The main issue with prolonged reading, whether on electronic screens or printed material (and whether pre- or post- LASIK), is that the eyes get dry.
When we read something and become engrossed in the content, there is a tendency to forget to blink. This allows tears on the surface of the eye to evaporate without getting re-surfaced with a new layer of moisture.
To a lesser extent, prolonged near visual work may cause 'asthenopia' or a tired sensation around the eyes. This may be related in some cases to fatigue of the focusing muscles of the eye.
The simple solution to these problems is to take regular breaks when reading. After say, 30-40 minutes of near visual work, take a break for a few minutes and either look in the distance or close the eyes for a little while. Use artificial tears as necessary, and then return to the near visual work again.
Fortunately, if the spectacle power has been stable prior to LASIK, it will usually remain stable afterwards regardless of how much the eyes are 'strained'. I believe this is the main concern of many people, that 'straining' the eyes may cause the spectacle power to return.
A return of spectacle power, or what is otherwise known as 'regression' is generally related to factors other than 'strain' or excessive visual work. Some contributing factors to regression include having very high pre-existing spectacle power or being very young at the time LASIK was performed.
