LASIK

01 · Overview

Overview

Reshaping the cornea

The cornea is the transparent, curved surface at the front of the eye. It provides most of the eye's focusing power. When its curvature does not match the length of the eye, the image forms in front of or behind the retina: this is myopia, hyperopia or astigmatism.

LASIK permanently changes the curvature of the cornea with a laser so that the image forms in the correct place. The procedure takes place in two stages: a thin flap is cut on the surface of the cornea and lifted; the laser sculpts the tissue underneath; and the flap is repositioned — it adheres naturally, without stitches.

The procedure takes a few minutes per eye, under anaesthesia with eye drops and without hospitalisation.

What the laser does not do, and never will

It does not prevent presbyopia. At around forty-five, near vision becomes difficult for everyone: the crystalline lens loses its flexibility, and the laser does not act on it. Reading glasses will be required, even after successful LASIK.

It does not remove the risks associated with myopia. In a person with high myopia, the risk of retinal detachment, macular disease or glaucoma remains the same after surgery: the eye remains myopic; only its surface has been changed. Lifelong examination of the back of the eye remains necessary.

It does not remove the need for ophthalmological follow-up or monitoring for cataracts with age.

02 · Indications

Indications

Who might this technique be suitable for?

• myopia, hyperopia or astigmatism within the limits permitted by corneal thickness;
• a correction that has been stable for at least one year;
• adulthood;
• a cornea with sufficient thickness and normal topography;
• no significant dry eye;
• no eye disease contraindicating the procedure;
• realistic expectations, particularly regarding future presbyopia.

The examination on which safety depends

Corneal topography — precise mapping of the cornea's shape and thickness — is the central examination in the assessment. It is used to detect keratoconus, a disease that progressively weakens and deforms the cornea, sometimes at a stage that is not yet clinically visible.

Performing LASIK on a predisposed cornea can trigger progressive, irreversible deformation that may seriously compromise vision. This is the most feared complication of this surgery, and it is largely avoidable with a rigorous assessment.

A centre that operates without complete topography, or accepts a case with questionable topography, creates a disproportionate risk. This is the most important criterion for judging how serious a proposal is, well before price.

03 · Techniques

Techniques

Three approaches, depending on the cornea

LASIK

A corneal flap is created, followed by deeper laser treatment. Visual recovery is very fast and postoperative comfort is high. The flap remains an area of reduced resistance permanently, requiring lasting caution regarding eye trauma.

Surface treatment

The laser acts directly on the surface without a flap, after removal of the superficial layer, which then regenerates. No flap is created, which is an advantage when the cornea is thin or an activity exposes the eye to impacts. In return, the first few days are considerably more painful and visual recovery is slower, over several weeks.

Small-incision lenticule extraction

The laser shapes a lenticule of tissue inside the cornea, which is removed through a small incision, without a complete flap. This is an intermediate technique with more limited indications.

None of these techniques is absolutely superior: the choice depends on the correction, the thickness and shape of the cornea, dry eye and lifestyle.

04 · Preparation

Preparation

Before the procedure

The assessment includes measurement of the correction with and without pupil dilation, corneal topography, measurement of corneal thickness, examination of the ocular surface and assessment of dryness, measurement of intraocular pressure, and examination of the back of the eye — particularly careful in people with high myopia, looking for peripheral retinal lesions that must be treated beforehand.

Contact lenses must be removed for several days to several weeks before the assessment, depending on their type: they distort the cornea and would make the measurements inaccurate. This interval is not negotiable, because an inaccurate measurement would lead to inappropriate treatment.

05 · Aftercare

Aftercare

After the procedure

First few hours

Watering, a burning or gritty sensation, and sensitivity to light. Resting with the eyes closed is recommended.

Vision

After LASIK, improvement often begins the next day, with a period of fluctuation.

After surface treatment, recovery is slower, over several weeks.

Eye drops

Local treatment and artificial tears are prescribed and must be used rigorously for several weeks.

Do not rub

An essential instruction after LASIK: rubbing the eye can displace the flap. A protective shield is worn at night as instructed.

Dryness

Very common for several weeks to several months, with fluctuating vision and discomfort.

Precautions

Swimming pools, hammams, make-up, contact sports and dust must be avoided for the specified periods. Protect the eyes from sunlight.

Signs requiring urgent medical attention

Severe and increasing pain, reduced vision, significant redness or discharge. An infection or flap complication must be treated without delay. After a blow to the eye, even long after the procedure, a consultation is necessary.

06 · Outcomes

Outcomes

What can reasonably be expected

Outcomes are usually very satisfactory for moderate corrections, with independence from glasses achieved in a large majority of cases for distance vision.

Some qualifications:

• some residual refractive error is possible, and an enhancement may be offered later if the cornea permits;
• partial regression may occur over the years, especially with high corrections;
• night vision may remain different — halos and glare around headlights — particularly in people with large pupils;
• presbyopia will develop normally with age.

07 · Risks

Risks

Risks and complications

• Dry eye — the most common complication, usually temporary but sometimes lasting and disabling;
• Halos, glare and difficulty with night vision;
• Undercorrection or overcorrection, requiring an enhancement or residual spectacle correction;
• Regression over time;
• Flap complications: folds, displacement, growth of cells beneath the flap, or inflammation at the interface;
• Corneal infection, rare but serious;
• Corneal ectasia — progressive, irreversible deformation of the cornea, the most serious complication, which may lead to a transplant. It occurs mainly in predisposed corneas that were not detected;
• Loss of visual quality that cannot be corrected with glasses, which is exceptional;
• Lasting sensitivity of the eye to trauma after LASIK because of the flap.

08 · Contraindications

Contraindications

Situations requiring particular assessment

• confirmed keratoconus or suspicion on topography — a major contraindication;
• a cornea that is too thin for the proposed correction;
• an unstable correction;
• significant dry eye;
• glaucoma or untreated retinal disease;
• eye infection or inflammation, or ocular herpes;
• an autoimmune or systemic disease;
• poorly controlled diabetes;
• pregnancy or breastfeeding — the procedure is usually postponed because the correction may vary;
• treatment that alters healing;
• an activity with high exposure to eye impacts — this favours surface treatment;
• unrealistic expectations, particularly regarding presbyopia or night vision.

09 · Frequently asked questions

Frequently asked questions

Questions patients often ask