Ординатура / Офтальмология / Английские материалы / Step by Step Reading Pentacam Topography (Basics and Case Study Series)_Sinjab_2010
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Case Study 151 
Fig. 5.6H: The Topometric map. All values in all meridians and on all circles are positive and abnormal indicating an oblate cornea.
152 Step by Step Reading Pentacam Topography
Fig. 5.6I: The keratoconus indices page. The red curve in the upper diagram begins within the normal range, and then it deviates rapidly. The progression percentage red curve is below normal in the lower diagram. This is consistent with the diagnosis shown “Post Corneal Surgery?” The average is high (1.7) and most of irregularity indices are abnormal, indicating irregular cornea.
Case Study 153 
Fig. 5.6J: Scheimpflug image. It is difficult here to assess the ectatic part of the cornea.
3.Studying each map:
•Corneal thickness map (Fig. 5.6L): The shape of this map is abnormal and irregular. The periphery is very thick and the central part is relatively thin, this is reflected on the thickness curves as will be shown in Fig. 5.6U. We cannot say here that the difference between the lower and upper points of the central 4 mm circle is normal, but we have to remember one of the important figures of Rowsey’s rule of 2’s: the peripheral thickness should not be >20 µ more than the central thickness, which is obviously absent in this case.
•The sagittal curvature front map (Fig. 5.6M): Shows a huge cone. But, to see the size of the central part of the cone, we have to adjust the color settings and we will have a better detailed picture (Fig. 5.6N). When projecting the major axes on this map, you can see clearly the abnormal distribution of the axes (Fig. 5.6O).
•The elevation front map (Fig. 5.6P): There are a large cone and abnormal values.
154 Step by Step Reading Pentacam Topography
Fig. 5.6K: The four refractive maps of the left eye. Keratoconus like topography with thin central cornea. The K-readings in the central 3 mm are abnormal with very small amount of astigmatism, which indicates that the cone is not central but peripheral. Q-value at the 6 mm circle of the cornea front is abnormal. Corneal thickness at the thinnest location is abnormal.
Case Study 155 
Fig. 5.6L: Corneal thickness map. Thin central cornea with more than 20 µ difference between the periphery and the center, this is abnormal according to Rowsey’s rule of 2’s.
156 Step by Step Reading Pentacam Topography
Fig. 5.6M: The sagittal curvature front map. There is a clear cone.
Case Study 157 
Fig. 5.6N: The sagittal curvature front map. The real cone can be better displayed after adjusting the color settings.
158 Step by Step Reading Pentacam Topography
Fig. 5.6O: The sagittal curvature front map. Abnormal distribution of the axes.
Case Study 159 
Fig. 5.6P: The elevation front map. Very high elevations giving the shape of a cone.
160 Step by Step Reading Pentacam Topography
Fig. 5.6Q: The elevation back map. Very high elevations giving the shape of a cone. Notice that the elevations on the back surface map are higher than those on the front surface map, which is consistent with clinical keratoconus where the ectasia is severer on the posterior surface than on the anterior surface.