Scar tissue does not occur in general after clear cornea cataract surgery as the cornea is avascular (no blood vessels to bring the cells that produce a true scar).
When the opening is made on the white part of the eye, scarring does occur but is mild and usually of no significance.
The posterior lens capsule does become opacified (PCO: posterior capsular opacification) (ie, scar tissue forming faintly: more like a haze of epithelial cells and not true scar tissue). This occurs in about 20% of patients & may require a YAG laser capsulotomy (ie, laser used to open capsule: does not hurt). This is not uncommon with very high success rates and very low complications.