Tangential or sagittal dioptric plots: is there a difference?

Most would agree that computerized videokeratoscopy is capable of providing a view of the cornea that is unmatched by any other method. However, which view should be used: tangential or sagittal? The answer is both. Each provides different information. It is clinically important to have a system that enables us to have both measurements to better understand the changes in corneal shape (tangential) as well as corneal power (sagittal) in pre- and post-refractive surgical procedures. This article attempts to provide a simplified explanation of the differences between the sagittal and tangential dioptric plot.