images of pellucid marginal degeneration

#Images of pellucid marginal degeneration series

This corneal configuration corresponds to a tomographic map that shows the classical claw pattern (Figure 1).įigure 1. In PMD, corneal tomographic analysis reveals a flattening in the vertical meridian, inducing a significant against-the-rule (ATR) astigmatism and a significant steepening around the area of maximum thinning 3. Hence the need to calculate the depth of implantation depending on the thinnest point on the resumed passage, rather than on the thickness of the site of incision, in order to avoid deep corneal penetration. When intracorneal rings (ICRs) implantation is indicated in the management of PMD, caution should be paid to the location of the inferior segment, since it passes through the inferior thinned area. Accordingly, corneal cross linking should still be one of the treatment options. The management of PMD is unique since PMD is a progressive disease despite the fact that it is encountered in the third to fifth decade of life. Distinguishing between the two entities is of potential clinical importance since they differ markedly in prognosis and management. Similarities between PMD and keratoconus (KC) have led some ophthalmologists to consider PMD to be a peripheral form of KC 2, 3. Pellucid marginal degeneration (PMD) is an idiopathic, progressive, non-inflammatory, ectatic corneal disorder characterized by a peripheral inferior band of corneal thinning in a crescent-shaped pattern 1, although PMD cases with areas of superior thinning have been reported 2. The “bell” sign on the PM is a deferential diagnostic sign in PMD. Cone location does not relate to diagnosis. Conclusion: The claw pattern on the ASM is not a hallmark of PMD it can be seen in PLK. In group 2, the AEM in the BFS mode revealed the kissing birds sign in 2 eyes (18.2%), and the cone was central in 1 eye (9.1%), paracentral in 8 eyes (72.7%) and peripheral in 2 eyes (18.2%). PM showed the bell sign in 4 eyes (100%). In group 1, the AEM in the best fit sphere (BFS) mode revealed no kissing birds sign, and the cone was central in 1 eye (25%) and paracentral in 3 eyes (75%). The ASM, anterior elevation map (AEM) and PM were analyzed and compared to study the “kissing birds” sign, the “bell” sign, and cone location. Patients were studied using slitlamp biomicroscopy and Scheimpflug-based tomography (Pentacam HR).

Patients were distributed into two groups: (1) 4 eyes were considered PMD since they had inferior corneal thinning on both slitlamp biomicroscopy and PM (2) 11 eyes were considered as PLK since they did not show inferior corneal thinning.

Clinical and tomographic findings of 15 eyes (9 patients) that had the claw pattern of the anterior sagital map (ASM) were reviewed.

#Images of pellucid marginal degeneration series

Patients and methods: A retrospective descriptive case series was performed in Damascus University in 2011. Purpose: To study the tomographic features of pellucid-like keratoconus (PLK), and to report a new sign on the pachymetry map (PM) in pellucid marginal degeneration (PMD).