Astigmatism is an optical aberration characterized by rays propagating into two perpendicular planes focusing at different distances, thus providing two different foci delimiting an intermediate area of focus called the Conoid of Sturm. This book discusses the types, diagnosis and treatment options of astigmatism. The topics include management of astigmatism in patients after a corneal transplant; power vectors; toric intraocular lenses for the correction of astigmatism during cataract surgery; irregular astigmatism management; and a comprehensive overview of preexisting astigmatism during phacoemulsification.