Laser eye surgery correct the eyesight by reshaping the corneas of the eyes and correcting refractive errors to improve the focusing ability of the eyes.
However, like other surgeries, it can't be a guarantee for you that you will never suffer from previous vision problem any more permanently.
First of all, let's suppose it cure you at first treatment, you still have chance to develop myopia, hyperopia or astigmatism, if you don't pay attention to visual protection.
Second, 10 to 15 percent patient need re-treatment after their first surgery.
Therefore, laser surgery does help to improve your vision ,but it is not a guarantee for permannent perfect eyesight.
Well, in my opinion, laser eye surgery can be permanent, only if you have protected your eyes carefully. And as we know that when we are near-sighted, we can just take laser eye surgery, which can cure it, and make you have the perfect sight. On the other hand, if you do not take care of your eyes after the surgery, it will still make your sight low. For example, after the surgery, you should not let dirty things get into your eyes. Or it can infect your eyes, making your situation worse. Also, you should not take exercise in the first week. And after your eyes have recovered, you still need to control the time you use your eyes.
Whether the laser result is permanent or not depends on the prescription or your eyes. However, according to scientific research, only five percent of patients need further treatment after the laser eye surgery while the majority of the patients need no further treatment. If your prescription is high, there will be a great possibility for you to acquire further treatment. Patients with long sighted prescription and high astigmatism are more likely to have further treatment. Since the percentage of the people needing further treatment is very low, many clinics offer free re-treatment for them. So if you do need the re-treatment, you can get it free at the clinic where you had the laser surgery.