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The blood–ocular barrier is a barrier created by endothelium of capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. [1] It is a physical barrier between the local blood vessels and most parts of the eye itself, and stops many substances including drugs from traveling across it. [2]
Other factors can cause glaucoma, known as "secondary glaucoma", including prolonged use of steroids (steroid-induced glaucoma); conditions that severely restrict blood flow to the eye, such as severe diabetic retinopathy and central retinal vein occlusion (neovascular glaucoma); ocular trauma (angle-recession glaucoma); plateau iris; and ...
Kidney ischemia is a loss of blood flow to the kidney cells. Several physical symptoms include shrinkage of one or both kidneys, [19] renovascular hypertension, [20] acute renal failure, [19] progressive azotemia, [19] and acute pulmonary edema. [19] It is a disease with high mortality rate and high morbidity. [21]
Blood–air barrier – Membrane separating alveolar air from blood in lung capillaries; Blood–brain barrier – Semipermeable capillary border that allows selective passage of blood constituents into the brain; Blood–ocular barrier – Physical barrier between the local blood vessels and most parts of the eye itself
The optic nerve can be at very high risk for damage from insufficient blood supply due to swelling (from lack of oxygen) in a confined bony space resulting in a compartment syndrome. Restricted blood flow can lead to permanent damage to the optic nerve and result in blindness (often in both eyes).
A subconjunctival hemorrhage can often occur without any obvious cause or harm to the eye. A strong enough sneeze or cough can cause a blood vessel in the eye to burst. Hyphema is a result of blunt or penetrating trauma to the orbit that increases intraocular pressure, causing tears in the vessels of the ciliary body and iris.
Temporary vasospasm leading to decreased blood flow can be a cause of amaurosis fugax. [14] [15] Generally, these episodes are brief, lasting no longer than five minutes, [16] and have been associated with exercise. [10] [17] These vasospastic episodes are not restricted to young and healthy individuals. "Observations suggest that a systemic ...
The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in controlling hemorrhage and reducing acute blood loss. When blood vessels constrict, the flow of blood is restricted or decreased, thus retaining body heat or increasing vascular resistance.