Many patients notice that their night vision changes. They notice haloes and starburst effects when they look at lights at night which, for the majority, is a point of note rather than something that causes any significant problems.
LASIK is performed with the aim of achieving a particular power for the eyes. The laser is very accurate in the way the treatment is delivered. It is important to note, however, that there is a range of outcomes and it is not possible to predict the exact outcome for each individual patient. The final result depends on a number of factors, including the patient's healing response and their own subjective response to the final result. A small group of patients elect to have further treatment when they would like the final power adjusted. This re-treatment is called an enhancement.