Principles of the eye laser operations
Myopia, astigmatism, hyperopia and presbyopia, they are corrected by lenses or eyeglasses, can now be the subject of a long-lasting correction by laser. The laser eye operations to correct Visual defects such as myopia (refractive surgery) are, with the cataract surgery, surgical techniques the most practiced in the industrialized world, and this across all surgical specialties. Better vision without glasses is now within the reach of many patients, but it is important to surround yourself with the best conditions, in particular a preoperative assessment of quality, and ensure that the material used (laser) is in line with the latest technological advances.
Correction of ametropia by refractive surgery
Excimer laser operations constitute the vast majority of refractive surgery. Excimer laser refractive surgery allows to correct an optical flaw by playing on the optical power of the cornea: this laser can sculpt the corneal profile in order to increase or reduce the optical power. The main variants of laser interventions have similarities and differences.
All laser procedures are performed under local anesthesia, by single instillation of eyedrops. A light tranquilizer is possible. Both eyes are made the same day in the vast majority of the case, in a painless way. Recovery is early and the postoperative are simple, lasting only a few days for the slower techniques.
The main variants of laser operations are
-the LASIKwhere the corneal reshaping is performed in depth, after a superficial flap femtosecond laser cutting.
-the PKRwhere the corneal reshaping is made on the surface, after simple removal of superficial corneal epithelium.
-the Smile is a technique of using femtosecond laser for cutting "block" a lenticule of corneal tissue in the depth of the cornea and then remove it manually through an incision.
Operations by implant
When myopia or hyperopia are very important and cannot be the subject of a correction laser on the cornea, some constituent to add techniques a intraocular implant may be considered.
Similarly, when there is a cataract, the cataract surgerywhich includes the extraction of the clouded lens and its replacement with an implant of power and features, allows the patient to do without glasses after surgery, either from a distance or close)monofocal implant) is by far and near)Multifocal implants). Them implants-rings allow to correct the corneal astigmatism (they can be o-rings o-rings or monofocal multifocal according to the desired optical correction).
The calculation of the power of the implant is performed before the operation (biometrics): it assumes certain measures such as keratometry (corneal optical power measure), the measure of the axial length of the eye, and the use of a calculation formula power implant adapted.
* The refractive visual defects or "possible" are related to :
-excessive refractive power of the eye (myopia): the plan of the sharp image is in front of the retina
-a failure of refractive power of the eye (hyperopia): the plan of the sharp image is behind the retina
-a variation of the refractive power of the eye based on the meridians (astigmatism)
-a lack of accommodation to see net objects close together (presbyopia).
Refractive surgery has for principles of correct the eye by reducing its excess of optical power (myopia) or, on the contrary, by increasing its optical power (hyperopia). Astigmatism correction is based on the regularization of the optical power of the different meridians. Compensation of presbyopia is intended to allow the eye to see net infinity (far) at a close distance (reading).
Action Sites affected by refractive surgery
The main sites of action of refractive surgery are:
-the cornea (excimer laser surgery- LASIK or PKR(, relaxing incisions, Smile). The use of the laser to change the optical power of the cornea changing its shape (remodeling by sculpture laser). On this site you will find a detailed information on the characteristics of ablation profiles for the correction of these optical defects by the excimer laser.
-the lens of the eye (cataract surgery)
-more rarely the rooms before and after the eye (by insertion of an implant surgery called "implant phakic", without removal of the lens).
The replacement of the lens with a suitable power implant allows to correct a defect optical pre existing as myopia, hyperopia, or astigmatism (implants-rings). The replacement of the lens is indicated when it loses its transparency (cataract), or for very strong ametropia correction. The cataract surgery has a refractive dimension, and can also be coupled with the laser surgery to perfect a refractive outcome.