Incisional Keratotomy is used to reduce astigmatism, an unequal curvature of the cornea.
The cornea with astigmatism can be likened to a rugby ball, where one curve is long and the other short, rather than a basketball, where all curves are equal. The incisions are positioned peripherally, resulting in a cornea that is more round. Subsequently, the astigmatism is reduced and the uncorrected vision is improved.
Limbal relaxing incisions are now common practice amongst cataract surgeons, where it is often combined with the cataract operation to reduce pre-existing astigmatism. This ultimately results in better post-operative vision without glasses.