Prof. Michael Mimouni worked extensively with advanced laser vision correction technologies during his fellowship in Toronto, Canada. In recent years he has published dozens of scientific papers focused on improving the outcomes of refractive surgery procedures.
What does “laser vision correction” involve?
This is a fascinating field that offers multiple options, each of which must be tailored to the individual patient. The field is divided into two categories: (a) corneal-based treatments, which reshape the cornea so that it focuses light rays in a way that reduces (or eliminates) the need for glasses or contact lenses; and (b) intraocular treatments, which are based on adding a lens or replacing the natural lens in order to focus light rays and reduce dependence on glasses.
This page deals mainly with the first category — the treatments that reshape the cornea using a laser, chiefly LASIK and PRK.
Is everyone a candidate for these procedures?
The answer is no. The first step is a conversation with the patient to understand their needs and expectations. Next, a thorough examination and evaluation using advanced diagnostic instruments is required to confirm that the eye is suitable for the treatment in question. Only then can we discuss the available treatment options, their success rates, and align expectations.
It is important to distinguish between “not suitable” and “not suitable right now”. A prescription that is still changing from year to year, pregnancy and breastfeeding, significant untreated dryness, or active inflammation of the ocular surface are all reasons to wait, treat what can be treated, and re-examine later — not necessarily a permanent disqualification.
What the preliminary examination checks
The central examination before laser surgery is corneal mapping — a scan that measures the shape and the thickness of the cornea at every point. One of its purposes is to identify a cornea that is too thin, or a suspicious shape that may indicate keratoconus, a condition in which LASIK is unsuitable and may cause harm. Alongside the mapping we measure the exact prescription, the pupil diameter, the intraocular pressure, and the state of the ocular surface and tear film — because an eye that is dry before surgery tends to be drier after it.
Types of laser vision correction
There are several types of laser-based procedures. All of them rely on the same principle: reshaping the cornea so that it focuses light rays exactly where they are needed. The two most common procedures are (a) LASIK, which stands for laser-assisted in situ keratomileusis, and (b) PRK, which stands for photorefractive keratectomy. In LASIK, a thin flap is created using a laser or a microkeratome, a second type of laser is then applied to reshape the cornea according to the patient’s needs, and finally the flap is repositioned. In PRK, the outer epithelial layer of the cornea is removed, the laser is then applied to reshape the cornea, and the epithelium is allowed to regenerate, usually within a few days.
In recent years a further method has been added, in which the laser creates a thin lenticule within the thickness of the cornea and it is extracted through a small incision, without creating a full flap. The techniques continue to evolve, but the principle remains the same: a precise change to the curvature of the cornea.
What are the advantages of LASIK?
Because the corneal epithelium is not removed in LASIK, visual recovery is faster and there is almost no pain after surgery (compared with PRK). Most patients are able to return to normal activities within a few days. For this reason, LASIK is the first-line treatment offered to suitable candidates.
What are the advantages of PRK?
In PRK, no corneal flap is created. Therefore, patients who are not candidates for LASIK (typically those with a cornea that is not thick enough or is slightly irregular) can be evaluated for PRK. Numerous studies have demonstrated that PRK today achieves results very similar to those of LASIK, but the recovery period is longer. Most patients experience discomfort or pain for several days (while the epithelial layer regenerates), so it is standard practice to place a bandage contact lens at the end of the procedure to relieve pain and accelerate epithelial healing. In terms of vision, most patients achieve functional vision within a week and their best vision within about a month.
LASIK or PRK — how the decision is made
The decision is almost always settled by the cornea rather than by preference. A thick, regular, healthy cornea allows both options, and in that case LASIK wins on the strength of its faster and more comfortable recovery. A relatively thin cornea, a borderline shape, or an eye at increased risk of direct trauma — contact sports, operational occupations — tips the balance towards PRK, which leaves no flap in the cornea. In borderline cases it is worth weighing the recovery gap: a few days versus a few weeks.
What recovery looks like
On the day of surgery vision is blurred and hazy, and the eye is sensitive to light. After LASIK vision usually clears during the first day or two. After PRK the first days are the hardest, until the epithelium closes, after which vision improves gradually over weeks.
In both cases antibiotic and steroid drops are started according to instructions, along with lubricating drops that usually continue for several months. You should avoid rubbing the eyes, eye make-up, swimming pools and open water, and dust and dirt during the first weeks, and protect the eyes in the sun. A sensation of dryness, glare around lights at night, and fluctuations in vision during the day are an expected part of the recovery period and fade with time — I have written about this at length on the page about dry eye after laser surgery.
The PRK recovery calculators
Based on research covering more than 180,000 laser surgeries, these tools give you a personalised estimate of your recovery path: the PRK recovery calculators, which include the return-to-driving calculator and the visual recovery calculator.
Are complications possible?
The answer is unequivocally yes, but the risk is low. Prof. Mimouni studied the outcomes of 70,000 surgeries performed over 20 years in order to determine the likelihood of any complication and how complications can be prevented. Among other findings, these studies showed that the risk of complications has steadily declined in recent years thanks to improvements in technique, technology, and knowledge. It is worth noting that several mathematical models have shown that the risk of a complication from long-term contact lens wear is higher than the risk of any complication from laser vision correction surgery.
The most common complication is not dramatic but bothersome: dry eye in the months following surgery. Less common are over-correction or under-correction requiring an additional procedure, glare and halos around lights, and flap-related problems after LASIK. Serious complications such as infection or ectasia (progressive weakening of the cornea) are rare, and a meticulous preliminary examination is the main tool for preventing them.
What are the chances of getting rid of glasses?
Prof. Mimouni investigated the likelihood of requiring an additional procedure down the road, based on data from 70,000 surgeries, and reported that this likelihood has decreased steadily over the years. Fifteen years ago the answer was 5%; today it ranges around 1–2%, depending on the patient’s eye. In most cases, even when glasses cannot be eliminated entirely, dependence on them can be significantly reduced.
Expectations should be aligned on one point in particular: the surgery corrects the prescription you have today, but it does not stop the eye from ageing. From around the age of 45 presbyopia develops — the difficulty of focusing at near — and even patients who have had a successful procedure may come to need reading glasses.
Examination and consultation with a specialist
Whether laser surgery is right for you is not answered by your prescription, but by what is seen on corneal mapping and on examination of the ocular surface. Prof. Michael Mimouni is a specialist in cornea and the ocular surface, and in his research he has analysed data from tens of thousands of laser procedures. The examination establishes which techniques are relevant for you, what the realistic prospects are in your particular eye, and what is worth doing before you decide.
On the financial side — what drives the price, what a quote should include, and what the supplementary insurance plans provide — I have written separately on the page about the cost of laser eye surgery. To arrange an examination or ask a question, please get in touch.
Frequently asked questions
How long does laser vision correction take?
The part in which the laser is actually working lasts seconds to tens of seconds per eye, and the whole stay in the treatment room is usually about a quarter of an hour for both eyes. Most of that time goes to positioning, disinfection and final checks rather than to the laser itself.
Is the procedure painful?
No. The treatment is performed under topical anaesthesia with drops and is not painful. The difference is felt afterwards: after LASIK there is almost no pain, whereas after PRK most patients experience discomfort or pain for several days while the epithelium regenerates. A bandage contact lens is placed at the end of the procedure to reduce the pain.
When can I return to work and to driving?
After LASIK most patients return to normal activities within a few days. After PRK most patients reach functional vision within about a week and their best vision within about a month. Returning to driving depends on the visual acuity measured at the follow-up examination, not on a date in the calendar.
Does the result last for life?
The change made to the cornea itself is permanent. The eye, however, continues to age: from around the age of 45 presbyopia develops and reading glasses may be needed, and at an older age a cataract may form. These are separate processes and not a failure of the surgery.
What if my cornea is too thin for LASIK?
A cornea that is too thin is not necessarily the end of the road. Some patients can be evaluated for PRK, which does not require creating a flap, while for others the appropriate solution is an intraocular treatment in which a lens is added. The decision is made on the basis of corneal mapping, not on the basis of the prescription alone.
Do the health funds cover laser vision correction?
Laser vision correction is considered an elective procedure and is not included in the national health basket. The supplementary insurance plans of the health funds sometimes offer a contribution or a discount through agreements with particular centres, and the terms vary between funds and are updated from time to time. It is worth checking what currently applies with your own fund before you set a date.