What are myopia, hypermetropia and astigmatism?
Myopia, hypermetropia, astigmatism and presbyopia (eyestrain) are the commonly named refractive disorders. The capacity of the eye to focus the images correctly is measured in units called diopters.
Refractive surgery is the type of surgery that corrects these disorders and whose aim is that of dispensing with the use of glasses or contact lenses. The refractive surgeon is the ophthalmologist specialized in these interventions.
These four disorders can be treated by means of the refractive surgery, whatever the number of diopters. In any case it is the surgeon who must indicate if you are eligible or not to be treated and which is the most adequate technique in order to dispense with the use of glasses or contact lenses.
Among the most important factors that we, at the IOA, have to bear in mind to make this decision are:
That is the reason why at the IOA before giving advice to our patients we make an extensive evaluation. We estimate the quality of the eye with special tests such as topography of the cornea, the degree of refraction, measurements about the quality of the cornea or hysteresis and a complete ophthalmologic analysis. We also take into account your expectations by means of a personal interview, where the surgeon will reveal if the patient is adequate or not for the refractive surgery or simply advise him not to undergo an operation.
Our objective: the quality of your sight
It is the most frequent disorder and consists of an excess of diopters. This excessive power of the eye when focusing, thus making the near images permanently focused.
Myopics are called “short-sighted” people because they can only properly see the objects near them, while those further located are blurred.
It is the disorder opposed to myopia. A hypermetric eye has not enough diopters, so it is difficult to focus the furthest objects. Opposite to myopia, the eye of a youngster with hypermetropia can compensate the disorder, considering that he or she can properly see without glasses.
As age advances, this mechanism of compensation weakens and so is the sight, first with the nearer objects, later with the further located ones. The necessity of wearing glasses to focus the objects placed nearer to us occurs naturally once reached the 40 years old and it is called presbyopia or eyestrain.
It is basically a lack of symmetry on the surface of the eye (cornea).
There exist different types and degrees of astigmatism, but it often occurs along with myopia or hypermetropia, thus increasing the visual disorder caused by those ones.
At the IOA we have developed the refractive surgery sins 1992. The Excimer laser, the different types of intraocular lenses, the peripheral corneal incisions and the intracorneal rings are among the techniques which we use. Sometimes we recommend the combination of two or more of these.
2. Current correction of myopia, hypermetropia and astigmatism with a last generation laser.
The cornea is the transparent wall located at the rear part of the eye. Its function is to focus the images. The laser modifies the curvature of the cornea, so its capacity of focusing the images improves.
With its incredible precision, the Excimer laser permits to modify even the thinnest layers of the tissue. At the IOA two main tasks are carried out with the Excimer:
The LASIK refers to the most widely known Excimer technique to this day, due to its safety and efficiency. LASIK (Laser in situ Keratomileusis) consists of the modification of the shape of the cornea (queratomileusis: in Greek, “querato” meaning cornea and “mileusis” meaning to sculpt) through the application of the laser in its interior.
Prior to this, a thin layer of corneal tissue has been lifted, what is known as the “corneal flap”, which is later positioned and adheres without stitches. This way the discomfort that a patient may perceive is minimum and the recovery very quick.
LASIK Sub Bowman technique is an advanced version of the LASIK, whose difference resides in its even greater safety and number of corrected diopters.
The Advanced Surface Ablation technique (different types being: PRK, Epilasik and Laser), also carried out at out Institute, is an alternative to LASIK which presents advantages in some patients, and it consists of the application of Excimer laser right directly to the cornea, without any layer being lifted. The final result is equally satisfactory, although the period of recovery is longer.
The anesthesia used for these interventions is always topical (colirium) and it is not necessary to cover the eyes in the post-operatory.
The patient may feel the cold contact of the liquid, but he or she will not notice any discomfort or pain. With this anaesthesia, we prevent risks to appear at the same time that the period of recovery is virtually immediate.
The current laser equipment at IOA
In 2009 our centre has incorporated the cutting-edge refractive laser equipment Allegretto Eye-Q 400, the only one in the Canary Islands and revolutionary on its results.
In fact this avant-garde technology –wholly Europan (Erlagen, Germany)- is able to correct a diopter every 2,0 seconds. It is internationally regarded as the laser equipment that can correct the widest range of myopic and hypermetropic disorders as well as astigmatism, with treatments adapted to the necessities of every eye. And most important, it has sophisticated software that permits the preservation of the optical qualities of the eye, avoiding the undesired effects of other laser –especially in conditions of low luminosity.
Another outstanding characteristic that has influenced the incorporation of Allegretto to the centre is its capacity to treat patients with presbyopia (eyestrain caused by age) by means of the modification of the asphericity of the cornea. Allegretto is the only laser among the current ones able to do so, which opens a attractive future at the IOA to those patients already needing reading glasses.
We have already incorporated other new applications of this equipment that permit the improvement of visual quality. This is achieved with treatments guided by corneal topographies in patients with visual difficulties after a laser treatment or those who desire to improve their achieved vision after a refractive treatment.
3. How does the laser surgery works?
It may surprise you, but this is the easiest part of the process. The intervention takes a few minutes and the laser treatment just 2 seconds per diopter.
The technique we use permits the patient to stay with his or her eyes open while the laser works on the surface. The beam of light follows any movement that the eye may do at the moment.
If the patient moves the eye too much, the laser will stop automatically and the intervention will be resumed once the movement of the eye is controlled.
Here you have the answers to the most frequently asked questions:
Every case is studied deeply before the intervention so we can inform our patients of the realistic expectations the surgery may achieve. What is always offered and obtained is a good vision without glasses and contact lenses, but do not look for the “perfect vision”, because it does not exist outside our imagination.
The treatment after the age of 40
When a person reaches the age of 40, the sight is naturally weakened, so that every patient will need glasses sooner or later. In these cases, the patient is eligible to the simultaneous correction of presbyopia by means of Allegretto Eye-Q 400 laser. However, only after an evaluation before the surgery we will inform you about the realistic expectations of the process as well as confirm if you are a candidate for this treatment.
When will I be able of go back to normal life?
The answer is: in just a day, maybe two, with LASIK technique. This is the normal basis given our experience, although we will inform you about the precautions you must have regarding your eyes and you will have to use eye drops for a period of time, depending on the technique used. Ocassionally, it could be advisable to resume work a few days later. But the fact is that, in a normal basis, it just takes one day to completely see, without using any glasses, and gradually improving your vision.
How long do the results last?
Laser correction is stable, so the results obtained do not significantly vary with time. There will always be natural, little changes in the eye, but it is unlikely to need glasses once you have been treated.
What are the risks of the surgery?
It is important not to forget that every surgery has any risk, just like driving or taking a medicine. After the evaluation done before the surgery, you will have a much more realistic idea of the possibilities. Because of its results, the refractive laser surgery is probably the safest intervention that exists.
What can I do when the laser surgery is not enough?
There exist cases in which the corrective laser is not enough. For those, the Institute offers alternative techniques, as well as complementary ones, that permit the patient to forget about using glasses.
A patient with high level myopia or hypermetropia.
There is a decrease in the use of laser for those cases in which the levels of myopia and hypermetropia are really high. The implantation of intraocular lenses provides a better result to the eyes suitable for that kind of treatment. If you need more information about the implantation of intraocular lenses click here.