Ocular Pathology

Use it to review eye pathology for Ophthalmology Board Review or OKAP. Anatomy and pathology of the human eye. Included solar-lentigo, phakomatous choristoma (phacomatous-choristoma), congenital hereditary endothelial dystrophy, Fuch's dystrophy, bullous keratopathy, conjunctival nevus, syringoma, primary acquired melanosis,carcinoma-in-situ, BIGH3 dystrophy, and other lesions seen in eye-pathology. The cornea, iris, lens, sclera, retina and optic nerve are all seen.

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Monday, February 26, 2007

Blood Staining of the Cornea

Definition: Corneal blood staining is defined as deposition of hemoglobin and its breakdown products in the cornea.
Incidence/Prevalence: Corneal blood staining occurs in the setting of traumatic hyphema, which has an incidence of 17/100,000. The majority of cases, about 80%, occur in males. The incidence of blood stained corneas in traumatic hyphema varies between 2-11%, but rises if there is a total hyphema to 33-100% in various studies.
Etiology: A combination of hyphema and resultant elevated intraocular pressure are believed to be important in the pathogenesis of blood stained corneas. A patient with hyphema and intraocular pressure greater than 25 mm Hg for 6 days is associated with greatest risk of corneal blood staining. Other predisposing factors are injury to Descemet’s membrane or endothelial damage. Some authors have stated that cytotoxic oxygen species are induced from the reaction of light with porphyrins. The notion that exposure to light may contribute to endothelial and keratocyte degeneration has been advanced.
Clinical: The clinical signs in the progression of corneal blood staining include fine yellow granules in the posterior stroma, yellow discoloration of the stroma, red to brown stromal color followed by shades of green, black, and grey. Note in the illustration a traumatic hyphema (number 1). The cornea peripheral to arrow 2 is white and that located more centrally is yellow to brown (blood staining). The lens is cataractous (number 3). Corneal blood staining may extend to Bowman's layer and even the epithelium in severe cases.
Clearance of the blood staining begins peripherally and progresses centrally, and can take up to 3 years. Notice

in the cross section of the cornea above that the blood staining is relatively absent at the periphery (arrow number 2) and most dense centrally. Similarly there is a clear demarcation between the anterior and posterior stroma (white arrow 3) indicative of more rapidly clearing posteriorly.
Pathology: Histopathology features erythrocytic debris and hemoglobin particles between corneal lamellae (arrows 4). In the illustration the hemoglobin particles have managed to make their way up above Bowman's layer (arrow 5). There may be degeneratiive endothelial cells and keratocytes (often seen in the late phases). Trichrome stain provides a dramatic contrast of the blood products in the cornea against the blue-green collagenous background (number 6). Frozen sections demonstrate fluorescence presumably corresponding to the hematoporphyrin derivative that is associated with toxicity. Some keratocytes in blood-stained corneas show hemosiderin and engulfed hemoglobin products. Areas of cleared cornea contain less hemosiderin. Clearing occurs peripherally first from the posterior stroma.
Treatment: Prevention is contingent on removal of the hyphema. Clot removal via an anterior chamber wash-out procedure is usually performed before 6 days of raised intraocular pressure (25 mm Hg or greater) and certainly with the first sign of blood staining. Options for management of the blood staining include observation, spontaneous clearance, or penetrating keratoplasty.
Prognosis: Cases of corneal blood staining secondary to hyphema have cleared spontaneously. One case cleared after 2 years without known intraocular pressure elevation. Many cases will have opacified corneas that require penetrating keratoplasty.

Gottsch JD et al. Arch Ophthalmol 1989;107:1497-500
Fraser C. Et. Al. Spontaneous resolution of corneal blood staining. Clin Experiment Ophthalmol 2006; 34: 279-80.

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