What the medical literature says
Common side effects
Dry eye
This is the most common side effect after Femto-LASIK. Creating the flap severs superficial corneal nerves, temporarily reducing corneal sensitivity and reflex tear production. Postoperative dry eye affects 20 to 55% of patients depending on the studies, but in the vast majority of cases is transient and resolves in three to six months with appropriate treatment.[1]
PRK, which treats the surface, affects corneal innervation less. It is preferred in case of pre-existing dryness.
Night halos and glare
Almost universal in the first postoperative weeks, they correspond to light diffraction at the transition zone between treated and untreated cornea. They diminish progressively as the cornea heals and the brain adapts. At three months, they are residual or absent for the majority of patients.[2]
Their persistence beyond six months is possible, particularly for larger corrections or wide pupils in scotopic conditions.
Transient visual fluctuations
In the first weeks, vision can vary with the time of day, fatigue or hydration. It is a normal phase of corneal healing. It generally stabilises in one to three months for Femto-LASIK, in three to six months for PRK.
Regression
A slight loss of the correction achieved can occur in the months or years following surgery, particularly for high myopia. It is generally minimal and can be treated with a laser enhancement if needed.[3]
Serious risks: rare but real
Corneal ectasia
This is the most feared complication. It corresponds to a progressive thinning and deformation of the cornea after laser ablation, similar to keratoconus. It occurs mainly in patients with pre-existing corneal fragility undetected during the exam, or insufficient residual thickness.[4]
Its frequency is estimated at 0.04 to 0.6% of cases depending on the populations studied. It is largely predictable and avoidable with a rigorous topographic exam. This is the main reason why corneal topography is the most important test of the preoperative exam.
Flap complications (Femto-LASIK)
Flap folds, traumatic displacement, irregular interface. These complications are rare since the introduction of the femtosecond laser (less than 1% in total) and in the majority of cases treatable.[5]
Infection (infectious keratitis)
Exceptional thanks to systematic antibiotic protocols. Its frequency is estimated at less than 0.02% of cases in centres respecting sterilisation and postoperative prescription standards.
Corneal haze (PRK)
A slight superficial opacification of the cornea can occur after PRK, especially for larger corrections. The application of mitomycin C at the end of the procedure has significantly reduced this risk. It remains possible in cases of overcorrection or atypical healing.[6]
