Intrastromal corneal ring segments (intacs) are used in all except
Intacs are not used for irregular astigmatism. Intacs consists of 2 semicircular rings made of PMMA and are used to flatten the cornea. It does not disturb vision. Intacs require atleast 400 microns of corneal stromal thickness. They are used most impoantly for keratoconus. It is also used for low myopia -1 to -3 D. But it has no role in irregular astigmatism which requires contact lenses for correction.
Post LASIK keratectasia
Keratoconus
Low myopia
Irregular astigmatism
Optics and Errors of Refraction