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

The review discusses the molecular mechanisms of retinal damage, which are associated with retinal ischemia. Ischemia is one of the key factors determining the pathophysiology of many retinal diseases, such as diabetic retinopathy, glaucoma, anterior ischemic optic neuropathy, age-related macular degeneration, retinopathy of prematurity. Hypoxia and ischemia impair retinal neuronal energy metabolism, by launching a cascade of trigger reactions resulting in cell death. Oxidative stress, excitotoxicity, cell acidosis, inflammation, and others mechanisms acting in tandem are of considerable importance in ischemia. Neuronal apoptosis and neovascularization are the most important sequels of ischemia. Among all retinal neurons, ganglion cells are most susceptible to ischemia, which determines their early structural and functional changes in many ischemia-associated retinal diseases. The molecular mechanisms underlying the pathophysiology of ischemia-associated retinal diseases should be understood to substantiate and develop new therapy modalities.
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PMID:[Molecular mechanisms of retinal ischemia]. 2060 6

The pathophysiology of nonarteritic anterior ischemic optic neuropathy (NA-AION) is still imperfectly understood, but arterial hypertension seems to play a decisive role. Intolerance to hypoxia is defined as desaturation of hemoglobin more than 15% at rest and/or elevation of blood pressure at rest or after exercise over 20mmHg in hypoxia. We report the case of a 66-year-old woman who presented bilateral NA-AION during a trek at high altitude (>2500m). The etiological check up was negative. Due to the circumstances of occurrence, we requested a tolerance to hypoxia test, which was positive. In this case, the combined effects of altitude and effort probably led to prolonged desaturation of oxyhemoglobin associated with an excessive blood pressure increase upon exercise leading to ischemia of the optic nerve head. This case showed the value of a systematic search for hypoxia tolerance in patients with nonarteritic anterior ischemic optic neuropathy occurring during a situation of prolonged hypoxia (long-distance flight, high altitude).
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PMID:[Role of intolerance to hypoxia in the occurrence of anterior bilateral ischaemic optic neuropathy at high altitude]. 2109 3

Interferon (INF)-associated retinopathy occurs in 15-64% of INF-treated patients, transforming this complication into a significant risk for visual impairment. This retinopathy has been described as an ocular complication with a variable clinical course, usually benign and asymptomatic. The most common findings are hemorrhages and cotton wool spots. Atypical ocular side effects include branch or central retinal artery occlusion, central retinal vein occlusion, anterior ischemic optic neuropathy, optic disc edema, neovascular glaucoma and vitreous hemorrhage. Some case series suggest that in most cases the clinical course of the disease is benign, asymptomatic and without long-term consequences and therefore do not recommend any specific treatment; they only recommend the discontinuation of INF in patients with severe manifestations or risk factors such as hypertension or diabetes mellitus. The case reported here presents an atypical manifestation of INF-associated retinopathy consisting of a mixed retinal vascular occlusion (arterial and venous), associated with severe occlusive inflammatory microangiopathy with extensive retinal damage by ischemia and a torpid clinical course despite suspension of treatment. These varieties of occlusive vascular events have not yet been found simultaneously in the literature and neither with an unfavorable clinical course. Although the clinical course of INF-associated retinopathy in most cases is asymptomatic, there may be complications with risk to vision, which is less common. The magnitude and severity of the consequences associated with INF therapy are to be determined in prospective further studies.
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PMID:Mixed vascular occlusion in a patient with interferon-associated retinopathy. 2132 40

Pathological tortuosity of the carotid arteries is a cause of not only cerebral circulatory disorders, but also visual impairments. There are nonspecific and specific signs of circulatory disorders in the anterior ocular segment - bulbar conjunctiva. In pathological tortuosity of the carotid arteries visual impairments are divided into transient, acute, and chronic. Transient impairments include amaurosis fugax, ocular and orbital pains; acute impairments involve ischemic uveitis, acute retinal ischemia, acute ischemic oculopathy, anterior and posterior ischemic optic neuropathy; chronic visual impairments comprise ischemic uveal, chorioidal, retinal, and ocular neuropathy. Noninvasive ultrasound techniques involving carotid duplex scanning and color Doppler mapping of ocular and orbital vessels are the most objective studies of patients with visual impairments in pathological tortuosity of the carotid arteries.
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PMID:[Changes in the organ of vision in pathological tortuosity and atherosclerotic stenosis of the carotid arteries]. 2132 97

Autophagy is the major intracellular degradation pathway that regulates long-lived proteins and organelles turnover. This process occurs at basal levels in all cells but it is rapidly upregulated in response to starvation and cellular stress. Although being recently implicated in neurodegeneration, it remains still unclear whether autophagy has a detrimental or protective role. In this study, we investigated the dynamics of the autophagic process in retinal tissue that has undergone transient ischemia, an experimental model that recapitulates features of ocular pathologies, including glaucoma, anterior ischemic optic neuropathy and retinal vessels occlusion. Retinal ischemia, induced in adult rats by increasing the intraocular pressure, was characterized by a reduction in the phosphatidylethanolamine-modified form of LC3 (LC3II) and by a significant decrease in Beclin-1. The latter event was associated with a proteolytic cleavage of Beclin-1, leading to the accumulation of a 50-kDa fragment. This event was prevented by intravitreal treatment with the non-competitive N-methyl-D-aspartate antagonist MK801 and calpain inhibitors or by calpain knockdown. Blockade of autophagy by pharmacological inhibition or Beclin-1 silencing in RGC-5 increased cell death, suggesting a pro-survival role of the autophagic process in this neuronal cell type. Altogether, our results provide original evidence for calpain-mediated cleavage of Beclin-1 and deregulation of basal autophagy in the rat retina that has undergone ocular ischemia/reperfusion injury.
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PMID:Calpain-mediated cleavage of Beclin-1 and autophagy deregulation following retinal ischemic injury in vivo. 2149 Jun 76

Giant cell arteritis (Horton's disease) is an inflammatory panarteritis occurring most frequently in the elderly. Its common ocular manifestations are anterior ischemic optic neuropathy, choroidal ischemia and central retinal artery occlusion. We describe a case of Horton's disease revealed by a retinal detachment, optic neuropathy and severe choroidal ischemia. Prompt treatment with corticosteroids led to preservation of vision and resolution of the retinal detachment. This observation of a retinal detachment revealing a giant cell arteritis had not been yet reported in the literature.
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PMID:[Exsudative retinal detachment indicative of a giant cell arteritis. A case report]. 2156 51

Arteritic anterior ischemic optic neuropathy (AAION) is an acute ischemia of the posterior ciliary arteries and/or ophthalmic artery due to inflammation. Therapy is immediate intervention with systemic steroids, especially to protect against vision loss in the other eye. The addition of a potent vasodilator to the steroids could help restore ocular blood flow and improve visual acuity. The objective of the current report was to present the use of prostaglandin E(1) (PGE(1)) - a powerful vasodilator of the microcirculation - in the treatment of AAION. Two patients with AAION were treated with intravenous steroids and PGE(1). The visual acuity improved from 4/50 (less than 20/200) to 6/10 (20/35) in one patient and from 1/50 (20/400) to 1/10 (20/200) in the second patient. The visual fields in both patients maintained small central islands of vision. No complications due to the use of PGE(1) were seen. Intravenous PGE(1) should be considered in addition to steroids in cases of AAION to immediately restore blood flow to the optic nerve and improve visual acuity while the steroids reduce the inflammation.
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PMID:Arteritic anterior ischemic optic neuropathy treated with intravenous prostaglandin E(1) and steroids. 2247 19

This review will highlight a new technology and recent insights into measuring retinal oxygen saturation in several ophthalmic diseases. A growing body of evidence suggests that disturbances in retinal blood flow and oxygenation are related to several retinopathies and glaucoma, which can severely impair vision. The retinal oximeter may allow researchers and physicians to gain deeper insights into retinal physiology and clarify the impact of ischemia on retinal health and function. There are two commercially available systems to measure retinal oxygen saturation: the Oxymap retinal oximeter (Reykjavik, Iceland) and the Imedos Systems UG (Jena, Germany). In this review we will focus on the results obtained with Oxymap. Direct and non-invasive measurement of retinal oxygen saturation have potentially useful diagnostic and therapeutic indications in various eye diseases such as diabetic retinopathy, age-related macular degeneration, central retinal vein and artery occlusion, anterior ischemic optic neuropathy and retinopathy of prematurity. Despite several limitations, oxygen saturation assessment in the retinal vessels is a significant advancement in the understanding of ocular diseases. Nevertheless, further studies are needed to validate the use of oximetry in retinal vasopathies and glaucoma.
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PMID:Oximetry: recent insights into retinal vasopathies and glaucoma. 2255 Jul 81

Sectoral choroidal ischemia is a classic sign of giant cell arteritis, although the latter is more typically associated with anterior ischemic optic neuropathy or central retinal artery occlusion. We report the case of an acute choroidal ischemia in a 68-year-old, one-eyed patient, who presented with deterioration of visual acuity and metamorphopsia in his left eye (his right eye was counting fingers due to high myopia). Fundus examination revealed retinal pigment epithelium (RPE) alterations and slow choroidal perfusion on fluorescein angiography. Macular Optical Coherence Tomography (OCT) showed a total disruption of the photoreceptor layer. Although prompt corticosteroid therapy preserved some vision, secondary macular retinal pigment epithelial changes limited the visual outcome. No other ophthalmological signs were observed in follow-up.
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PMID:[Acute sectoral choroidal ischemia: a case report]. 2298 23

Acute ischemic lesions of the posterior optic nerve and optic tract can produce a variety of visual field defects. A 71-year-old woman presented with acute hemianopia, which led to rt-PA thrombolysis for suspected posterior cerebral artery ischemia. 3-Tesla cMRI, however, revealed the cause to be an acute posterior ischemic optic neuropathy. Cases like this may be more common than thought and quite regularly overlooked in clinical practice, especially when there is no high-resolution MRI available. This case strengthens the importance of repeat MR imaging in patients with persistent visual field defects.
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PMID:Acute posterior ischemic optic neuropathy mimicking posterior cerebral artery stroke visualized by 3-tesla MRI. 2318 70


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