The risks of customised femto-LASIK surgery are essentially the same as for any other LASIK surgery. Although it is not possible to list every single possible side effect or complication, in counselling patients for surgery we usually explain conditions that happen relatively commonly, as well as some that are very rare but serious.
Conditions that can occur after any refractive surgery include under/overcorrection, dry eyes and halos.
Under or overcorrections can occur due to individual variations in the response to laser treatment. Most of the time, the differences are minimal. Around 1% or less of the time, under or overcorrections can be of a larger degree and be bothersome. If enough corneal thickness remains, it could be possible to do an 'enhancement'/adjustment procedure to remove the little bit of remaining spectacle power at least 3 months from the original surgery.
Dry eyes are covered in a series of questions and answers in this forum, but suffice to say that the effects are usually temporary and things return to normal usually within a few weeks to a few months.
Halos are an extra glow of light around light sources with a dark background. It is quite common to see this in the early period after LASIK, and they usually get a lot less in a few weeks. Sometimes, especially where the pre-existing spectacle power was high, some amount of halos could persist in the long term -- but it is unusual for them to be so troubling as to prevent nighttime activities.
A very rare and serious complication is corneal infection after LASIK. While this is usually treatable with antibiotics, there is a possibility of scarring affecting vision afterwards. Another very rare complication is ectasia, where the cornea is too weak and bulges forwards, causing visual distortion. This can be stabilized with crosslinking treatment, and vision restored if necessary with contact lenses. But just to re-iterate, these conditions are extremely rare.
The above is by no means comprehensive and does not cover every possible problem with LASIK. If you have any pressing or specific concerns, you should discuss them in person with a doctor who specialises in these surgeries. This is the best way to get a realistic overview of the risks and benefits of such surgery.
