Vision correction: questions, page 4
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LASIK, SMILE, SMILE Pro, Femto LASIK, PRK and TransPRK explained, including how each one reshapes the cornea, what each can correct, and the honest comparison between them: which one suits a particular eye is a measurement question, not a preference.
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Vision correction & laser eye surgery questions and answers
Vision correction
LASIK, SMILE, SMILE Pro, Femto LASIK, PRK and TransPRK explained, including how each one reshapes the cornea, what each can correct, and the honest comparison between them: which one suits a particular eye is a measurement question, not a preference.
SMILE Pro 12
The ZEISS platform generation, the VISUMAX 800, and what the naming covers.
What does SMILE Pro correct? Answer
Short sightedness and myopic astigmatism. Lenticule extraction is established for those two, and long sightedness is not a routine indication on the platforms in general use.
So a SMILE Pro treatment is planned from two numbers: how short sighted you are, and how much astigmatism you have and at what axis. Both are measured during the assessment rather than taken from your glasses prescription, which is a different measurement taken under different conditions.
What this depends on
- The amount of short sightedness and astigmatism
- Corneal thickness and shape
- Whether your prescription has been stable
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Does SMILE Pro need an excimer laser? Answer
No. Lenticule extraction uses one laser, a femtosecond laser, to create the lenticule and the small incision; there is no second laser and no excimer step, which is one of the structural differences from a flap procedure.
What this depends on
- Which platform the clinic has installed
- Whether the clinic performs both types of procedure
- What the quote itemises for the technology used
Sources ZEISS Medical Technology , StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
What is the small incision in SMILE? Answer
It is the opening the surgeon uses to reach and remove the lenticule. The cornea stays intact apart from it, which is what the word flapless describes. The incision is a cut: describing it as keyhole surgery explains where the surgeon works, not how much tissue is involved.
What this depends on
- The size of the incision the surgeon plans
- How the wound heals in your case
- Whether you follow the early aftercare instructions
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
How do I know if a clinic offers SMILE Pro? Answer
By asking which laser platform is installed rather than which procedure name the website uses. The two are performed on different generations of the same machine, so the platform identifies the treatment unambiguously in a way the word “Pro” does not.
A clinic that can name its platform, say when it was installed and who services it is answering a question that can be checked. A clinic that answers only in brand language is not, and that difference is worth more than the price difference between two quotes.
What this depends on
- The platform name and when it was installed
- Which surgeon operates it, and how often
- Whether the clinic quotes the two generations at different prices
Sources ZEISS Medical Technology
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
What are the disadvantages of SMILE Pro? Answer
It is available at fewer clinics, it is not used for long sightedness, enhancement after it is a different procedure from lifting a flap, and the evidence comparing platform generations is still developing. None of those makes it a worse choice; they make it a choice with different trade-offs.
The honest framing is that both SMILE and LASIK have a list of trade-offs and neither list is empty. A clinic that presents only the advantages of the procedure it sells is describing a product, and the assessment is where the difference should appear.
What this depends on
- Whether your prescription is inside the treatable range
- Whether an enhancement might be needed and how it would be done
- Which procedure the surgeon performs most often
Sources StatPearls, NCBI Bookshelf , Peer-reviewed literature (via PubMed Central)
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Is SMILE Pro more expensive than LASIK? Answer
Often it is quoted higher, and the reason is the platform rather than the difficulty of the surgery. What matters more than the difference between the two totals is whether each quote covers the same things: the assessment, medication, the follow-up visits and any agreed policy on enhancement.
What this depends on
- Whether the quote is per eye or for both eyes
- Which tests and follow-up visits are included
- What the clinic’s enhancement policy is
Sources Dubai Health Authority
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Can SMILE be performed on a thin cornea? Answer
It can be suitable in some corneas where a flap would remove more tissue than a surgeon is comfortable with, and it is not a way around the problem: every refractive procedure removes tissue, and the amount required is what decides whether an eye is treatable.
What this depends on
- The measured corneal thickness and the depth the treatment needs
- Whether the topography is normal
- What your surgeon’s own limits are
Sources StatPearls, NCBI Bookshelf , StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Why is SMILE less widely available than LASIK? Answer
Because it requires a specific platform, the training that goes with it, and a surgeon who performs it often enough to stay current. A clinic offering many laser procedures will offer LASIK before it offers lenticule extraction.
That is a practical reason rather than a quality judgement in either direction, and it is why availability is not evidence of suitability. The question for your eyes is which procedure your measurements support and who performs it regularly.
What this depends on
- Which clinic near you has the platform
- How much of the surgeon’s practice is lenticule extraction
- Whether you are willing to travel for a specific surgeon
Sources StatPearls, NCBI Bookshelf , ZEISS Medical Technology
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
How experienced should a SMILE surgeon be? Answer
Experienced in this procedure specifically, which is a different question from how long they have been an ophthalmologist. Lenticule extraction has a learning curve that is not identical to flap surgery, so the relevant number is how many of these they perform and how often.
What this depends on
- The volume of lenticule procedures the surgeon performs
- Whether they can describe how they handle a difficult case
- Whether the person who assesses you is the person who operates
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Does the eye get held still during SMILE? Answer
Yes. During the laser step the eye is held against a curved interface, which is the pressure sensation most patients describe, and the platform tracks the eye while it works. The surgeon pauses or stops if the eye cannot be held in position.
Knowing that part of the sequence is expected is the single most useful thing for a nervous patient: a pressure sensation and temporarily grey or darkened vision during the laser step are reported commonly, and both are predictable rather than a sign that something has gone wrong.
What this depends on
- Your ability to keep looking at the fixation light
- The clarity of the interface against your cornea
- What the clinic explains to you beforehand
Sources Cleveland Clinic (YouTube) , StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
What happens to the lenticule that is removed? Answer
It is discarded as surgical tissue after removal. Because the lenticule is a shaped piece of cornea, researchers have explored reusing donated lenticules for other purposes, but that is experimental work and not part of routine care.
What this depends on
- What the clinic’s own policy is
- Whether the tissue is retained for any research purpose
- Whether you are asked to consent to anything of the kind
Sources US National Library of Medicine , StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Can SMILE be performed after LASIK? Answer
Usually not. A cornea that has already had a flap procedure has less tissue and a different structure, and lenticule extraction assumes an intact cornea. Where a residual prescription after LASIK is treated, a surface treatment or a flap lift is the more usual route.
What this depends on
- How much tissue was removed the first time
- The size and direction of the residual prescription
- Whether the original flap and its measurements are documented
Sources StatPearls, NCBI Bookshelf , StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
PRK & TransPRK 8
Surface treatment with no flap and no lenticule, and a slower first week.
Can PRK be repeated? Answer
A further surface treatment is possible in selected cases, provided there is enough corneal tissue left and the reason for the residual prescription is understood. It is not automatically offered, and the decision rests on the same measurements that decided the first treatment.
What this depends on
- How much corneal tissue remains
- Whether the residual prescription has stabilised
- Whether the first result was limited by healing or by planning
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Can PRK correct astigmatism? Answer
Yes. Surface treatment can correct astigmatism as well as short sightedness and long sightedness, and the ablation is shaped to the amount and axis of your astigmatism.
What this depends on
- How regular the astigmatism is
- The size of the prescription
- Whether the axis is stable between visits
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
What is the difference between PRK and TransPRK? Answer
Both are surface treatments. In PRK the outer corneal layer is removed first and the excimer laser then reshapes the tissue underneath. In TransPRK, the laser itself removes that layer and performs the reshaping in one continuous step, without alcohol or a blade.
Whether the single-step version produces a different outcome is a question clinicians still answer differently, and a clinic’s preference is usually about the platform installed and how the surgeon was trained. What both share, and what matters most to a patient, is the slower first week compared with a flap or lenticule procedure.
What this depends on
- Which platform the clinic has
- Which technique the surgeon performs regularly
- Whether either approach is unsuitable for your cornea
Sources Peer-reviewed literature (via PubMed Central)
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
When can I swim after PRK? Answer
Swimming and other water exposure are restricted until the surface of the eye has healed and your surgeon says so. The restriction is usually longer after surface treatment than after a flap or lenticule procedure, because the outer layer is regrowing.
What this depends on
- How quickly your surface heals
- Pool water versus sea or open water
- What your own surgeon instructs at the follow-up visit
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Who should not have PRK? Answer
Surface treatment is unsuitable where the cornea is unstable or too thin for the planned correction, where there is active surface disease or significant dry eye, and where the healing response is expected to be unpredictable. It is also a poor fit for someone who cannot follow a strict early aftercare routine.
What this depends on
- Corneal thickness and topography
- The state of the ocular surface
- Your ability to attend follow-up visits in the first days
Sources StatPearls, NCBI Bookshelf , Peer-reviewed literature (via PubMed Central)
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Can PRK be done after LASIK? Answer
Surface treatment is one of the ways a residual prescription after LASIK is corrected, because it does not require lifting the original flap. The decision depends on how much tissue remains and on the reason the residual is there.
This is one of the practical differences between the procedures that is easy to miss when choosing: after a flap procedure, enhancement can often be done by lifting the existing flap, and after a surface or lenticule procedure the options are different.
What this depends on
- How much corneal tissue has already been removed
- The size of the residual prescription
- Whether the residual has stabilised
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
Can PRK treat a high prescription? Answer
It can, within the limits the cornea allows, and surface treatment is sometimes chosen precisely because it conserves tissue compared with creating a flap. Higher prescriptions remove more tissue wherever the treatment is applied, so the measurement matters more than the technique.
What this depends on
- Corneal thickness and the depth the treatment requires
- Whether a lens-based option would be safer
- The haze risk associated with deeper surface treatment
Sources StatPearls, NCBI Bookshelf
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
What is surface ablation? Answer
Surface ablation is the family name for treatments that reshape the cornea from the outside rather than by lifting a flap or removing a lenticule from inside. PRK, LASEK, epi-LASIK and TransPRK are all surface ablation.
Grouping them is useful when reading a comparison: the trade-off a reader is choosing between is really surface versus flap versus lenticule, and the marketing names within each group describe technique details rather than different optical outcomes.
What this depends on
- Which category of treatment suits your cornea
- The recovery profile you can accommodate
- What your surgeon performs most often
Sources Peer-reviewed literature (via PubMed Central)
This information is for educational purposes and does not replace an examination by a qualified eye-care professional.
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These answers describe what is generally true. They are not a diagnosis and they cannot say whether a treatment is suitable for you, because suitability depends on measurements taken during an examination. Only a qualified ophthalmologist who has examined you can decide.
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.
- Laser In Situ Keratomileusis (LASIK)
The equivalent clinical reference chapter for LASIK, used so that comparisons describe both procedures symmetrically.
Used for How LASIK creates and manages a corneal flap; LASIK complication categories.
Link checked 22 September 2026
- Comparison of clinical outcomes of LASIK, Trans-PRK, and SMILE
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
- Refractive surgery and dry eye: an update
An update on how different refractive procedures affect the ocular surface, with attention to preoperative screening for dry eye.
Used for Why tear film assessment belongs in preoperative screening.
Link checked 22 September 2026
- Small Incision Lenticule Extraction (SMILE)
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
- ZEISS VISUMAX 800
The manufacturer’s own product page for the femtosecond laser platform used for SMILE pro.
Used for What describes the technology behind SMILE pro; The distinction between SMILE and SMILE pro; Claimed workflow features such as automated centration.
Link checked 22 September 2026
- Comparison of clinical outcomes following small incision lenticule extraction with the VISUMAX 800 and VISUMAX 500
A single comparative study of SMILE performed on the newer and older generations of the ZEISS platform. A single study, not a pooled analysis.
Used for The SMILE vs SMILE pro section, explicitly labelled as single-study evidence.
Link checked 22 September 2026
- DHA circular on the scope of practice for ophthalmologists performing laser refractive surgery
A Dubai Health Authority circular addressing how laser refractive surgery sits within the licensed scope of practice for ophthalmologists in Dubai.
Used for Explaining that refractive surgery is a regulated activity in Dubai.
Link checked 22 September 2026
- SMILE Laser Eye Surgery: What to Expect
Hospital patient education describing what happens before, during and after small incision lenticule extraction. It describes the typical course of treatment rather than predicting any individual outcome.
Used for What SMILE involves, for readers arriving before the procedure pages; What the period immediately after treatment is typically like.
Link checked 23 September 2026
- PubMed: biomedical literature search
The index we point readers to when they want to read the primary literature themselves rather than take our summary of it.
Used for Encouraging readers to check primary sources.
Link checked 22 September 2026