Eales' disease: oxidant stress and weak antioxidant defence.
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Eales' disease (ED) is an idiopathic retinal periphlebitis characterized by capillary non-perfusion and neovascularization. In addition to the existing system, a new staging system has been proposed by Saxena et al. Immunological, molecular biological and biochemical studies have indicated the role of human leucocyte antigen, retinal S antigen autoimmunity, Mycobacterium tuberculosis genome, free radical damage and possibly hyperhomocysteinemia in its etiopathogenesis, which appears multifactorial. Oxidant stress has been shown by increase in the levels of thiobarbituric acid reactive substances (lipid oxidation) in the vitreous, erythrocytes, platelets and monocytes. A decrease in vitamins E and C both in active and healed vasculitis, superoxide dismutase, glutathione and glutathione peroxidase showed a weakened antioxidant defence. Epiretinal membrane from patients of ED who underwent surgery showed, by immunolocalization, presence of carboxy methyl lysine, an advanced glycation end product formed by glycoxidation and is involved in angiogenesis. OH. free radical accumulation in monocytes has been directly shown by electron spin resonance spectrometry. Free radical damage to DNA and of protein was shown by the accumulation of 8 hydroxy 2 deoxyguanosine (in leucocytes) and nitrotyrosine (in monocytes), respectively. Nitrosative stress was shown by increased expression of inducible nitric oxide synthase in monocytes in which levels of iron and copper were increased while those of zinc decreased. A novel 88 kDa protein was found in serum and vitreous in inflammatory condition and had antioxidant function. Platelet fluidity was also affected. Oral, methotrexate in low dosage (12.5 mg/week for 12 weeks) as well as oral vitamin E (400 IU) and C (500 mg) daily for 8 weeks are reported to have beneficial effects. (+info)
Distribution and associations of retinal vascular caliber with ethnicity, gender, and birth parameters in young children.
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PURPOSE: To describe the distribution of retinal vascular calibers and their associations with ethnicity, gender, and birth parameters in children. METHODS: This was a school-based cross-sectional study of 768 children aged 7 to 9 years who participated in the Singapore Cohort Study of the Risk Factors for Myopia (SCORM). Participants had retinal photographs taken in 2001. Retinal vascular calibers were measured with computer-based program and summarized as average caliber of arterioles and venules in that eye. Associations of retinal vascular caliber with ethnicity, gender, and various birth factors were analyzed. RESULTS: In this population, the mean retinal arteriolar caliber was 156.4 microm (95% confidence interval [CI], 155.4-157.3) and venular caliber was 225.4 microm (95% CI, 224.1-226.8). The retinal arteriolar caliber was significantly narrower in Chinese (154.9 microm), compared with Malay (158.6 microm) and Indian (158.5 microm) children. Retinal venular caliber was also narrower in Chinese (223.3 microm) compared with Malay (230.8 microm) and Indian (229.0 microm) children. These differences were statistically significant, even after adjustments for age, gender, family income, parental education, body mass index, height, birth weight, axial length, and spherical equivalent (P = 0.05 for arteriolar caliber; P = 0.002 for venular caliber). In multivariate analysis, there were no significant gender differences in retinal vascular caliber. Birth factors, including birth weight, birth length, head circumference, and gestational age, were not significantly associated with changes in either retinal arteriolar or venular caliber. CONCLUSIONS: The results show ethnic variation in retinal vascular caliber in Singaporean children. No association of birth parameters with retinal vascular caliber was found. Because retinal vascular caliber is related to various cardiovascular and ocular diseases, it is possible that ethnic variations in retinal vascular caliber should be taken into consideration in future studies. (+info)
Effects of dopamine on retinal and choroidal blood flow parameters in humans.
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AIM: To investigate the effect of dopamine on retinal and choroidal blood flow in humans. METHODS: We investigated the effect of two doses of intravenous dopamine (5 and 10 microg/kg/min) via a randomised double-masked crossover study in 12 healthy subjects chosen from a total of 16. Blood flow parameters in retina, optic nerve head and choroid were assessed with bi-directional laser Doppler velocimetry, laser Doppler flowmetry and laser interferometric measurement of fundus pulsation amplitude, respectively. RESULTS: Intravenous dopamine dose-dependently increased retinal blood cell velocity and fundus pulsation amplitude (p<0.001). At the highest administered dose red blood cell velocity in retinal vessels increased by 37% and fundus pulsation amplitude by 24%. By contrast, optic nerve head blood flow did not change with dopamine administration. CONCLUSIONS: Our data indicate that dopamine has a pronounced enhancing effect on the retinal perfusion in humans. Further studies are required to establish the exact role of dopamine in the regulation of choroidal and optic nerve head blood flow. (+info)
Total retinal volumetric blood flow rate in diabetic patients with poor glycemic control.
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Total retinal volumetric blood flow rate was measured in 12 normal subjects and 18 poorly controlled diabetic patients with background diabetic retinopathy. Maximum or center-line erythrocyte velocity (Vmax) was assessed by bidirectional laser Doppler velocimetry in four to five major retinal veins of one eye of each subject. Venous diameter (D) was measured from monochromatic fundus photographs. Total venous cross-section and measured total retinal volumetric blood flow in the diabetic patients were significantly larger than normal (P = 0.001 and P = 0.02, respectively). A positive linear correlation was found between Vmax and D in normal and diabetic eyes. Volumetric blood flow rate, Q, varied with D at a power of 2.87 in normal eyes. Total volumetric blood flow correlated with total venous cross-section. It was found that Q in the temporal retina was significantly larger than in the nasal retina in normal subjects (P = 0.0008) and diabetic patients (P = 0.0002). A significant difference in Q was observed between the superior and inferior retina in diabetic patients (P = 0.03) but not in normal subjects. The retinal vascular regulatory response to 100% oxygen breathing was reduced (P = 0.019) in diabetic patients and correlated with the level of background diabetic retinopathy. A close estimate of total volumetric blood flow may be obtained from blood flow measurement in one major retinal vein and the determination of total venous cross-section. This may be important for clinical studies in which measurements of all individual retinal veins may not be feasible. (+info)
Retinal abnormalities in early Alzheimer's disease.
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PURPOSE: There is evidence suggesting that visual disturbances in patients with Alzheimer's Disease (AD) are due to pathologic changes in the retina and optic nerve, as well as to higher cortical impairment. The purpose of this study was to evaluate retinal hemodynamic parameters and to characterize patterns of retinal nerve fiber layer (RNFL) loss in patients with early AD. METHODS: Nine patients with mild to moderate probable AD (mean Mini Mental State Examination score 24 of a possible 30 (age 74.3 +/- 3.3 years; mean +/- SD) and eight age-matched control subjects (age, 74.3 +/- 5.8 years) were included in this prospective cross-sectional study. Blood column diameter, blood velocity, and blood flow rate were measured in the major superior temporal retinal vein in each subject by using a laser Doppler instrument. Peripapillary RNFL was measured by optical coherence tomography. RESULTS: Patients with AD showed a significant narrowing of the venous blood column diameter (131.7 +/- 10.8 microm) compared with control subjects (148.3 +/- 12.7 microm, P = 0.01), and a significantly reduced venous blood flow rate (9.7 +/- 3.1 microL/min) compared with the control subjects (15.9 +/- 3.7 microL/min, P = 0.002). A significant thinning of the RNFL was found in the superior quadrant in patients with AD (92.2 +/- 21.6 microm) compared with control subjects (113.6 +/- 10.7 microm, P = 0.02). There were no significant differences in the inferior, temporal, or nasal RNFL thicknesses between the groups. CONCLUSIONS: Retinal abnormalities in early AD include a specific pattern of RNFL loss, narrow veins, and decreased retinal blood flow in these veins. The results show that AD produces quantifiable abnormalities in the retina. (+info)
New classification system-based visual outcome in Eales' disease.
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PURPOSE: A retrospective tertiary care center-based study was undertaken to evaluate the visual outcome in Eales' disease, based on a new classification system, for the first time. MATERIALS AND METHODS: One hundred and fifty-nine consecutive cases of Eales' disease were included. All the eyes were staged according to the new classification: Stage 1: periphlebitis of small (1a) and large (1b) caliber vessels with superficial retinal hemorrhages; Stage 2a: capillary non-perfusion, 2b: neovascularization elsewhere/of the disc; Stage 3a: fibrovascular proliferation, 3b: vitreous hemorrhage; Stage 4a: traction/combined rhegmatogenous retinal detachment and 4b: rubeosis iridis, neovascular glaucoma, complicated cataract and optic atrophy. Visual acuity was graded as: Grade I 20/20 or better; Grade II 20/30 to 20/40; Grade III 20/60 to 20/120 and Grade IV 20/200 or worse. All the cases were managed by medical therapy, photocoagulation and/or vitreoretinal surgery. Visual acuity was converted into decimal scale, denoting 20/20=1 and 20/800=0.01. Paired t-test / Wilcoxon signed-rank tests were used for statistical analysis. RESULTS: Vitreous hemorrhage was the commonest presenting feature (49.32%). Cases with Stages 1 to 3 and 4a and 4b achieved final visual acuity ranging from 20/15 to 20/40; 20/80 to 20/400 and 20/200 to 20/400, respectively. Statistically significant improvement in visual acuities was observed in all the stages of the disease except Stages 1a and 4b. CONCLUSION: Significant improvement in visual acuities was observed in the majority of stages of Eales' disease following treatment. This study adds further to the little available evidences of treatment effects in literature and may have effect on patient care and health policy in Eales' disease. (+info)
Relationship of retinal vascular caliber with optic disc diameter in children.
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PURPOSE: To describe the relationships of retinal vascular caliber to optic disc diameter in children. METHODS: A school-based cross-sectional study of 746 children aged 7 to 9 years who participated in the Singapore Cohort Study of the Risk Factors for Myopia. Digital retinal photographs of both eyes were taken in 2001 and graded for retinal vascular caliber, vertical optic disc diameter, and vertical cup-to-disc ratio (CDR) according to standardized protocols. All measurements in pixels were analyzed after correction of the magnification. RESULTS: In this study population, the mean retinal arteriolar caliber (SD) was 5.95 (0.51) pixels, retinal venular caliber was 8.58 (0.69) pixels, vertical disc diameter was 73.02 (7.48) pixels, and vertical CDR was 0.34 (0.09). In multiple linear regression analysis with adjustment for age, gender, ethnicity, body mass index, and birth weight, arteriolar caliber decreased by 0.011 pixel (P < 0.001) and venular caliber decreased by 0.016 pixel (P < 0.001), for each pixel decrease in vertical optic disc diameter. The associations remained similar and statistically significant with further adjustment for blood pressure. Vertical CDR was not related to retinal vascular caliber. CONCLUSIONS: In this population of generally healthy children, smaller vertical optic disc diameter was associated with narrower retinal arteriolar and venular calibers. The findings of this study, in conjunction with studies in adults, suggest anatomic relationships between the optic disc and retinal vasculature that may provide additional insights into the vascular etiology of glaucomatous and nonarteritic anterior ischemic optic neuropathy. However, because the detected differences in retinal vascular caliber were small, the clinical significance of the study findings remains uncertain. (+info)
Dietary fiber intake and retinal vascular caliber in the Atherosclerosis Risk in Communities Study.
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BACKGROUND: Dietary fiber appears to decrease the risk of cardiovascular morbidity and mortality. Microvascular abnormalities can be observed by retinal examination and contribute to the pathogenesis of various cardiovascular diseases. The impact of dietary fiber on the retinal microvasculature is not known. OBJECTIVE: We aimed to examine the association between dietary fiber intake and retinal vascular caliber. DESIGN: At the third visit (1993-1995) of the Atherosclerosis Risk in Communities (ARIC) Study, a population-based cohort of adults in 4 US communities, the retinal vascular caliber of 10,659 participants was measured and summarized from digital retinal photographs. Usual dietary intake during the same period was assessed with a 66-item food-frequency questionnaire. RESULTS: After control for potential confounders including hypertension, diabetes, lipids, demographic factors, cigarette smoking, total energy intake, micronutrients intake, and other cardiovascular disease risk factors, higher intake of fiber from all sources and from cereal were significantly associated with wider retinal arteriolar caliber and narrower venular caliber. Participants in the highest quintile of fiber intake from all sources had a 1.05-microm larger arteriolar caliber (P for trend = 0.012) and a 1.11-microm smaller venular caliber (P for trend = 0.029). CONCLUSIONS: Dietary fiber was related to wider retinal arteriolar caliber and narrower venular caliber, which are associated with a lower risk of cardiovascular disease. These data add to the growing evidence of the benefits of fiber intake on various aspects of cardiovascular pathogenesis. (+info)