Myopia is a refraction defect which occurs when rays of light converge at a point before the retina, that is, the eye is longer than normal and the image is formed before the retina. It is therefore a defect which impedes seeing things correctly that are situated at a certain distance.
Myopia appears when the object that we see is formed just before the retina, provoking poor far vision and good near vision. This is on the of the principal vision defects that we suffer but advances in surgical techniques have allowed its effects to be eliminated.
As we have stated, patients with myopia see poorly at a distance but can see nearby well and require concave lenses in order to compensate the defect or refractive surgery.
In order to palliate this defect in patients under 50, the excimer laser technique is used. In patients with a normal corneal thickness, between 520 and 550 microns, two types of techniques can be used: Lasik or PRK. The ideal patients for this type of treatment are those who have a maximum of 5-6 dioptres, beyond which the technique is not advised. This same option is used to treat a type of astigmatism that is linked to myopia: myopic astigmatism.
In the case of young patients who have a corneal thickness of less than 500 microns, the use of the laser is discarded for its long-term contraindications. In these cases, it is advisable to choose to implant ICL intraocular lenses.
When we talk about patients over 50, other types of techniques come into play since myopia is also often accompanied by presbyopia. In these cases, the treatments must face both effects through the removal of the lens and the installation of multifocal intraocular lenses.
A myopic eye is an eye that is much larger than normal and in which the image is focused midway instead of reaching the back of the eye.
When myopia is actually operated on, what is actually done is to deceive the eye rather than make the eye smaller. The choices are to carve the cornea or place an intraocular lens that corrects the prescription, although the eye will always remain the same size. What this situation entails is that in the long term a myopic person will have the same likelihood of having the myopia-associated symptoms, and this should not be forgotten.
Severe myopia occurs when this elongation of the eyeball causes problems at the level of the fundus. “When we speak of severe myopia we do not refer to a specific number of dioptres; the diagnosis of severe myopia will be determined by possible alterations of the fundus.” And an eye with an above-average level of myopia may be susceptible to the following disorders:
- Retinal detachment
- Myopic maculopathies: these may be due to atrophy, neovascular and traction.
- Optic nerve alteration