Topography and tomography in the diagnosis of corneal ectasia.

For the modern day refractive surgeon, tomography has become an invaluable tool for selection of patients for refractive surgery; in addition it is essential for the diagnosis and treatment planning of ectatic disorders of the cornea. This review article attempts to compare the Scheimpflug with the Placido disc systems, stresses the value of elevation-based topography and the importance of posterior float. Finally, this article provides a comprehensive literature review of the most widely used tomographers, the Orbscan IIz, anterior segment optical coherence tomography, Pentacam, and Galilei Scheimpflug systems. Comparisons of the above tomographers provided in the available literature with respect to corneal elevation, corneal curvature (power) and pachymetry and calculation of intraocular lens power post-refractive surgery have also been discussed. [ABSTRACT FROM AUTHOR]