Preparation
Contact lenses out at least three days beforehand. Anaesthetic eye drops, then a lid speculum is placed to hold the eyelids open. Plan not to work for the following days.
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Trans-PRK
Transepithelial photorefractive keratectomy, with no contact
Trans-PRK works at the surface. No flap is cut and no instrument touches the eye: the excimer laser itself removes the epithelium, then reshapes the cornea, in a single step. It is the reference technique for thin corneas and for eyes exposed to knocks, at the cost of a longer recovery.
No contactThe laser removes the epithelium
30 secondsOf photoablation per eye
5 to 7 daysTo functional vision
Thin corneasAnd high-risk jobs
The procedure
How the operation goes.
As a day case, under anaesthetic eye drops, in the laser suite at the Institut Voltaire (Paris 11th). Consultation, assessment and follow-up take place at the practice in Rueil-Malmaison.
Excimer laser
The Schwind Amaris 750s removes the epithelium, then reshapes the cornea in one step, with no contact. About thirty seconds per eye, while you look at a point of light. Depending on the correction, a product that limits scarring haze may be applied for a few seconds, then rinsed off.
Bandage contact lens
The eye is rinsed, then a bandage contact lens is fitted to protect the surface while the epithelium grows back.
Check-ups
A check-up on day five, once the epithelium has grown back, then at one month and at six months. The refraction settles over one to three months, sometimes longer depending on the correction.
The five steps of Trans-PRK: front view, then vertical cross-section of the cornea
Anaesthetic eye drops, then a lid speculum is placed. No instrument touches the cornea.
In a single sequence, the excimer laser removes the surface layer, then reshapes the stroma. No blade, no flap, no contact.
Depending on the correction, a product that limits scarring haze is applied for a few seconds, then the surface is rinsed.
A soft contact lens is fitted at the end of the operation. It protects the surface and eases the discomfort while the eye heals.
The surface layer grows back from the edge towards the centre over a few days, under the lens, before the lens is removed.
Treated area Epithelium Stroma Laser beam Instrument
Pros and cons
Its strengths, its limits.
No technique is better than the others in absolute terms. Each has situations where it is the best answer, and a downside you need to know about before choosing.
| Its strengths | Its limits |
|---|---|
| No deep cut: there is no flap, so no interface complications and no risk of the flap shifting. | A much longer recovery: the epithelium has to grow back, which takes three to five days on average, and everything else depends on it. Functional vision in five to seven days, quality of vision over two to six weeks. |
| Suitable for thin corneas: for the same correction, it uses up less corneal thickness than LASIK, and remains possible where a flap is ruled out. | Post-operative pain: marked discomfort is common in the first few days, unlike with LASIK and SMILE. |
| Less dry eye after surgery than with LASIK. | Fluctuating vision while the eye heals, which settles with time. |
| No contact with the eye: the laser itself removes the epithelium, which avoids handling with instruments and makes healing more even. | Time off work: you need to plan for it, whereas with LASIK you can go back to work the next day. |
| Suited to combat sports and high-risk jobs, where having no flap is the deciding factor. | · |
Trans-PRK fees
€2,600both eyes
€1,300per eye
All-inclusive fee: surgeon's fees, clinic and laser suite costs, consumables and post-operative follow-up. Not covered by French national health insurance (Assurance Maladie); many top-up health insurance policies (mutuelles) include a fixed allowance. Full fee information
Side effects and complications
What to expect, and what is rare.
The expected side effects come with the technique itself: they are common and temporary. Complications are rare. They are listed here because you have the right to know about them before you give your consent.
Expected side effects
- Pain and a gritty, foreign-body feeling: for the first three to five days, treated with painkillers and eye drops.
- Dry eye: temporary, but it may need a few months of treatment.
- Halos and glare at night: temporary, and milder than with LASIK.
- Delayed healing: blurred vision lasts longer.
Possible complications
- Haze: a clouding that reduces the transparency of the cornea. It is rare and made more likely by ultraviolet exposure, hence the strict instruction to protect your eyes from the sun.
- Under- or over-correction: requires an enhancement.
- Corneal ectasia: rare, but possible.
- Infection: rare, prevented with an antibiotic.
Who it suits
Indications.
These criteria are a guide, not a verdict: only the pre-operative assessment measures the actual geometry of your eyes.
Good candidates
- Thin corneas, where LASIK is contraindicated
- Combat sports, martial arts, rugby, diving
- Jobs with a risk of blows to the eye: police, firefighters, armed forces, construction
- Existing dry eye, where a flap would make things worse
- Preferably low to moderate corrections
What rules it out or means waiting
- Keratoconus, or a topography that suggests it
- Being unable to cope with five to seven days of blurred vision and discomfort
- Strong sun exposure that cannot be protected against in the following months
- High corrections, where a lens implant is preferable
- Pregnancy, breastfeeding, a refraction that is still changing
Enhancement
What if the result is not perfect?
Enhancement after Trans-PRK
An enhancement is done with a new surface photoablation, provided the cornea is thick enough. There is no flap to deal with, which makes the procedure simpler, but the recovery is once again that of a PRK.
Under-correction or regression can happen whatever the technique. If an enhancement is needed, it is included in the first year of follow-up.
Other techniques
LASIK
Quick recovery, straightforward enhancement.
SMILE
No flap, corneal biomechanics preserved.
ICL phakic lens
When the cornea is not suitable for laser.
SFO patient leaflet (in French)
Published by the French Society of Ophthalmology (Société Française d'Ophtalmologie, SFO), it describes the operation, its results and its risks. It forms the basis of informed consent, but does not replace the consultation.
Frequently asked questions
What I am asked most often.
Why choose Trans-PRK rather than LASIK?
Because your cornea is too thin for a flap, or because your sport or your job puts your eyes at risk of blows. In both cases, having no flap matters more than a comfortable recovery.
Is Trans-PRK painful?
The operation itself is painless. The three to five days after it, however, are uncomfortable: that is the main difference from LASIK and SMILE.
How much time off should I plan for?
Allow about a week. Your vision stays blurred while the epithelium grows back, and the bandage contact lens can usually be removed at the day-five check-up. High-quality vision takes two to six weeks to settle: that is the trade-off for having no flap.
What is haze?
A scarring haze that clouds the cornea. It is rare and made more likely by ultraviolet exposure, which is why protecting your eyes from the sun is essential for the following months.
What is the difference between PRK and Trans-PRK?
In conventional PRK, the epithelium is removed mechanically. In Trans-PRK, the laser does it, with no contact and in the same step as the correction.
Is Trans-PRK right for your eyes?
The questionnaire gives you a first indication in three minutes. The pre-operative assessment measures what cannot be guessed: corneal topography, corneal thickness, tear film and a dilated eye examination (fundus examination).
Dr Emmanuel Halimi
Ophthalmic surgeon · RPPS 10100555084 · Medical Council of Hauts-de-Seine no. 92/23003
Page written and approved by the surgeon.
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