Keratoconus is a noninflammatory, bilateral but asymmetric central ectasia of the cornea. This produces myopia and irregular astigmatism. Histologically there first appears small breaks in the epithelial basement membrane and Bowman's layer. This is followed by anterior stromal scarring and central thinning. Iron can be deposited in the basal layers of the epithelium in a circle pattern (Fleischer ring). If acute rupture of Descemet's membrane occurs, sudden onset of stromal edema occurs (hydrops). With resolution of the acute hydrops, ruptures in Descemet's membrane can still be identified. Back to Cornea