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

Some of the basic underlying processes in the development of diabetic retinopathy include changes in the walls of retinal vessels, with occlusion and leakage. These result in edema, hemorrhage, hard exudates, plaques, and ischemia, leading to neovascularization. When proliferative retinopathy supervenes, it may result in complete blindness. Internists and family practice physicians should be alert for early signs of diabetic retinopathy. Ideally, diabetic patients should have their eyes examined yearly by an ophthalmologist. A fundus examination without dilation and usually without acuity testing rarely detects proliferative or early background retinopathy. Multicenter studies have shown that photocoagulation of new vessels with the argon laser may significantly reduce the incidence of severe visual loss. This treatment method has the potential of reducing the incidence of diabetic blindness by 60% to 80%. Photocoagulation is not a "cure" for diabetic macular edema; when used judiciously, however, it can sometimes further reduce visual loss caused by this common disease. The course of diabetic retinopathy in individual cases is unpredictable. After photocoagulation, some patients cannot see as well as before, though in others the progress of the disease is arrested. There is a conservative concern about a procedure that destroys retinal tissue in the hope of limiting the progression of the disorder. Yet photocoagulation appears to be the only alternative until a better treatment is developed through basic research.
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PMID:Diabetic retinopathy: a leading cause of new blindness. 265 2

Ten patients (11 eyes) with sickle-C hemoglobinopathy with complications of proliferative sickle retinopathy were treated using pars plana vitrectomy with or without the use of a scleral buckle. Postoperative visual acuity was improved in ten of 11 cases. Three cases of retinal detachment were managed by internal vitreoretinal techniques alone without the use of a scleral buckle. Although exchange transfusions were used in only five of the 11 cases, no cases of recognized anterior segment ischemia occurred during the postoperative course of these patients. Because of exchange transfusion risks and awareness of intraoperative and postoperative measures to reduce this complication, the use of exchange transfusions probably should be discontinued as prophylaxis for vitreoretinal surgery in these patients.
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PMID:Pars plana vitrectomy in the management of complications of proliferative sickle retinopathy. 319 May 40

Patients with diabetes mellitus and coronary artery disease are thought to have painless myocardial ischemia more often than patients without diabetes. We studied 50 consecutive patients with diabetes and 50 consecutive patients without diabetes, all with ischemia, on exercise thallium scintigraphy to show the reliability of angina as a marker for exertional ischemia. The two groups had similar clinical characteristics, treadmill test results, and extent of infarction and ischemia, but only 14 [corrected] patients with diabetes compared with 34 [corrected] patients without diabetes had angina during exertional ischemia. In diabetic patients the extent of retinopathy, nephropathy, or peripheral neuropathy was similar in patients with and without angina. Angina is an unreliable index of myocardial ischemia in diabetic patients with coronary artery disease. Given the increased cardiac morbidity and mortality in such patients, periodic objective assessments of the extent of ischemia are warranted.
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PMID:Angina and exertional myocardial ischemia in diabetic and nondiabetic patients: assessment by exercise thallium scintigraphy. 334 50

This article presents the clinicopathologic features of five patients with ocular involvement secondary to carotid artery disease. Three patients had the features of hypotensive retinopathy and two had panocular ischemia. In demonstrating the possible ocular and nonocular sequelae of carotid artery disease, this study stressed the importance of the recognition of the variable ocular features associated with carotid artery occlusive disease.
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PMID:Ocular features of carotid occlusive disease. 357 93

A frequently cited theory for the pathogenesis of neovascularization in diabetic retinopathy is that retinal hypoxia and/or ischemia release a factor which stimulates neovascularization. To the authors' knowledge, there is no direct in vivo evidence in the human proving this theory. One hundred and twenty-two diabetic subjects were studied to see whether worsening retinopathy was associated with changes in conjunctival oxygen tension (pO2). Diabetics without retinopathy had a conjunctival pO2 which was similar to an age-matched normal population. Diabetics with only background retinopathy had a significantly lower conjunctival pO2 than those without retinopathy (P less than 0.01). Diabetics with proliferative retinopathy showed a conjunctival pO2 that was significantly lower than either of the first two groups (P less than 0.05). The lowest value of all was found in patients with rubeosis iridis. Duration of diabetes alone did not correlate significantly to conjunctival pO2. These findings support the hypoxic theory of diabetic neovascular retinopathy.
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PMID:Conjunctival hypoxia in diabetes mellitus. 375 67

Experimental renovascular malignant arterial hypertension was produced, by modified Goldblatt's procedures, in 60 rhesus monkeys, and hypertensive fundus changes were studied in detail (by serial ophthalmoscopy and fluorescein fundus angiography in all monkeys on a long-term follow-up, and pathologically in 29 eyes). In hypertensive choroidopathy, retinal pigment epithelial (RPE) lesions and serous retinal detachment (RD) were the classic ophthalmoscopic lesions, whereas fluorescein fundus angiography and histopathologic studies revealed marked abnormalities in the choroidal vascular bed, in addition to the changes in the RPE. The RPE lesions could be subdivided into initial acute focal lesions (due to focal RPE infarction), and degenerative lesions, which developed later and were progressive in nature, maximally involving the macular and peripheral regions of the fundus. The RD developed most commonly in the posterior pole and infrequently involved the peripheral retina. The choroidal vascular bed showed impaired circulation and extensive occlusive and ischemic changes. These studies revealed that hypertensive choroidopathy is as important a fundus change as hypertensive retinopathy. The pathogenesis of hypertensive choroidopathy is discussed in detail; the evidence indicates that it is due to choroidal ischemia, and that hypertensive choroidopathy and retinopathy are two independent and unrelated manifestations of renovascular malignant hypertension.
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PMID:Fundus lesions in malignant hypertension. VI. Hypertensive choroidopathy. 380 99

The retinal circulation of 35 patients (age, 30 to 71 years) with symptomatic internal carotid occlusion (22 cases) or severe inaccessible stenosis (13 cases) was studied both before and after superficial temporal to middle cerebral artery (STA-MCA) bypass surgery using ophthalmodynamometry (ODM) and intravenous fundus fluorescein angiography (IVFA). Ninety-four per cent of the patients were found preoperatively to have funduscopic findings or symptoms indicative of ocular ischemia. ODM values were abnormal preoperatively in 32 of 35 patients (91%), and improvement in ODM values for the ipsilateral eye was noted postoperatively in 25 patients (71%). ODM values obtained during the early (less than 3 months) and late (greater than 3 months) postoperative periods were significantly improved when compared to the preoperative values. IVFA values were abnormal in 25 of 29 patients (86%) preoperatively, and significant improvement was noted in 22 of 25 patients (88%) postoperatively. Preoperative patients with normal fundus examinations (10 cases) had significantly better values for IVFA and ODM than patients with venous stasis retinopathy. The findings of the study showed that STA-MCA anastomosis is beneficial in treating retinal ischemia secondary to ipsilateral severe inaccessible carotid artery stenosis or occlusion.
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PMID:Improvement in the retinal circulation after superficial temporal to middle cerebral artery bypass. 399 Sep 31

Venous stasis retinopathy and ischemic oculopathy are ocular manifestations of ischemia in the distribution of the carotid artery. While not as common as transient monocular blindness or retinal arterial emboli, they are readily recognizable and indicate the presence of severe, often bilateral, carotid occlusive disease. Patterns of occlusion vary but usually include complete occlusion of at least one common or internal carotid artery, often accompanied by occlusion or narrowing in the opposite carotid system. The ocular findings in venous stasis retinopathy and ischemic oculopathy indicate ongoing ocular ischemia and may progress to intractable neovascular glaucoma. Therapy, individualized for the specific pattern of occlusive changes, may be directed toward prevention of stroke or may be indicated primarily for the reversal of ocular ischemia and prevention of blindness secondary to neovascular glaucoma.
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PMID:Chronic ocular ischemia and carotid vascular disease. 402 85

Macrovascular and microvascular complications of diabetes may be associated with different environmental factors. To investigate this further, a prevalence study of 503 Mexican type II diabetic subjects was carried out while their patterns of nutrition were constrained by government food subsidies. Average daily dietary intakes were 1866 kcal; 46.5% as carbohydrate, 13.7 mmol cholesterol, 8.7 g fiber, and a polyunsaturated/saturated fat ratio of 0.98. With respect to macrovascular disease, 49.3% of patients had evidence of peripheral vascular disease, and 21.6% myocardial ischemia, 6.0% angina, 10.8% EKG evidence of ischemia, 4.8% EKG evidence of myocardial infarction. Only 1.2% (six patients) had a clear history of completed stroke, and all were hypertensive. Six patients had also undergone amputations for diabetic gangrene. Tabulation of the means of clinical characteristics according to presence or absence of myocardial ischemia showed that higher cholesterol, calorie, and fat intake, higher mean blood pressure, higher serum cholesterol, and serum triglyceride levels were found in those with myocardial ischemia. Patients with peripheral vascular disease were more commonly smokers. Stepwise logistic regression revealed significant positive associations between myocardial ischemia and dietary cholesterol, serum cholesterol, and mean blood pressure. In contrast, the presence of peripheral vascular disease was significantly related only to smoking and retinopathy. There were no associations between macrovascular complications and duration of diabetes in the multivariate analysis, and they occurred with equal frequency in men and women. Prospective studies of atherosclerosis in maturity-onset diabetes should assess and seek to modify dietary cholesterol, serum cholesterol, and hypertension.
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PMID:Association of differing dietary, metabolic, and clinical risk factors with macrovascular complications of diabetes: a prevalence study of 503 Mexican type II diabetic subjects. I. 609 28

A prospective natural history study was conducted in 721 eyes with various types of retinal vein occlusion (RVO) to determine the incidence of various types of ocular neovascularization (NV) and the factors that influence the development of ocular NV. The material was 360 eyes with central retinal vein occlusion (CRVO), 97 eyes with hemi-CRVO, and 264 eyes with branch retinal vein occlusion (BRVO); these cases were further subdivided into six groups for logical data analysis: nonischemic CRVO (venous stasis retinopathy-VSR, 282 eyes), ischemic CRVO (hemorrhagic retinopathy-HR, 78 eyes), hemi-VSR (66 eyes), hemi-HR (31 eyes), major BRVO (191 eyes) and macular BRVO (73 eyes). Ocular NV attributable to RVO was seen only in HR, hemi-HR, and major BRVO. In HR the anterior segment was the major site of NV, with iris and angle NV and neovascular glaucoma (NVG), while in hemi-HR and major BRVO the retina and optic disc were the major sites of NV. The principal factor influencing the development of ocular NV in RVO seems to be the severity and extent of retinal ischemia, while duration of follow-up since onset also plays an important role in determining the incidence of ocular NV. The findings and subject of ocular NV in RVO are discussed in detail along with a review of the pertinent literature.
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PMID:Ocular neovascularization with retinal vascular occlusion-III. Incidence of ocular neovascularization with retinal vein occlusion. 619 76


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