Alternative corneal astigmatism measuring technique successful

Corneal topographic astigmatism (CorT) is a successful alternative technique for measuring corneal astigmatism in irregular corneas.

Dr Noel Aplins et al., NewVision Clinics, Melbourne, Australia, conducted a retrospective study on the CorT method by obtaining axial power measurements in the right and left eyes using topography.

The astigmatism value was calculated for each Placido ring and the ring astigmatism values were combined by vector summation to form a new measure named CorT.

CorT was compared with other commonly used measures of corneal astigmatism by ocular residual astigmatism (ORA) and its standard deviation (SD). The flat meridian of the CorTcan be employed to conceptually divide the cornea into two hemidivisions. This means a CorT value was calculated for each corneal hemidivision.

The findings revealed that CorT had better correlation with manifest refractive cylinder than manual keratometry, simulated K , corneal wavefront (ORA 0.74 ± 0.36 D) and paraxial curvature matching.

The abstract can be found in the Journal of Cataract and Refractive Surgery.