Underwater vision after ICL? ICL after LASIK? LASIK twice?

It is not unusual for treatment of high prescriptions to result in quality of vision issues such as you describe. For this reason ICL surgery is a better option to start as it would create a better visual outcome for distance vision under all sitations. The existing issues would be best addressed at this time with a custom surface laser treatment to attempt to address issues of corneal irregularity after the original LASIK procedure. In our experience such treatments can substantially improve your situation.

*Would 2nd advanced LASIK cause
starbursts at night again?-->If by advanced LASIK you mean wavefront, yes,
it is possible that more LASIK, even wavefront, can cause starbursts
again. It can’t be predicted. If you have large pupils, or are having
a large correction, the chances of night side effects increase.

*Is ICL an option for someone who's
had LASIK done?--> LASIK will not change your candidacy for ICL. Generally speaking, if you were a
candidate for ICL pre-LASIK, you will likely be a candidate for ICL now
(assuming there is “enough” myopia to treat with an ICL... the minimum is 3D).

*Would it improve underwater vision
as well?--> In my experience, underwater vision (with a mask) will improve
commensurate with vision on land following these surgeries. Without a mask, it is unpredictable
what your vision will be like underwater.