Ординатура / Офтальмология / Английские материалы / Elevation Based Corneal Tomography 2nd_Belin, Khachikian, Ambrósio_2011

(FIGURE 5) – Image of a patient with moderate keratoconus. The Scheimpflug image shows an inferior cone (right side of image) with corneal thinning and mild stromal opacity.

Figure 5

(FIGURE 6) – Image shows a patient with significant anterior stromal scarring secondary to old corneal hydrops. While the cornea appears thin, obvious conical protrusion is no longer present. At times, flattening of a previous cone will occur after resolution of hydrops secondary to corneal scarring.

Figure 6

(FIGURES 8A and 8B) – Horizontal and vertical cross-sectional Scheimpflug images of a patient with classic Pellucid Marginal Degeneration. The horizontal cut (3 degrees) shows a relatively normal corneal contour and no areas of focal thinning. In contrast to the horizontal section, the vertical cut (91 degrees) shows superior flattening, an inferior band of significant thinning and a dramatic alteration in the corneal contour at the band of thinning.

Figure 8A

Figure 8B

(FIGURE 9) – Scheimpflug image of a patient after LASIK demonstrating the residual bed thickness (RBT). In this case the RBT measured 260 microns centrally. The Pentacam was able to demonstrate that further enhancement surgery would not be advisable. In most cases, identification of the flap interface is not always possible.

Figure 9

(FIGURES 10A and 10B) – Anterior segment cross sectional image of a keratoconic cornea status-post INTACS insertion. The intracorneal segments can be clearly seen in the posterior peripheral cornea. The segment image is localized and magnified. The measurement feature of the Pentacam can be utilized to determine the depth of the segment. Here the measured depth of 396 microns matches very closely the planned depth of 400 microns.

Figure 10A

Figure 10B

(FIGURES 11A & 11B) – Scheimpflug cross sectional image of a cornea after successful Descemet’s Stripping Endothelial Keratoplasty (DSEK). DSEK is an additive surgical procedure where a thin posterior section (posterior stroma, Descemet’s, and endothelium) portion of a donor cornea is transplanted onto the back of the recipient’s cornea. Here the additive nature of the procedure is clearly seen as is the typically thinner central donor and thicker periphery (this accounts for the induced hyperopia). The host / donor interface, while visualized in the low power image (FIGURE 11A), is better examined in the higher power picture (FIGURE 11B).

Figure 11A

In FIGURE 11B (higher power magnification) the host / stroma interface is clearly seen as well as the thickened edge detail of the donor button. In this image the edge detection option is turned on. The red dotted line signifies the anterior corneal surface and the green dotted line the posterior surface. It is evident in this image that even with a fairly dense interface, the edge detection program of the Pentacam correctly located the posterior corneal surface.

Figure 11B

(FIGURES 13A & 13B) - These images illustrate a patient with corneal edema secondary to Fuchs dystrophy. FIGURE 13A (OD) illustrates corneal edema. In this image epithelial changes are also evident. The OS (FIGURE 13B) is status post full-thickness transplantation. The graft-host margin is clearly evident as well as the thick corneal periphery and the compact transplant. One can also appreciate some moderate graft host disparity at the wound margin.

Figure 13A

Figure 13B

(FIGURE 14) - This patient developed post LASIK ectasia in what appeared to be a normal pre-operative exam. Post-operative examination under high power Scheimpflug imaging revealed an inadvertent deep microkeratome pass of over 250 microns.

Figure 14