![]() ![]() Both the horizontal and vertical dimensions of the cornea with pellucid marginal degeneration are measured using Castroviejo calipers to determine the selection of the trephine diameters (Figure 1). The surgical procedure is performed under general anesthesia. This technique keeps the full-thickness PK in the optimal central region of the cornea, thus decreasing the increased risk of graft rejection that is associated with a decentered PK in pellucid marginal degeneration. In this column, I describe the combined technique of crescentic deep anterior lamellar keratoplasty along with full-thickness penetrating keratoplasty in the surgical management of pellucid marginal degeneration. Additionally, the corneal sutures can pull through the thinned peripheral cornea and may result in corneal wound dehiscence that will often require surgical intervention. An uneven corneal surface will often result in suboptimal tear film spread over the corneal surface. In pellucid marginal degeneration, Terrien’s marginal degeneration and peripheral corneal melts, all have a thinned peripheral cornea, which can result in a mismatch of corneal thickness between the donor corneal button and the peripheral recipient corneal margins and a step-ladder edge-lift effect that should be avoided. Such a graft would place itself in the category of increased risk of graft rejection.įull-thickness PK requires adequate corneal thickness in the peripheral recipient corneal rim to establish proper donor-recipient approximation. This would require a large graft of 9 mm or more that is inferiorly decentered. While penetrating keratoplasty may be considered, it is challenging because the zone of corneal thinning and ectasia is located close to the inferior limbus. Visual rehabilitation requires surgical intervention when conservative treatments, including the use of contact lenses, have failed. Differential diagnosis includes keratoconus, keratoglobus, Terrien’s marginal degeneration, furrow degeneration and peripheral corneal melts, such as in Mooren’s ulcer. There is commonality in the histopathologic findings between keratoconus and pellucid marginal degeneration, namely, an area of stromal thinning with normal-appearing epithelium, endothelium and Descemet’s membrane with Bowman’s membrane disruptions. It is 1 mm to 2 mm from the limbus and extends horizontally for about 6 mm to 8 mm. The affected region inferiorly usually extends 1 mm to 2 mm in height. However, 10% of pellucid marginal degeneration cases are associated with keratoconus and 13% with keratoglobus, so it raises the question of whether pellucid marginal degeneration, keratoconus and keratoglobus are phenotypic variations of the same disease entity or different diseases. It stands second to keratoconus in the category of noninflammatory corneal thinning disorders. It usually presents in the second to fifth decade of life and has no sex or racial predilection. Pellucid marginal degeneration is an uncommon, nonhereditary, noninflammatory, bilateral, inferior crescentic peripheral thinning and ectatic disorder that can progress slowly over several years and result in significant visual deterioration. If you continue to have this issue please contact to Healio ![]()
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