Corneal blood staining
Corneal blood staining is a severe ophthalmic complication that usually occurs as a result of long-standing hyphema, associated with increased intraocular pressure (IOP).
Corneal blood staining typically occurs after significant and prolonged hyphema, usually the result of ocular trauma, and especially in cases of chronically elevated intraocular pressure. The opacification consists of hemosiderin that has become embedded in the corneal stroma. It can take months, if not years for the cornea to clear, but with patience, it can clear completely. Unfortunately, the periphery clears first followed by the center.
minimally invasive glaucoma surgery
Congenital corneal blood staining secondary to hemorrhagic persistent fetal vasculature 
Predisposing factors that increase the risk of developing CBS include :
- Prolonged duration of hyphema
- A large amount of blood in the anterior chamber or total hyphema
- Dysfunction of corneal endothelium
- Increased intraocular pressure greater than 25 mm Hg for 6 days
- Injury to Descemet’s membrane
- Rebleeding 
Continuous overload with hemoglobin leads to necrosis of keratocytes and irreversible corneal blood staining.
Corneal blood staining represents deposition of hemoglobin initially in an extracellular location in the corneal stroma. Globules of erythrocytic breakdown products penetrate the discontinuous endothelium and intact Descemet's membrane.
In cases of acute corneal blood staining, electron microscopy revealed focal discontinuation of the corneal endothelium and degenerative changes. Descemet's membrane appeared intact and contained apparent hemoglobin globules, aw well as iron within Descemet's membrane, throughout the stroma, and within the epithelium. Eosinophilic deposits were also demonstrated throughout the stroma. The aggregates of hemoglobin and/or hemoglobin breakdown products primarily accumulate within stromal lamellae. Keratocytes showed extensive hemoglobin accumulations and contained small amounts of fine hemosiderin or ferritin granule.
In cases of long standing corneal blood staining, corneas presented evidence of endothelial damage with attenuation of cells, irregular spacing of nuclei, and absence of endothelium or degenerated endothelial cells were covered by intact endothelium. The blood-stained stroma contained relatively homogenous deposits of erythrocytic debris mostly within stromal lamellae, but also within keratocytes as in the acutely stained corneas. The cytoplasm of keratocytes also stained positively for erythrocytic breakdown products and hemosiderin, and were remarkable for extensive degenerative changes in contrast to keratocytes in areas of cleared cornea .
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
Clearing probably occurs by slow diffusion of hemoglobin and its breakdown products out of the corneal stroma.
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