Comparison of Methodologies Using Estimated or Measured Values of Total Corneal Astigmatism for Toric Intraocular Lens Power Calculation

Koch et al.1 reported that posterior corneal astigmatism has a mean magnitude of 0.30 diopters (D) with a steeper axis in the vertical meridian in more than 80% of eyes, and is relatively stable over the years. It is recognized that ignoring its power results in overcorrection in eyes with with-the-rule (WTR) astigmatism and undercorrection in eyes with against-the-rule (ATR) astigmatism.1,2 Traditionally, keratometers and topographers have evaluated only the anterior corneal surface. In most cases, a standard keratometric index of 1.3375 is used for converting anterior surface measures in

Source: Journal of Refractive Surgery - December 12, 2017 Category: Opthalmology Authors: Tiago B. Ferreira, MD, FEBOS-CR Source Type: research