PRK – Photorefractive Keratectomy – Laser Surgery
Photorefractive keratectomy (PRK) is a simple and effective refractive surgery technique requiring only a single laser. Developed before LASIK to correct myopia, astigmatism, and mild hyperopia, and later superseded, its use has seen a resurgence with improvements in technology. The laser used is called an excimer laser; it reshapes the cornea to correct its refractive power and the refractive error of your eye. The procedure is performed under local anesthesia with eye drops, lasts approximately 15 seconds per eye, and doesn't even require touching the eye in the case of the transepithelial PRK (t-PRK) technique. A bandage contact lens is then placed on your eye to facilitate healing and minimize pain. It is removed 3 to 4 days after the procedure. Visual recovery is slower than with LASIK, but the risk of complications is lower.
Photorefractive keratectomy – PRK and t-PRK
With PRK, your ophthalmologist uses a laser to reshape the surface of your cornea.
This improves how light rays are focused onto the retina.
PRK is used to treat myopia, astigmatism, and to a lesser extent hyperopia and presbyopia.
The goal of photorefractive keratectomy is to correct your refractive error to improve your vision without glasses.
PRK can eliminate or reduce your need for glasses and contact lenses.
Why choose a PKR?
If you have mild myopia, dry eyes, or a thin cornea and are considering refractive surgery, PRK may be a good option for you. LASIK and SMILE are more likely to cause dryness and are more limited in their suitability for thin corneas.
Similarly, if you participate in combat sports, have a very active lifestyle, or a very active job, PRK may be a better technique for you than LASIK. This is because PRK does not involve cutting a flap in your cornea as LASIK does. If you are very active, you could accidentally dislodge or tear this corneal flap. This is a serious complication of LASIK.
Eligibility
To perform a PRK procedure, you must meet certain conditions:
Be 18 years of age or ideally over 20, when vision is more likely to have stopped changing.
Having a stable refractive error – Your corrections must not have changed by more than 0.50 diopters for 3 years before age 25 or 2 years after age 25.
Your refractive error must be within the limits of those that can be treated by PRK (-8 for myopia, -6 for astigmatism, +6 for hyperopia).
Your corneas must be healthy and of sufficient thickness.
You must not suffer from certain general diseases such as rheumatoid arthritis or lupus.
Your expectations must be in line with the desired final results.
You must understand the post-operative procedures and agree to comply with the planned treatments and check-ups.
Contraindications and ineligibility
For some patients, PRK is contraindicated. This includes, in particular, people with:
An unstable (changing) refractive error – particularly progressive myopia.
A skin disease or any other disease that may affect wound healing.
Uncontrolled diabetes – Note well, well-controlled diabetes is not a contraindication.
Keratoconus or any other progressive corneal disease
Advanced or unstable glaucoma.
A cataract.
Being pregnant or breastfeeding
An active eye infection or a significant scar
Your ophthalmologist will discuss with you the indications and contraindications for surgery after a thorough examination.
Pre-operative assessment and examinations
To determine if you are a candidate for PRK, your ophthalmologist will examine your eyes. Here's what will be done:
Refraction – Measurements will be taken of your eyes and glasses.
Clinical examination – Dry eye, cataracts or fundus abnormalities will be sought.
Topography – Measurements with 3D reconstruction of your cornea will be taken.
Pachymetry – The thickness of your cornea will be measured to ensure that it is sufficient.
Pupillometry – The size of your pupil will be checked in order to control the width of the laser treatment.
Cycloplegia – Refraction will be controlled with drops that relax accommodation (Skiacol) to ensure perfect correction.
Procedure for photorefractive keratectomy
Before the operation
The goal of any refractive surgery is to meet your visual needs and expectations. The pre-operative consultation will ensure that your needs and expectations are well aligned with the surgical technique.
At the end of the consultation, the secretary will give you a consent form, a quote and an operating date.
Here are some recommendations:
Contact your health insurance provider and assess their potential contribution to the reimbursement. Social security does not cover any costs.
Take 3 to 5 days off work after the operation; no sick leave will be issued as this is considered a "functional" surgery.
Arrange for someone to accompany you after the operation and make arrangements to return home by taxi or car.
Do not wear your contact lenses the week before the procedure.
Purchase the post-operative treatments a few days before the procedure so that you can start them as soon as you return home.
The day before the operation, remove your makeup carefully.
On the day of the procedure, wash your face with soap and water. Do not wear makeup, not even foundation on your cheeks!
Do not tie your hair up or make a low ponytail.
During photorefractive keratectomy (PRK) – Procedure
PRK is usually performed at the laser institute, where several ophthalmologists pool their investments in the latest platforms.
Final checks can be carried out before the operation.
The procedure lasts approximately 10-15 minutes. Here's what you should expect:
Your eye will be anesthetized with drops, the operation will be painless.
The operation takes place while lying on your back.
Your ophthalmologist will place an eyelid support (blepharostat) on your eye to prevent you from blinking.
Next, it removes the outermost layer of cells from your cornea, called the epithelium. To do this, it may use:
The laser – This is trans-PRK, the latest non-contact evolution of PKR.
An alcohol solution and a brush – This is the manual PKR technique.
You will then need to focus on a bright target so that your eyes do not move. The laser will remain fixed on it and will automatically stop if you move your eyes unintentionally.
Using a laser, the surgeon reshapes your cornea. The procedure will have been pre-programmed with corrective measurements tailored to your eye.
The laser treatment lasts approximately 15 seconds. During the laser treatment, you will hear a clicking sound and may perceive a smell of "burnt hair".
At the end of the procedure, the eye is rinsed with sterile water, a healing modulator (mitomycin) is applied for a few seconds, and a contact lens is placed on your eye. This will have a soothing and healing effect.
Post-operative and recovery after PRK
The first three days are the hardest with PRK. Here's what to expect and some advice:
Arrange for someone to accompany you home. Once you get back, rest and feel free to take a nap.
Do not return to work immediately, but 4 to 5 days after the procedure.
Avoid sports for the first 5 days as well.
For two or three days after PRK, you may experience some eye pain. Patients often compare this pain to having a finger in their eye.
Start treatment a few hours after the operation.
Pre-prescribed painkillers will help you manage the discomfort. Feel free to place a clean, cold compress on your eyelids for relief.
Wear sunglasses as you will be photophobic (sensitive to light).
Your vision will be very blurry for the first 3 days. It will improve significantly after 1 week and will be perfect after 1 month.
The bandage lens will be removed 3 to 4 days after the operation, at the time of the 1st postoperative check-up.
What are the advantages of PKR?
PRK involves applying the laser directly to the eye. While this technique requires a longer recovery time, it nevertheless offers numerous advantages:
Dryness is very rare because no cutting of the corneal nerves is performed.
Ectasias are exceptional – The technique alters the collagen structure of the cornea less.
Thin cornea – This technique is more suitable than Lasik for thin corneas.
No contact – The transPRK technique allows the surgeon to avoid touching your eyes during the procedure. If you are concerned about the suction involved in LASIK, PRK is the preferred option.
Rapid procedure – This is the fastest technique, the operative experience is often better than with lasik or smile.
What are the risks and complications of PRK surgery?
Like any surgical procedure, PRK carries risks of dissatisfaction and even complications that you should be aware of. These risks are:
Photophobia and photopsia – Glare and halos around lights, especially at night.
Recurrent ulcer – Difficult corneal healing
Haze – Scarring opacity of the cornea.
Abscess – Corneal infection.
Ectasia – Corneal herniation due to excessive thinning. This complication is much less frequent than after LASIK.
Over- or under-correction – Residual myopia, hyperopia, or astigmatism remains. This can be corrected with glasses, contact lenses, or laser surgery.
Irreversible visual sequelae are exceptional in refractive surgery.
What will my vision be like after a PRK?
More than 90% of patients who underwent surgery have visual acuity between 12/10 and 16/10 in each eye, without correction, after the operation.
It's important to know that PRK cannot correct presbyopia. This is the normal age-related loss of near vision flexibility. With or without refractive surgery, almost everyone with excellent distance vision will need reading glasses after the age of 40.
To combat presbyopia, some people opt for PRK to achieve monovision. This means that one eye is left slightly nearsighted (for near vision) and the other eye is emmetropic (for distance vision). The brain learns to adapt so that the nearsighted eye is used for close work, while the other eye sees distant objects. Monovision is not suitable for all patients and must be tested with contact lenses before the operation.
Frequently Asked Questions
What is the difference between a PKR and a t-PKR (trans-PKR)?
PRK and trans-PRK are two almost identical procedures.
In the case of classic PRK, the epithelium is removed manually (scraped).
In the case of trans-PRK, the epithelium is removed with a laser (non-contact procedure)
What is the visual recovery like after a PRK procedure?
Visual recovery after PRK follows the following timeline:
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Blurred vision + discomfort or pain for 3 days.
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6/10 after 3 to 4 days.
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8 to 10/10 after 1 week.
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10 to 12/10 after 1 month.