![]() ![]() ![]() In a topography map calculated without considering the refractive effect a sphere with a radius of, e.g., 8 mm will show the same power of 42.2 D at every point of its surface. Several factors must be taken into account in converting radii of curvature into power values:Ī sphere has the same radius of curvature at every position, but due to spherical aberration the refractive power is not the same everywhere.When radii are directly converted into power values according to the laws of Gaussian optics the refractive effect, as it is called, is not taken into account. ![]() The sagittal and tangential radii are calculated directly from the elevation data.All topography maps of the Pentacam ® are originally based on elevation data derived from Scheimpflug images and from the 3D model of the anterior eye segment that is calculated from those images. ![]()
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