Relations between refractive astigmatism and corneal astigmatism

Purpose To investigate the relationship between refractive astigmatism and corneal (anterior and posterior) astigmatism in normal eyes. Methods We prospectively recorded refractive astigmatism and corneal astigmatism (Orbscan) of 500 healthy eyes (including ametropia) of 250 patients. Astigmatism data was analyzed using polar values (cylinder, axis) and rectangular coordinates (x,y) which respectively represent WTR/ATR component (Jackson 0°/90°) and oblique component (Jackson 45°/135°). Internal astigmatism and enantiomorphism (mirror-image symmetry between both eyes) were calculated. Results Anterior corneal cylinder showed higher correlation with subjective cylinder (r: 0.84 to 0.89 p 0.05). The relative proportion of the anterior corneal astigmatism in the subjective astigmatism increased with the subjective cylinder (r=0.54 p