Role of Hemidivisional Corneal Topographic Astigmatisms (CorTs) in the Regularization and Reduction of Irregular Astigmatism

Abstract

Purpose: To demonstrate how the concept of hemidivisional corneal topographic astigmatism (hemiCorT) enables the planning of hemidivisional corneal treatments to reduce irregularity and overall astigmatism. Methods: Whole-of-cornea corneal topographic astigmatism (CorT) is calculated from topography data derived from a corneal topographer or tomographer. The cornea is conceptually divided into 2 hemidivisions along the flat meridian of the CorT. For each hemidivision, hemiCorTs are calculated. The regularization treatment for each hemidivision is the treatment required to target the whole-of-cornea CorT, which is a symmetrical orthogonal corneal astigmatism. The regularization is then combin..