Pellucid Marginal Degeneration Research Paper

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INTRODUCTION. Pellucid Marginal Degeneration (PMD), also known as keratotorus [1], is a corneal ectasia that is often mistaken to be keratoconus, due to the similar features it shares [1, 2]. Pellucid Marginal Degeneration is a non-inflammatory disease that usually occurs bilaterally, however in some cases it may occur unilaterally [2]. Being a rare, progressive disorder, Pellucid Marginal Degeneration is characterised by the thinning of the inferior and peripheral portion of the cornea, although rarely the superior cornea may be involved [3]. This ocular pathology is presented between the ages of 20-40 years and causes a decline in visual acuity as a result of the irregular corneal shape. This may result in astigmatism. Distortion of vision…show more content…
The corneal thinning that occurs in Pellucid Marginal Degeneration is identified by 1- 2 mm of inferior peripheral thinning, spreading from the 4 o' clock to 8 o' clock positions [4]. This thinning represents the clinical feature of Pellucid Marginal Degeneration in view of it resembling a crescent shaped band [2]. The area of approximately 1-2 mm between the thinning cornea and the limbus remains unaffected and the centre of the cornea maintains its normal thickness [1,5]. The standard corneal sensation remains intact [6]. In some cases following corneal thinning, acute hydrops or corneal perforation may result. Abnormal corneal protrusion occurs above the region of thinning, this leads to irregular astigmatism. In Pellucid Marginal Degeneration the cornea is known as a "beer belly cornea". This is because the cornea has a more flattened shape and droops over the inferior limbus [2]. Pellucid Marginal Degeneration is differentiated from other corneal thinning disorders in that the area of thinning is avascular, without lipid deposition, clear, absence of corneal scarring and it lacks Rizutti's sign and Munson's sign

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