Keratoglobus

Abstract

Keratoglobus is a rare noninflammatory corneal thinning disorder characterised by generalised thinning and globular protrusion of the cornea. It was first described as a separate clinical entity by Verrey in 1947. Both congenital and acquired forms have been shown to occur, and may be associated with various other ocular and systemic syndromes including the connective tissue disorders. Similarities have been found with other noninflammatory thinning disorders like keratoconus that has given rise to hypotheses about the aetiopathogenesis. However, the exact genetics and pathogenesis are still unclear. Clinical presentation is characterised by progressive diminution resulting from irregular corneal topography with increased corneal fragility due to extreme thinning. Conservative and surgical management for visual rehabilitation and improved tectonic stability have been described, but remains challenging. In the absence of a definitive standard procedure for management of this disorder, various surgical procedures have been attempted in order to overcome the difficulties. This article reviews the aetiological factors, differential diagnosis, histopathology, and management options of keratoglobus.

Figure 1

Slit-lamp photograph of a patient with bilateral keratoglobus (a) showing thinning (maximum at the periphery) and bulging of cornea, (b) after ‘tuck-in' lamellar keratoplasty (TILK).

Figure 2

Photomicrograph of (a) lamellar corneal button showing diffuse stromal thinning (stain: haematoxylin and eosin, × 40), (b) central cornea showing thinned corneal epithelium with intraepithelial oedema and separation of epithelium from epithelial basement membrane. There is discontinuity of Bowman's layer (marked between the two red arrows and two black arrows; stain: haematoxylin and eosin, × 400).