I've used Ortho-k for 16 years, and I've absolutely loved them. I still confuse the heck out of people when I show or tell them I wear rigid contact lenses while sleeping. I've used glasses and dailies, and I without a doubt prefer Ortho-k. I do find it really weird that insurance doesn't cover it though - probably explains why they haven't become too widespread.

As an anecdote, it didn't work for me, unfortunately. Tried for 9 months, 3 different sets of lenses.

Apparently I don't have enough corneal tissue, which resulted in poor and increasingly bad vision starting every day around 3pm (~9 hours after removing lenses). My pupils also dilate surprisingly large, with no lenses being able to pull tissue over the entire dilated pupil, resulting in super nasty halos around light sources. The halos alone were bad enough that I wouldn't have been able to safely drive at night.

I am glad, though, that the attempt was completely, 100% side-effect free (except for my wallet). After a day or two, my vision returned to its terrible origin, with no halos or discomfort or anything.

I participated in the clinical trials for this and used them regularly between 2008-ish (it's hard to remember since I was in middle school) and 2015.

The results were remarkable but the contacts themselves where insanely uncomfortable.