The cornea is one of the lenses that forms part of the eye. As every lens, it requires an appropriate shape and transparency. If any of these variables is affected, vision can be lost. If it cannot be improved with eyeglasses, surgeries performed by an experienced surgeon are required. In order to do this, a thorough evaluation of the patient is essential, among with supporting tests that are necessary to make a perfect choice in each case.
LASIK, PRK, ICL Y FACOREFRACTIVA.
The LASIK technique is a refractive surgery that uses cutting-edge technology. It lasts a few seconds and it is an outpatient surgery that is performed under topical anesthesia. It improves the vision quality of myopia, astigmatism and hyperopia patients.
The procedure involves creating a corneal flap and reshaping the cornea using a laser according to the necessities of each patient, eliminating optical aberrations.
In order to perform this kind of surgery, certain requisites must be met and evaluated by the surgeon. The cornea must have a certain thickness, it must also be regular and have an appropriate curvature. In order to evaluate all those variables, there are supplementary tests such as the Pachymetry, the Topography and the Pentacam If these requirements are not met, other techniques should be taken into account, such as PRK.
PRK (excimer laser) involves a technique in which a superficial epithelial debridement is performed and a laser is used on the cornea, without having to create a flap. Then, a therapeutic contact lens is applied, and removed later. The after surgery care is longer and the visual recovery is slower than with LASIK.
Another alternative surgery is the application of ICL (implantable collamer lens) contact lenses, in which an intraocular lense is applied preserving the crystalline in order to correct refractive errors. This technique is perfect for patients who suffer from severe myopia or hyperopia. It is an outpatient surgery, and it is performed under topical anesthesia.
If patients are over the age of 40, or if they suffer from farsightedness, FACORREFRACTIVA surgery can be considered. It involves the removal of the crystalline and its replacement for an intraocular lens that is adapted to the patient’s needs.
A corneal transplant is necessary when there is corneal opacity as a result of a trauma, an infection or diseases that may affect corneal transparency. It is also necessary in advanced ectasias and keratoconus or in the ones in which other less invasive methods were not successful.
It involves the transplant of the overall thickness of the cornea. A donated cornea is used for each particular case.
The procedure is carried out in the OR, under local anesthesia. The donated tissue is sewed and the stitches are removed 2 or 3 months after the surgery. The recovery is slow and requires thorough checks in order to evaluate progress and any signs of rejection of the tissue.
The cornea is a tissue made of several layers distributed in a regular form. In this procedure, only the affected layer is removed and replaced by a donated tissue, leaving the healthy layers. Endothelial transplants (DSAEK/DMEK) are performed when the cells which are in charge of keeping the cornea transparent do not work properly.
The difference between DSAEK and DMEK is that in the former, more layers are included (the endothelium, the descemet’s membrane, and part of the corneal stroma.) The DMEK only includes the endothelium and the descemet’s membrane, that is to say, less layers are transplanted. One of the most common indications is the endothelial dystrophy.
There is a procedure in which a deep lamellar corneal transplant is performed with the “Big Bubble” (DALK) technique. Common indications include diseases in which the anterior part of the cornea is altered, but the endothelium is normal, as in the keratoconus, or in dystrophies. In this case, part of the cornea layers are detached by an air bubble and the donor button is transplanted.
The benefits of lamellar transplants, as opposed to the complete corneal transplant are several. The most important ones are: they reduce the visual recovery time, the posterior astigmatism and the risk of corneal rejection.
The keratoconus is a disease in which the shape of the cornea is affected, and starts taking on the shape of a cone. This leads to corneal deformation and consequently, to vision alteration.
The implantation of intracorneal rings is carried out in the OR, under local anesthesia. The aim of the surgery is to modify the corneal curvature flattening it through the tension that the rings generate. In this way, the deformation produced by the corneal ectasia is reduced.
It is a method in which new molecular bonds are created in order to strengthen the corneal collagen weakened by diseases such as keratoconus.
This treatment should be carried out in the OR, with extreme care of the antisepsis. The patient is given topical anesthetics 10 minutes before de-epithelization. Every 3 minutes the patient is given riboflavin 0,1% during 30 minutes. Then comes irradiation for 30 minutes. Afterwards, a contact lens is applied. In the after surgery, antibiotics and corticoid eye drops are administered. Nonsteroidal anti-inflammatory drugs can additionally be prescribed until the ulcer heals. Once re epithelialized, the contact lens is removed and the corticoid eye drops should be continued up to between 4 weeks and 3 months.
Crosslinking is indicated in patients that suffer from keratoconus, progressive corneal ectasias, in young patients (up to the age of 40 approximately) and in patients with corneal thickness up to 400 microns.