Most corneal topographers in clinical practice use Placido disk image capture technology and typically come in two different versions: either bowl type like the Oculus Keratograph; or cone type like the Medmont E300. There are other approaches to measuring topography, like slit scanning (B&L Orbscan) and Scheimpflug (Oculus Pentacam) systems, each with their own differences in methodology but essentially, they …
Capturing a wide field of view when measuring corneal topography
To optimize corneal topography image capture your aim is to image as much of the corneal surface as you can, which can be difficult as eyelids and eyelashes get in the way. Here it is worth pointing out that the image quality scores that some topographers provide can be misleading in this regard. It is possible to gain what might …
How large an area of topography image capture is needed for OrthoK lens fitting?
As much as possible is the correct answer, but as a rule, you should aim for at least 4.5mm of available curvature data from the center in all directions. If this is too difficult to achieve in the vertical meridian you should be fine with 3mm of data above and below the center, although this will depend on the orientation …
Eight steps to better corneal topography
Corneal topography is your main diagnostic tool for Orthok lens fitting. Get this right and everything else becomes so much easier. Do it badly, especially at first fit, and the rest of the journey will become harder. Fortunately, it’s not that hard a skill to learn and once you have the hang of it you will easily be able to …