Ординатура / Офтальмология / Английские материалы / Step by Step Reading Pentacam Topography (Basics and Case Study Series)_Sinjab_2010
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Case Study 161 
Fig. 5.6R: The elevation back map. Very high elevations giving the shapeofacone,theseelevationsbecamemoreobviouswhenmanually adjusting the diameter of the BFS into 8 mm (red circle).
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Fig. 5.6S: The Keratometric power deviation map (KPD) .It is irregular and displays abnormal values. This means that the problem is bigger on the posterior surface than on the anterior surface, which is consistent with clinical keratoconus.
Case Study 163 
Fig. 5.6T: The Topometric map. All values are negative and most of them are highly abnormal (>-1). There is also big differences between meridians and between the vertical and horizontal averages (>0.3 difference).
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Fig. 5.6U: The keratoconus indices page. The red curves give an idea about the rapid progression of corneal thickness towards periphery. The average is very high. Almost all irregularity indices are highly abnormal. These findings give the reason for the diagnosis displayed in the diagnosis box “KK 3-4”.
Case Study 165 
Fig. 5.6V: Scheimpflug image. It is very clear that there is an inferior-temporal corneal thinning (white arrow).
•The elevation back map (Fig. 5.6Q): There are a large cone and abnormal values, which become more obvious when adjusting the diameter of the BFS manually on 8 mm (Fig. 5.6R red circle). Notice that the posterior elevations are much higher than the anterior,whichisconsistentwithclinicalkeratoconus.
•The Keratometric power deviation map (KPD): It is irregular and displays abnormal values (Fig. 5.6S).
•The Topometric map (Fig. 5.6T): Let’s go back first to the same map of the right eye (Fig. 5.6H) where all values in all meridians and on all circles are positive and abnormal indicating an oblate cornea, which is normal after Lasik treatment of myopia as we said before. So, we expect to see the same thing in the left eye map, but the truth is the opposite. As you see here, all values are negative and most of them are high, indicating a very prolate cornea, which is consistent with keratoconus and advanced keratoectasia. So we can say that in the very early stage of
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keratoectasia after myopic treatment, the cornea may still have the oblate shape, then it gets the prolate shape when the case progresses.
•The keratoconus indices page (Fig. 5.6U): Both diagrams indicate a very rapid increase in thickness and progression percentage towards the periphery; this is consistent with the very thick periphery and the relatively thin center of the cornea (see Fig. 5.6L). The average is very high (4.1) and most of the irregularity indices are abnormal. The diagnosis box displays keratoconus level 3 to 4.
•Figure 5.6V is one of the Scheimpflug image sectors, the ectatic part is very clear (white arrow).
Discussion
The right eye of the patient is slightly ectatic; there is small amount of astigmatism with very good UCVA and BSCVA. In my opinion the best management in this case is to crosslink this cornea because of the progressive deterioration of vision as the patient describes. Or at least, we have to observe the topography in 3 months periodicals.
The left eye is highly ectatic. The visual acuity is very low. Here we have to judge, is it better to do DALK, or to put rings and then do cross linking? In my opinion, taking the second decision will improve the irregularity of the cornea and will raise the cone towards the center of the cornea causing iatrogenic myopia and hence the need for more procedures such as phakic IOL. I am prone to choose the first choice (DALK) bearing the risk of PKP probability and hence graft rejection possibility.
Such cases will be discussed in my forthcoming book on Keratoconus, which will be published also by Jaypee Brothers.
Case Study 167 
CASE 7: KERATOCONUS
This is a keratoconus case. In this case I will present the topography and you will try yourself to read each map, writing notes and discussing the case depending on the skills you have learned, then you can read the discussion.
1.The four refractive maps (Fig. 5.7A).
2.The corneal thickness map (Fig. 5.7B).
3.The sagittal curvature front map (Fig. 5.7C).
4.The sagittal curvature front map after adjusting the color scale (Fig. 5.7D).
5.The sagittal curvature front map with the major axes projected (Fig. 5.7E).
6.The elevation front map (Fig. 5.7F).
7.The elevation back map (Fig. 5.7G).
8.The Keratometric power deviation map (Fig. 5.7H).
9.The Topometric map (Fig. 5.7I).
10.The keratoconus indices page (Fig. 5.7J).
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Fig. 5.7A: The four refractive maps.
Case Study 169 
Fig. 5.7B: The corneal thickness map.
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Fig. 5.7C: The sagittal curvature front map.