20 without glasses or contacts, and you may still need glasses or contact lenses after surgery, even if you needed only a very weak prescription before.
How to read these numbers. They are averages across many surgeons, lasers and prescriptions. They are published results, not a promise for your eyes, and none of them is a guarantee of 6/6. An individual's chance depends on factors your surgeon can measure, covered below.
How long until vision is clear after LASIK?
Most people notice sharper vision within hours or days of LASIK, but it can fluctuate for a few weeks and the final result is judged once healing has settled. The speed differs by method.
| LASIK / Femto-LASIK | SMILE / SMILE Pro | PRK / no-touch surface laser | |
|---|---|---|---|
| How quickly vision improves | Fastest: usually within days | Intermediate: usually a few weeks to settle | Slowest: vision is often about 20/30–20/50 when the bandage lens comes off at day 4–5, and it improves over 4–6 weeks |
| When the result is usually stable | Usually by about 3 months | Usually by about 3 months | About 3–6 months |
| What you may notice meanwhile | Dryness and changing sharpness during the day | Dryness, usually milder than after LASIK | Surface discomfort for the first days, then gradual sharpening |
Sources: EyeWiki (PRK timeline and stability; LASIK refractive stability usually by 3 months) and a 2022 comparison of LASIK, Trans-PRK and SMILE (speed of recovery). Your own timeline may differ.
Fluctuating vision in the early weeks is usually a sign of a drying, healing surface rather than a poor result. That is why your surgeon waits until the prescription is stable, typically around 3 months, before judging whether you have reached 6/6 or need a fine-tuning treatment.
Why do some people not reach 6/6 after LASIK?
Roughly 1 in 10 eyes ends up below 20/20 without glasses, and the cause is usually one of the following.
A small leftover prescription
Undercorrection is the most common refractive complication after a first LASIK treatment, according to EyeWiki, the AAO's clinical encyclopedia. Even a small residual prescription can drop an eye from 6/6 to the next line down the chart.
A larger starting prescription
The higher the initial correction, the harder it is to land exactly on target. A 2003 study of 2,485 eyes found that higher initial corrections, astigmatism and older age were linked to a greater chance of needing a second treatment.
Astigmatism and long-sightedness
The FDA warns that if you are long-sighted, the improvement in your vision may decrease with age.
Dry eye and a healing surface
A patchy tear film blurs vision on and off, even when the cornea itself has been reshaped correctly.
Corneal shape or health
Thin corneas or early keratoconus are reasons your surgeon may advise against LASIK. The rare complication ectasia, a weakening and bulging of the cornea, is described by EyeWiki as the most feared long-term complication and is linked to abnormal corneal maps before surgery, thin corneas and high short-sightedness.
Eye conditions unrelated to the laser
The AAO lists cataracts affecting vision and corneal disease among conditions that make LASIK unsuitable, because the laser cannot fix what limits the eye elsewhere.
The good news is that many of these can be found before surgery, and some can be treated after it.
Will LASIK vision stay 6/6 for life?
Not necessarily: laser correction is long-lasting, but it does not stop your eyes changing as you age. Three things can change your sharpness over the years.
- Regression. EyeWiki cites a 12-year follow-up in which most eyes showed about 10% myopic regression over time. Risk factors include higher starting prescriptions, younger age and thinner corneas.
- Reading vision. The AAO states LASIK cannot correct presbyopia, the age-related loss of close-up focus. Most people with excellent distance vision will need reading glasses around the age of 40, whether or not they have had surgery.
- Long-sightedness. The FDA notes that if you are long-sighted, the improved vision you gain after surgery may decrease with age.
If you are approaching 40 or older, ask your surgeon whether laser is the right operation for your age. Our guide Why not laser after 45? Laser vs lens surgery by age explains when lens surgery makes more sense.
Will I still need glasses after LASIK?
Many people never need distance glasses again, but some still use glasses for particular tasks. The AAO says LASIK allows most daily activities without corrective lenses, although some people need glasses for specific tasks such as reading or night driving.
| Situation | What usually happens |
|---|---|
| You reach 6/6 or better | No glasses for distance |
| You are over about 40 | Reading glasses are likely, because presbyopia is not treated by standard LASIK (AAO) |
| A small prescription remains | A light pair of glasses for driving or night vision, or a fine-tuning treatment (see below) |
| You choose monovision | One eye is set slightly short-sighted for reading and the other for distance. The AAO notes it is not suitable for everyone, so your surgeon can explain whether it fits you |
| Your prescription changes years later | Glasses, or in some cases a repeat treatment |
Does it matter whether I choose LASIK, SMILE or PRK?
For the chance of reaching 6/6, the differences between modern laser methods are small. They differ more in recovery, comfort, dry eye and suitability.
| Comparison | What the research found |
|---|---|
| LASIK vs PRK | A Cochrane review of 13 randomised trials (1,135 participants) concluded that results at one year were comparable. LASIK gave faster visual recovery and was less painful. The review rated its evidence as low quality. |
| SMILE vs femtosecond LASIK | A meta-analysis of 12 studies (1,076 eyes) found no significant difference in the proportion reaching 20/20 or better at 3–6 months, and dry-eye symptoms favoured SMILE. The evidence was rated low to very low quality. |
| All major laser methods | A network meta-analysis of 48 randomised trials found no significant difference in uncorrected vision between methods. Femtosecond LASIK was the most predictable at hitting the intended prescription. |
What this means for you: pick the method your surgeon recommends for your eyes, not the one with the best reputation. SMILE is approved in the US for short-sightedness from −1 D to −8 D with astigmatism up to −0.5 D (EyeWiki), so it does not suit every prescription. PRK suits thinner corneas. At Laser Istanbul Clinic, Prof. Dr. Ahmet Satıcı and Op. Dr. Aysan Bayram choose the method only after measuring your eyes.
What if my vision is not 6/6? Can LASIK be repeated?
Often yes: a small leftover prescription can usually be improved with a second laser treatment, called an enhancement, once your eyes are stable. The AAO says under- or over-correction can often be improved with glasses, contact lenses or additional laser surgery, and the FDA cautions that additional treatment may not be possible in every case.
- When: EyeWiki notes refractive stability typically occurs by 3 months, and enhancement is considered only after stability is documented.
- How often: in a 2003 study of 2,485 eyes, about 1 in 10 (10.5%) had a retreatment within a year, and 85% of retreatments happened within the first year. That study used older technology, so treat it as a rough guide, not a current rate.
- After SMILE: retreatment options are more limited, and a repeat treatment may require PRK (EyeWiki).
- Enough cornea: a repeat treatment depends on having enough corneal tissue left, which your surgeon measures.
If you are told your eyes need a repeat treatment, ask whether it is included in your quote. Our coordinator can confirm what is covered for your treatment before you book.
How can you improve your chances of seeing 6/6?
You cannot control every factor, but these steps make the most of the ones you can.
Have a thorough pre-operative examination
Corneal thickness and shape scans, pupil size, tear film and the back of the eye are checked before anyone recommends laser.
Have a stable prescription
The AAO advises a stable prescription for at least one year, and the FDA says no lasers are approved for LASIK under the age of 18.
Treat dry eye and eyelid problems first
The FDA notes dry eyes typically worsen after LASIK, so controlling them beforehand matters.
Be realistic about your prescription
Higher prescriptions and astigmatism carry more risk of missing the target.
Accept "no" when it is the right answer
The AAO lists unstable prescriptions, thin corneas, keratoconus and severe dry eye among reasons that rule LASIK out. Alternatives such as PRK, SMILE or an implantable lens may suit you better.
Follow your aftercare
Use drops as prescribed and attend your check-ups, so any problem is found while it is easy to fix.
At Laser Istanbul Clinic, laser surgery is led by Prof. Dr. Ahmet Satıcı and Op. Dr. Aysan Bayram. Corneal screening questions, such as a suspected keratoconus, can involve Doç. Dr. Muhammet Derda Özer (Doç. means Associate Professor), who specialises in the cornea. Surgery takes place in a fully equipped, Ministry of Health–licensed operating theatre in Istanbul.
Not sure whether your prescription and corneas are suitable? Send your prescription and any scans through our free online consultation and a surgeon will tell you honestly what to expect.
Frequently asked questions
Most likely, but it is not guaranteed. In a review of 97 studies covering 67,893 eyes, 90.8% of eyes saw 20/20 (6/6) or better without glasses, and 99.5% saw better than 20/40. That leaves roughly 1 in 10 eyes below 6/6 without glasses, which is why a pre-operative examination matters.
Yes. 6/6 is the metric version, measured in metres, and 20/20 is the version measured in feet. Both mean you can read at that distance what an average eye reads. According to the AAO, 20/20 is not perfect vision: some people see 20/15 (6/4.5) or better.
About 9 in 10. The Sandoval review reports 90.8% of eyes at 20/20 or better, and the AAO says about 90% of patients end up between 20/20 and 20/40 without glasses or contact lenses. Figures vary with prescription, method and surgeon.
Many people see much better within a day or two, but vision can fluctuate for a few weeks, and the final result is usually judged around 3 months. After PRK, vision takes longer: improvement continues for 4–6 weeks and the correction is usually stable by 3–6 months.
If you are around 40 or older, probably yes. LASIK does not treat presbyopia, the age-related loss of close focus, and most people with good distance vision need reading glasses around 40 whether or not they have surgery, says the AAO. Monovision is an option for some people, if your surgeon thinks it suits you.
LASIK is not temporary, but some regression can occur. A 12-year follow-up cited by EyeWiki found about 10% myopic regression over time in most eyes. Regression is more likely with higher prescriptions and younger patients, and long-sighted patients may see their benefit fade with age, according to the FDA.
Often, once your prescription has been stable, which usually means around 3 months. In a 2003 study, 10.5% of eyes were retreated within a year. Repeat treatment depends on your corneal thickness and is not possible for everyone.
No method is proven to give a clearly better chance of 6/6. A network meta-analysis of 48 randomised trials found no significant difference in uncorrected vision between the major laser methods. The methods differ in recovery speed, dry eye and which prescriptions they can treat.
Usually not: most health systems treat laser vision correction as elective, and the FDA notes most insurance does not cover LASIK. Our guide Does insurance pay for laser eye surgery? explains how the NHS, German statutory insurance, Dutch and French insurers handle it.
Thinking about laser eye surgery and want to know what to expect for your eyes?
Your surgeon at Laser Istanbul Clinic measures your corneas, pupils, tear film and prescription before recommending LASIK, SMILE Pro or PRK, and tells you honestly if laser is not right for your eyes. Laser surgery is led by Prof. Dr. Ahmet Satıcı and Op. Dr. Aysan Bayram.
Sources for the facts on this page
- Sandoval HP, Donnenfeld ED, Kohnen T, Lindstrom RL, Potvin R, Tremblay DM, Solomon KD. Modern laser in situ keratomileusis outcomes. Journal of Cataract & Refractive Surgery 2016;42:1224–1234. PMID 27531300. https://pubmed.ncbi.nlm.nih.gov/27531300/ ; summary with the 90.8% figure: Ophthalmology Times, https://www.ophthalmologytimes.com/view/what-literature-review-says-about-modern-lasik
- American Academy of Ophthalmology. LASIK — Laser Eye Surgery. https://www.aao.org/eye-health/treatments/lasik
- American Academy of Ophthalmology. What does 20/20 vision mean? https://www.aao.org/eye-health/tips-prevention/what-does-20-20-vision-mean
- US Food and Drug Administration. LASIK: What are the risks and how can I find the right doctor for me? https://www.fda.gov/medical-devices/lasik/what-are-risks-and-how-can-i-find-right-doctor-me
- US Food and Drug Administration. When is LASIK not for me? https://www.fda.gov/medical-devices/lasik/when-lasik-not-me
- EyeWiki (AAO). LASIK Complications. https://eyewiki.org/LASIK_Complications
- EyeWiki (AAO). Photorefractive Keratectomy. https://eyewiki.org/Photorefractive_Keratectomy
- EyeWiki (AAO). Small Incision Lenticule Extraction (SMILE). https://eyewiki.org/Small_Incision_Lenticule_Extraction_(SMILE)
- Shortt AJ, Allan BD, Evans JR. Laser-assisted in-situ keratomileusis (LASIK) versus photorefractive keratectomy (PRK) for myopia. Cochrane Database of Systematic Reviews 2013. PMID 23440799. https://pmc.ncbi.nlm.nih.gov/articles/PMC11848121/
- Shen Z, Shi K, Yu Y, Yu X, Lin Y, Yao K. Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis. PLoS One 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC4930219/
- Wen D, McAlinden C, Flitcroft I, et al. Postoperative Efficacy, Predictability, Safety, and Visual Quality of Laser Corneal Refractive Surgery: A Network Meta-analysis. American Journal of Ophthalmology 2017;178:65–78. PMID 28336402. https://pubmed.ncbi.nlm.nih.gov/28336402/
- Hersh PS, Fry KL, Bishop DS. Incidence and associations of retreatment after LASIK. Ophthalmology 2003;110(4):748–754. PMID 12689897. https://pubmed.ncbi.nlm.nih.gov/12689897/
- Chang JY, Lin PY, Hsu CC, Liu CJ. Comparison of clinical outcomes of LASIK, Trans-PRK, and SMILE. Journal of the Chinese Medical Association 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC12755589/