In order to answer this question, it is best to define “success” in LASIK surgeries first. The goal of LASIK is to reduce or eliminate dependence on spectacles and contact lenses permanently by the surgical reduction or elimination of myopic power. Note that in some cases, the doctor may deliberately aim for slight under-correction. When successful, LASIK will allow you to carry out most of your daily activities without the need to wear spectacles or contact lenses. If spectacles are needed, they are usually worn at night and will be of considerably reduced power and thickness.
After careful evaluation and discussion, your LASIK doctor should be able to help you set reasonable expectations for your LASIK surgery. Note that results might not be as good for patients with considerably large refractive errors1. It is possible that after the surgery, some patients might still require glasses or contacts.
Given that LASIK eye surgery is a relatively new technology, first approved in 1998, there is currently no long term data available for the long term safety and effectiveness of LASIK surgery.
Perhaps a better question to ask is how to increase your success rate.
Careful evaluation of your circumstance as a candidate for LASIK surgery and detailed discussion with your doctor to manage expectations and get to understand the risks involved will be very helpful in risk management. Additionally, LASIK is widely considered safe and a popular surgery for a reason. The majority of the patients who have received the surgery have reported that they are happy with the results.