Krukenberg spindle is seen in pigment dispersion syndrome, a form of secondary open-angle glaucoma typically occurring in young to middle-aged adults with myopia, associated with posterior bowing of the midperipheral iris. The melanin pigment is located within the corneal endothelial cells and may also be found extracellularly on the posterior corneal surface (Fig 6-18). In pigment dispersion syndrome, melanin pigment is also seen in and around the endothelial cells lining the trabecular meshwork, correlating with the abnormally dark color of the meshwork observed gonioscopically (see Chapter 7, Fig 7-13). See also BCSC Section 10, Glaucoma.
Blood staining of the cornea may complicate hyphema when the intraocular pressure (IOP) is very high for a long duration; however, if the endothelium is compromised, blood staining can occur even at normal or low IOP (Fig 6-19). Histologically, red blood cells and their breakdown products (mostly hemoglobin and also small amounts of hemosiderin) are seen in the corneal stroma. The hemosiderin is located in the cytoplasm of keratocytes and may be demonstrated with iron stains such as Prussian blue.
Iron deposition in the corneal epithelium in keratoconus (Fleischer ring) was previously discussed (see Fig 6-17D).
See BCSC Section 8, External Disease and Cornea, for additional discussion of blood staining of the cornea as well as other forms of ocular surface iron lines.