Thanks to the flexibility of the laser, it is possible to intervene on visual defects by treating the entire surface of the cornea. Professor Paolo Vinciguerra, Head of Humanitas’ Ophthalmology Centre, speaks on this topic.
Flexibility of the laser
A sophisticated laser has the ability to treat the entire surface of the cornea. When we want to treat a visual defect, it is best to involve the entire surface of the cornea. Otherwise, when the pupil tends to widen at night, it will reach an area of the surface that has not been treated with laser.
To give an example, we will look at a patient in the condition of having a well corrected area for myopia, in which the vision is excellent by day. However, when the evening arrives, the pupil will widen, still intercepting shortsighted parts. In this way, the patient will find two images on the retina: one perfectly focused and one blurred, that of the myopic part.
This is because some lasers have the ability to have an optical zone ranging from 5 to 6.5 mm maximum. Instead, it would be advisable to have an ablation that reaches 10 mm and that connects the surfaces well, so as to make them one optical whole.
Recent research has shown that it was difficult for experts to recognize which eye had been operated on and which had not, precisely because the entire cornea had been remodelled. The flexibility of the laser makes it possible to successfully correct even very complex defects such as high astigmatism.
When these defects are treated on small optical areas, they do not have good stability over time. A result is achieved only in the short term because the problem tends to recur in the long run.
It may happen that years pass after a patient has undergone treatment before noticing that he or she still does not see as well as he or she would like. The laser has a specific program dedicated to repeat the treatment to correct these defects.
In retreatment, it is not always possible to completely eliminate the defects of the previous procedure and at the same time eliminate the use of glasses. Despite this, patients experience a significant improvement in visual quality.