WHAT IS IT AND HOW IS IT TREATED
REFRACTIVE EYE SURGERY refers to all techniques for correcting refractive faults by intervening on the cornea or lens.
These faults are primarily myopia, hypermetropia, astigmatism, and also include presbyopia. All refractive faults can be corrected using various types of procedure: the primary classification is between corneal and intraocular surgery.
The defects mentioned can normally be corrected wearing glasses and contact lenses. Surgery is generally advised or can be a solution when those sight aids cannot easily be used, as in cases of intolerance to lenses, work activities where use of contact lenses is problematic, or simply through the wish to become free from such aids during daily life.
The defect’s value must be measured by an ophthalmologist, who must acquire a series of data before any surgery. The most important data are measuring the sight defect, corneal topography (the curvature of the eye surface), pachymetry (corneal thickness measurement) and pupil diameter.
The most widespread refractive laser surgery techniques include:
PRK (Photo Reactive Keratectomy, or refractive photo keratectomy) is effective on myopia, astigmatism and hypermetropia. This technique uses excimer lasers, which remove the tissue by precisely evaporating tissue at a scale of thousands of a millimetre (microns).
The doctor first removes the surface of the cornea, the epithelium, manually, and then performs laser ablation.
In the end a protective contact lens is applied which will be removed at subsequent stages, when the epithelium will be reshaped or when the doctor deems it most appropriate.
LASEK (Laser Epithelial Keratomileusis) is a treatment similar to PRK, which involves lifting the original epithelium rather than removing it.
The epithelium is preserved in an alcohol solution, which also weakens its adhesion, lifted but not completely removed, and folded at the side (epithelial flap). Then the excimer laser is applied as in PRK, and the epithelium is replaced to its original position, where it re-joins naturally.
The protective contact lens is applied over the epithelium, which remains mostly intact. It is very important not to knock or rub the eye for a few days.
Epi-LASIK Variant of LASEK. The epithelium is not removed from the underlying layer with an alcohol solution, but mechanically using a separate instrument called an epikeratome. This technique allows the epithelium partly to retain its vitality.
SMILE (Small Incision Lenticule Extraction) is a technique for correcting sight defects such as myopia and myopic astigmatism. It uses femtosecond lasers to implant a refractive lens which is removed via a very small corneal incision, all in one procedure.
This procedure can be carried out without making a corneal flap, as in LASIK, or superficial ablation as in PRK.
Refractive defects can also be corrected after removing the cataract and then implanting the intraocular lens (IOL). Thanks to constant technological progress it is now possible to use intraocular lenses (IOL), that differ in terms of shape, material and size, and with different optical power, to allow maximum adaptability for correcting a greater variety of sight defects and eye structures.The choice of the most suitable IOL to implant is important for the success dof the cataract procedure.. Therefore the specialist, following a thorough consultation and preoperative exam, will decide whether the patient is a good candidate for the intervention and the best IOL for an optimal result. In cases with the appropriate optical conditions, this can even lead to not needing to use glasses.