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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carotid artery obstructive disease, although infrequently diagnosed as a primary or contributing cause of neovascular glaucoma, can produce distinctive characteristics. Decreased perfusion of the ciliary body may decrease aqueous humor production. As a result, such eyes with neovascular glaucoma may occasionally be normotensive or even hypotensive. Fluorescein angiography may show an increased arm-to-retina time and leakage from the major retinal arterioles. Panretinal photocoagulation may not eliminate the anterior segment neovascularization because of anterior segment ischemia. Endarterectomy can significantly increase intraocular pressure as perfusion to the ciliary body returns to normal. These characteristics were found in two patients, a 67-year-old woman and a 49-year-old man, with diabetes and hypertension. In both cases cyclocryotherapy significantly reduced the intraocular pressure and the rubeosis iridis regressed.
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PMID:Neovascular glaucoma and carotid artery obstructive disease. 240 76

This experiment was performed to investigate the correlation between morphological changes of the corneal endothelium and clinical corneal edematous opacities after a procedure causing obstruction of bilateral long posterior ciliary arteries of the albino-rabbits. Shortly after the procedure, corneal endothelium became irregular on the anterior-chamber side and there were numerous lysosomal granules in the cytoplasm of corneal endothelial cells. On the third day, endothelial cells became necrotic and collapsed and a part of the cells peeled into the anterior chamber. Fibroblast-like cells and inflammatory cells were piled up in severely damaged areas of the endothelium. On the 11th day, the corneal endothelium developed again as a single layered structure on Descemet's membrane. It's seemed that corneal edema was induced as a result of severe damage corneal endothelium exposed to biochemical mediators such as prostaglandins released into the aqueous humor because the severity of corneal edema indicated some relation to changes in the concentration of prostaglandins in aqueous humor after anterior segmental ischemia.
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PMID:[Morphological study of corneal edema after anterior segment ischemia]. 281 80

Severe occlusive disease of the carotid artery may produce a rare syndrome of chronic ocular ischemia. Prolonged retinal hypoxia is associated with characteristic funduscopic changes and neovascularization of the iris, with subsequent obstruction of aqueous humor resorption. A case of neovascular glaucoma as a result of severe bilateral carotid occlusive disease and the pathophysiology involved are discussed. Definitive treatment consisted of carotid endarterectomy and aggressive control of intraocular pressure, including operative placement of a drainage implant in the anterior chamber of the eye. Seizure activity and an exacerbation of glaucoma developed after successful revascularization, exemplifying the derangements in cerebral and ocular function that may result from chronic hypoperfusion.
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PMID:Chronic ocular ischemia and neovascular glaucoma: a result of extracranial carotid artery disease. 318 12

The ocular effects of intravitreally injected copper sulfate solutions were studied in New Zealand white rabbits. These injections resulted in uveitis characterized by prolonged ocular hypotony, increased protein concentrations and decreased ascorbic acid concentrations in both the vitreous and aqueous humors, and an apparent decrease in the transport function of the anterior uvea. The extent and the duration of these effects were dose-dependent. The lower doses used, 3 or 6 micrograms of Cu as CuSO4 per eye, produced reversible inflammation. The highest dose, 30 micrograms of Cu per eye, also produced some signs of ocular chalcosis: hemorrhage, vitreous liquefaction, prolonged hypotony and local iridial ischemia. Six hours after the intravitreal injection of 6 micrograms of Cu as CuSO4 per eye, the Cu concentration in the vitreous humor increased to approximately 100 times that in the vitreous of control eyes, and began to decline only 3 days later, with a half-time of approximately 8 days. The Cu concentration in the anterior chamber of these eyes never exceeded 1 ppm and returned close to control values within 3 days. Based on these findings, factors that affect ocular trace-metal distribution and kinetics are discussed, as are reasons for the apparent difficulty in diagnosing the presence of Cu-containing intraocular foreign bodies on the basis of the Cu concentration of the aqueous humor.
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PMID:The pathophysiology of the ocular microenvironment. II. Copper-induced ocular inflammation and hypotony. 372 Aug 74

The involvement of platelet-activating factor (PAF) in the development of anterior segment necrosis after occlusion of the bilateral long posterior ciliary arteries was investigated in rabbits. With the progression of anterior segment necrosis, which was characterized by corneal edema and neovascularization, the contents of protein and total phospholipids increased in the cornea and aqueous humor, but not in the iris. PAF acetylhydrolase activity was significantly increased on the first postoperative day in the peripheral cornea and on the second day in the central cornea prior to the development of marked corneal edema and neovascularization, but it did not increase in the iris. The accumulation of newly synthesized PAF in the cornea reached a plateau level on the third postoperative day, which coincided with the progression of the corneal lesion. In the aqueous humor, PAF acetylhydrolase activity was increased by the induced ischemia, but no PAF was detected. The increased PAF acetylhydrolase activity may reflect adaptation to the participation of PAF in the progression of anterior segment necrosis.
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PMID:Corneal PAF acetylhydrolase increases in anterior segment ischemia in rabbits. 840 66

It is thought that dystrophic changes in the human aging anterior eye are due to lipid peroxidation in both the cortical and nuclear structures of the lens under the conditions of ischemia. These changes are often accompanied by only lens opacification (senile cataract-SC) or by formation of amorphous or fibrillar deposits in anterior eye, disturbances of eye hydrodynamics and lens opacification (pseudoexfoliation syndrome-PES). Our results suggest that the main reason of dystrophic changes in the tissues of the aging anterior eye is the disturbance of the haemato-ophthalmic barrier and that the plasma kallikrein-kinin system takes part in this disturbance. Penetration of plasma proteins, such as C-reactive protein, complement components, immunoglobulins and coagulation factors, from plasma into the aqueous humor is responsible for damaging epithelial structures of anterior eye and formation of pseudoexfoliative material. Using ELISA, the C-reactive protein, IgG and IgM antigens have been shown to localize on the surface of the opaque lenses. Presence of these complement binding proteins in the superficial lens structures as well as the high C3a concentration in the aqueous humor substantiates the pathogenic role of complement activation in the lenticular epithelium upon cataract and PES formation.
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PMID:Hageman factor and kallikrein in pathogenesis of senile cataracts and the pseudoexfoliation syndrome. 879 92

A 60-year-old woman developed anterior segment ischemia 1 week after an uneventful pterygium excision in the left eye. Corrected visual acuity fell from 20/20 to 20/200. Ophthalmic examination found keratic precipitates on the corneal endothelium, ++ cells in the aqueous humor, and necrosis of the lower half of the iris with posterior synechiae resulting in a fixed and distorted pupil. On therapy of topical corticosteroid eyedrops hourly and atropine eyedrops three times a day, the iridocyclitis resolved in 2 weeks. At the final examination 3 months after the surgery, the corrected visual acuity was 20/20. The atrophy of the lower half of the iris and posterior synechiae in the lower half of the pupil, giving the fixed and distorted pupil, were noted as sequelae. Iris fluorescein angiography revealed filling defects in the lower half of the iris but no leakage from iris vessels. Systemic evaluation was unremarkable except for mild hypertension. Doppler studies of carotid, ophthalmic, and central retinal arteries were normal. Mitomycin C, beta-irradiation and rectus muscle fixation sutures were not used. Only conjunctival dissection or episcleral cauterization were seen as possible causes of interference with the anterior segment blood supply. We believe this is the first report of anterior segment ischemia following pterygium surgery.
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PMID:Anterior segment ischemia following pterygium surgery. 924 17

Endothelin is a vasoactive peptide that has been shown to play an important role in vascular homeostasis. Recently, endothelin and its receptors have been found in ocular tissues where it appears to have a regulatory function. Endothelin is found in both the aqueous and vitreous humors and its concentration is elevated in glaucoma patients and in animal models of glaucoma. In the current review, the authors present information about the distribution of endothelin and endothelin receptors in the eye and the ocular actions of endothelins. Specifically, endothelin/aqueous humor dynamics, endothelin/nitric oxide interactions, endothelin and ischemia, and endothelin/optic nerve head effects. Observations concerning the potential role of endothelin in glaucoma pathophysiology is presented and discussed relative to its effects on the optic nerve head and in relation to glaucoma theories.
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PMID:Endothelin: is it a contributor to glaucoma pathophysiology? 1214 Apr 5

We report a case of a 48-year-old pseudophakic woman who presented 3 weeks after Heidelberg retinal angiography using intravenous sodium fluorescein 2%. Bilateral retinal vasculitis with severe retinal ischemia and extensive capillary dropouts had been diagnosed. Anterior segment examination revealed green staining on the silicone optic of the 3-piece SI-30NB intraocular lens (IOL) (AMO), with no cell or flare in the aqueous humor. The anterior and posterior capsules were not stained. The patient did not report dark vision, double vision, or altered color vision. The anterior and posterior IOL surfaces demonstrated an autofluorescence at the time of fundus photography, which persisted to the 6-week examination although there were no symptoms. This is suggestive of deposits of sodium fluorescein on the IOL surface following angiography.
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PMID:In vivo fluorescein staining of SI-30NB silicone intraocular lens. 1718 15

Neovascular glaucoma (NVG) is a severe form of glaucoma with devastating visual outcome attributed to new blood vessels obstructing aqueous humor outflow, usually secondary to widespread posterior segment ischemia. Invasion of the anterior chamber by a fibrovascular membrane initially obstructs aqueous outflow in an open-angle fashion and later contracts to produce secondary synechial angle-closure glaucoma. The full blown picture of NVG is characterized by iris neovascularization, a closed anterior chamber angle, and extremely high intraocular pressure (IOP) with severe ocular pain and usually poor vision.
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PMID:Neovascular glaucoma: etiology, diagnosis and prognosis. 1937 96


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