Although the elevation-based topographers evaluate both corneal surfaces depending on the principle of Scheimpflug image (Fig. 1.22), Placido-based topographers still can give more accurate data about the anterior corneal surface especially in case of corneal scars.

The new topographers combine both techniques to achieve the best corneal topography.

For full discussion of the curvature and elevation maps, please refer to my book “Corneal Topography in Clinical Practice” published by Jaypee Brothers 2009.

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