SMILE vs PRK: compared, side by side
Both leave the surface of the eye intact in different ways: one through a small incision, one by removing the surface layer and letting it regrow. The first week is the main difference.
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Quick answer
SMILE removes a lenticule of tissue from inside the cornea through a small incision, leaving the outer surface untouched. PRK removes that outer surface layer and reshapes the tissue beneath it, then waits for the layer to regrow. Neither creates a flap, and the practical difference between them is concentrated in the first week.
General educational information about a subject, not an assessment of your own eyes. Suitability and treatment decisions are made by a qualified ophthalmologist who has examined you.
- Compared
- SMILE and PRK
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- Comparison
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- Related subjects
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Both avoid a flap, by different means: one works inside the cornea and takes the tissue out through a small incision, the other works from the outside in and lets the surface grow back.
| Category | SMILE | PRK |
|---|---|---|
| What is removed | A lenticule of tissue from inside the cornea | The outer surface layer, after which the excimer laser reshapes the tissue beneath |
| Number of lasers | One femtosecond laser | One excimer laser, and in the no-touch variant the surface is removed by the same laser |
| The first week | Vision is often usable within a day or two | Vision stays blurry until the surface has regrown, typically a matter of days |
| Corneal nerves | Fewer are cut than with a flap, though the incision still crosses some | The surface layer removed is itself richly supplied with nerves, and it regrows |
| Corneal thickness | Requires enough tissue for the lenticule and the remaining bed | Suits thinner corneas, because no flap is created and less depth is consumed |
| Enhancement | No flap exists, so a further treatment is usually a surface procedure | A repeat surface treatment is straightforward in principle |
The measurements support a lenticule of the required thickness and you want the recovery profile that comes with a small incision.
The cornea is thinner or its surface irregular, the prescription is one that surface ablation handles well, or a slower first week is an acceptable trade for avoiding any incision into the stroma.
Neither column is a recommendation. Which procedure suits you depends on measurements that can only be taken in a clinic, and a surgeon who tells you one option is right for everyone is describing their product, not your eyes.
SMILE vs PRK
These two are usually compared because both avoid the thing most patients have heard about: a flap. Each avoids it in a different direction. SMILE works inside the cornea and takes the tissue out through an incision of a few millimetres, so the outer surface is never lifted. PRK works from the outside in, removing the surface layer to reach the tissue underneath and letting that layer grow back on its own.
Because both leave the cornea without a flap, the comparison turns on the details that matter to a particular person: how much tissue each consumes, how the eye behaves during healing, and which prescriptions each is established for.
Two ways of leaving no flap
SMILE requires the cornea to be thick enough for the lenticule and for what remains beneath it, and it is established for short sightedness and myopic astigmatism. PRK consumes less depth because no flap is created at all, which is why it is still reached for where the cornea is thinner or its surface is irregular, and why it remains the fallback technique when a first procedure needs to be refined.
The trade is in the healing. An incision heals quickly and quietly; a removed surface layer has to regenerate, and regenerating tissue is the source of both the blur and the discomfort in the days after PRK.
What the first week is like
After lenticule extraction, most people have usable vision within a day or two, with a scratchy sensation rather than pain, and a visible line at the edge of the cornea that fades. After a surface procedure, vision remains blurred until the surface has regrown, and the eye is often uncomfortable enough that the clinic will plan the drops and the follow-up visits around it. Both settle, and both fluctuate while they do.
This is the one difference worth planning a calendar around. If you cannot spend several days with unreliable vision, the surface option is a poor fit for the timing even if it suits the eye.
Surface healing, haze and the sun
Regrowing surface tissue can produce a faint haze, more likely with higher prescriptions and with ultraviolet exposure during healing. That is why steroid drops and sunglasses are part of the treatment rather than advice, and why the follow-up schedule is not something to skip when everything feels fine.
Lenticule extraction does not carry that particular risk, and it carries the small-incision ones instead: the incision has to be placed, the lenticule has to be separated without tearing, and the technique depends more on the surgeon than a surface treatment does. Both sets of risks are uncommon, and both are discussed at the assessment.
Which one is considered for which eye
The honest answer is that the measurements decide, and that two surgeons can look at the same measurements and prefer different techniques without either being wrong. What is not a matter of preference is the arithmetic: corneal thickness, the shape of the surface, the prescription and the tear film together determine which procedures are even available.
Ask what each technique would leave behind in terms of corneal thickness, and ask what the plan would be if the result needed refining. Those two answers say more about a clinic than any comparison table, including this one.
- What would each technique leave of my cornea, in numbers?
- Which do you perform more often, and how often do you refine each?
- What is the plan and the cost if a refinement is needed?
Also known as smile vs prk, prk vs smile, transprk vs smile, smile compared with prk
Questions about SMILE vs PRK
Each answer below is the short version; the question links to the page that carries it in full, with sources.
- What is the difference between PRK and SMILE?
PRK removes the outer corneal layer and reshapes the surface, while SMILE removes a shaped piece of tissue from inside the cornea through a small incision. Both avoid a flap, and they differ mainly in recovery speed and in how the eye surface is left.
- Which procedure has the fastest recovery?
Flap and lenticule procedures generally settle more quickly than surface treatments, because the outer layer of the cornea is left intact. Beyond that the differences between individual procedures are smaller than the differences between individual patients.
- Which procedure causes less discomfort?
Surface treatments such as PRK are usually the most uncomfortable in the first few days, because the outer layer of the cornea regrows. Flap and lenticule procedures are generally reported as more comfortable early on.
All 104 SMILE questions, searchable
Where this is covered in full
- How SMILE works
Lenticule extraction explained: what the laser cuts, and what it removes.
- SMILE Pro compared with LASIK and PRK
The differences between the main refractive procedures, without declaring a winner.
Related subjects
- SMILE
Lenticule extraction: a lenticule is shaped inside the cornea and removed through a small incision, so there is no flap.
- PRK
Surface treatment: the outer layer of the cornea is removed and the tissue beneath it is reshaped, with no flap and no lenticule. The surface then regrows, which is why the first week is slower.
- TransPRK
A surface treatment in which the outer layer of the cornea is removed and the reshaping are done by the same laser pass, without a separate step and without touching the eye.
- Myopia (short sightedness)
The eye focuses light in front of the retina, so near objects are clear and distant ones are blurred. It is the refractive error most commonly treated with laser vision correction.
- Astigmatism
The cornea is curved unevenly, so light is focused differently across different axes and the blur is not the same in every direction. It commonly occurs alongside short or long sightedness.
- Laser eye surgery in the UAE
What is available across the emirates, what is the same everywhere in the country, and what genuinely varies between one licensed facility and another.
- How SMILE works
Lenticule extraction explained: what the laser cuts, and what it removes.
- SMILE Pro compared with LASIK and PRK
The differences between the main refractive procedures, without declaring a winner.
This page describes what is generally true about smile vs prk. It is not a diagnosis, and it cannot say whether a treatment is suitable for you, because suitability depends on measurements taken during an examination.
Sources & further reading
We prefer primary sources. Where a claim comes from a manufacturer, a single study or a regulator, it is labelled as such below.
- Small Incision Lenticule Extraction (SMILE) Clinical reference StatPearls, NCBI Bookshelf
A continuously updated clinical reference chapter covering SMILE indications, technique, outcomes and complications, written for clinicians.
Used for How the lenticule is created and removed; Indications and contraindications; Complication categories; Corneal biomechanics compared with flap-based surgery.
Link checked 22 September 2026
- Comparison of clinical outcomes of LASIK, Trans-PRK, and SMILE Peer-reviewed literature Peer-reviewed literature (via PubMed Central)
A comparative study of three commonly used refractive procedures, including a summary of proposed advantages of each.
Used for The procedure comparison page, particularly the PRK discussion.
Link checked 22 September 2026
- Dry eye and corneal sensitivity after small incision lenticule extraction: a meta-analysis Peer-reviewed literature Peer-reviewed literature (via PubMed Central)
A meta-analysis of corneal sensitivity and dry-eye measures after SMILE compared with femtosecond LASIK, generally finding faster recovery of sensation in the SMILE group in the early postoperative period.
Used for Corneal sensation and dry-eye timing discussions.
Link checked 22 September 2026
Guides that explain this
These pages go deeper on the questions that usually follow this one.