Day to Day Clinically Relevant Corneal Elevation, Thickness, and Curvature Parameters Using the Orbscan II Scanning Slit Topographer and the Pentacam Scheimpflug Imaging Device

The introduction of different techniques and computerized devices into clinical ophthalmology has significantly improved our knowledge of the eyes, optics, and eye conditions. Today, corneal topography is performed with a wide range of devices that implement a variety of techniques. Advance computerized analysis systems provide us with simple and quick evaluation procedures, yet the sophisticated data and clinical information that is generated can only be interpreted with adequate knowledge of the system itself as well as the accepted normal ranges of various properties assessed with these systems. Two computerized topography systems that are in common use are the Orbscan (Bausch and Lomb Inc., Rochester, NY, USA) and the Pentacam (Oculus GmBH, Wetzlar, Germany). The Orbscan is a slit-scanning device and the Pentacam is Scheimpflug imaging device. In this review, we present a brief description of both technologies, the techniques implemented in each device and the acquisition process with each. This will be followed by a list of corneal parameters that need to be assessed in screening patients for refractive surgery. We will discuss how these parameters are displayed, how each parameter may serve as clinic criteria, and how data should be interpreted. We will also try to provide evidence regarding the accuracy of different measurements, and the comparability of the two devices.