NNN Corneal Topography and Tomography Maps (Informative)

NNN.1 Introduction

Several ophthalmic devices produce curvature and/or elevation measurements of corneal anterior and posterior surfaces (e.g., maps that display corneal curvatures, corneal elevations, and corneal power, etc.). The principle methods used include reflection of light from the corneal surface (e.g., Placido ring topography) and multiple optical sectioning or slit beam imaging (e.g., Scheimpflug tomography). The measurements are mapped topographically as pseudo-color maps, and used extensively for diagnostic purposes by clinicians and to fit contact lenses in difficult cases. The underlying data from these measurements is also used to guide laser sculpting in keratorefractive surgery.