If you have any view problems, you may have made some thoughts about theLaser intervention in the eye. But did you know that on average it lasts only 10 minutes? To improve the view, in fact, it takes about 20 seconds of laser and 10 minutes of other steps.
But how does a laser correct the eyes of the eyes, and how exactly does it work? As you can see from the 3D animations in the video, there are 3 refractive surgery techniques.
Owl defects: myopia, astigmatism and hyperopia
Before understanding how the laser operation works in the eyes, let’s try to understand How the eye works And what are the most common defects of the view: myopia, astigmatism And hyperopia.
When we look at an object, the light that is reflected by that object comes in our eye. The light then passes through the cornea – a small lens that represents more external curved layer – then enters the pupil (which is literally a hole and that’s why it is black) and then meets the crystallinea flexible lens that changes shape for focus close or distant objects, and finally affects the retinaa membrane located in the back of the eye where there are many cells that understand the light, i photojournalistwho send information through the optical nerve al brainwhich transforms them into images. And that’s how the view works.
For people who have no vision problems, the light converges in a single point said focal pointwhich falls right on the retina. For people who have vision problems, however, the focal point falls in other parts, and the view is compromised.
As you can see in the video, if the focal point falls before the retinayes it is myopiansand the distant objects are seen badly and the close ones. This flaw can be caused by several factors, including a more “outside” cornea – therefore with a smaller radius of curvature – or by a slightly longer eye.
If the focal point falls After the retinayes it is hyper -medropes. In these cases, generally, the distant objects are seen well and the close ones. The problem can be caused by a deformation of the cornea – in this case more “crushed” – or by a shorter eye.
If instead the light does not converge in a single point But in different points, we talk about astigmatismthat is, of a condition that worsens the view both from afar and up close. In this case, the cornea has a deformed curvature, therefore it does not form a perfect arch: that’s why you see blurred and/or distorted images.
How the laser operation is carried out: the difference between the techniques
To eliminate these defects, it is necessary to improve the curvature of the cornea, a thing possible with the laser operation.
To date there are 3 surgical techniques: the first is called PRKan English acronym that stands for cheratectomy coast. During the PRK there is a very thin surface layer of the eye, the corneal epithelium, and then we change the curvature of the cornea with the laser on the basis of the patient’s defect. Then one is inserted small protective lens which allows the corneal epithelium to regenerate. Within a week, a marked improvement of vision is already perceived.
In the PRK a use is used arousal laser: The name comes from the English “Excited dimer”, which means “Duero excited”. Dimero means couple, excited means that energy has been provided to him: in fact there is a couple of Argon and fluorine in the laser that is excited with an electric discharge. Once excited, the couple emits an ultraviolet light laser beam at 193 nm. This laser is able to nebulize the material of the cornea with extreme precisionand improves its curvature by correcting the defect.
The second technique, the Femolasikdoes not provide for the removal of the corneal epithelium: in this case a corneal epithelium flap is created with a laser with femtosecondi, the flap is raised, and then the cornea is always modeled with an arousal laser. At the end of the operation, the flap is reappeared, and in about 24h there is the improvement of the vision.
But what are these laser in Femtosecondi? They are infrared laser at 1053 nm which are applied with impulses in the order of the femtosecondi, and 1 femtosecondo is 0.000’000’000’000’000’001 s. These infrared light impulses are so smallwhich allow you to control the amount of energy in an extremely precise way to be transmitted and to create the engraving without damaging the external tissues.
The last technique is even more sophisticated, and does not provide for the removal or lifting of the corneal epithelium. The laser in Femtosecondi under the epithelium, directly on the cornea, to model it, creating a kind of lens which is then extracted thanks to an incision of 2 mm. This technique is called Smile (Small Incision Lenicule Extraction) and ensures a very quick recovery (24-48h), given that the intervention on the outside is practically null, but compared to the other two It cannot be used for hyperopia.
Before the intervention: patient analysis
Before the laser operation, doctors perform a accurate eye analysis work of the patient, collecting data to be able to set the tool to perfection.
In particular, theanamnesisthat is, a series of questions to understand the history of the eye: if there have been problems in the past, if the defect has remained stable over time, and so on. Then we move on to exams Real: the size of the cornea micrometer are measured with the optical coherence tomography, the pupil is verified on the basis of the light conditions with pupillography, and an endothelial microscopy is also made to control the health of the cells of the corneal endothelium.
Once all this precise data has been collected, sometimes you also do one Sympatitude simulation of the intervention to have an idea of the final result. All this process allows the surgeon to understand if the patient is suitable for intervention and what is the best technique for his specific case.
Like any operation, complications may arise, which in most cases are slightly entitled, such as the eye drynesswhich can be resolved with the application of artificial tears, or night vision problems that tend to decrease over time. The serious complications, on the other hand, are extremely rare for two reasons: primarily for the detailed pre-operative analysis, but above all for the extreme power of laser technology that intervenes with micrometric precision.
