Keratoconus Case Study

General guidelines for screening for keratoconus:
1. Anterior and posterior elevation maps (Demirbas et al., 1998): In the anterior elevation map differences between the best fit sphere and the corneal contour of less than +12 μm are considered normal, between +12 μm and +15μm are suspicious, and more than +15 μm are typically indicative of keratoconus. Similar numbers about 5 μm higher apply to posterior elevation maps.

2. Anterior curvature map (Tomidokoro et al., 2000): The steepening of the cornea, irregular astigmatism, inferior steepening (I-S difference), location of steepest point and the thinnest point on the cornea may help in the diagnosis of keratoconus.
3. Pachymetry and thickness distribution maps (Ambro´sio et al., 2006):

It shows corneas that are not only thin, but with their thinnest portion significantly displaced. At times, the pachymetric distribution may be the most sensitive or earliest indicator of an ectatic disorder and may be abnormal in spite of a normal anterior corneal surface.
4-Thickness distribution maps (Ambrosio et al., 2002): Corneal thickness progression graph detects a suspect abnormal abrupt increase of the thickness values from the thinnest point towards the limbus. Patient lines (red) should be between the lines and follow the curve of the normative data. Progression index of the graph should be less than 1.2. The current corneal thickness progression graph shown in red is intersecting the normal graphs, and progressing below the inferior limit. The pachymetric progression is abrupt in as an important sign of ectasia.
5-Beilin-Ambrosio enhanced ectasia (Ambrosio et al.,