Radial keratotomy (RK), developed by Russian ophtalmologist Svyatoslav Fyodorov in 1974, uses spoke-shaped incisions, always made with a diamond knife, to alter the shape of the cornea and reduce myopia or astigmatism; this technique is, in medium to high diopters, usually replaced by other refrective methods.
Mini Asymmetric Radial Keratotomy (MARK), developed by Italian ophtalmologist Marco Abbondanza in 1993 and improved in 2005. It consists of a series of microincisions, always made with a diamond knife, designed to cause a controlled cicatrisation of the cornea, which changes its thickness and shape. This procedure, if done properly, is able to cure the astigmatism and the first and second stage of the keratoconus, avoiding the cornea transplant.
Arcuate keratotomy (AK) is similar to radial keratotomy, but the incisions on the cornea are done at the periphery of the cornea. Arcuate keratotomy is used to correct astigmatism. Although most incisional procedures are replaced nowadays by Lasik, AK is still used in some special cases (correction of residual astigmatism after a keratoplasty procedure or during cataract surgery).
Limbal relaxing incisions (LRI) are incisions near the outer edge of the iris, used to correct minor astigmatism (typically less than 2 diopters). This is often performed in conjunction with an Intraocular Lens implantation.