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PubMed2004

Familial aggregation of retinal vessel caliber in the beaver dam eye study.

PURPOSE: To describe familial correlations of retinal vessel measurements. METHODS: A standardized examination and interview was administered to a population-based cohort of adults aged 43-86 years. Blood pressure was measured, and family relationships, current smoking status, and photographs of the retina were obtained. Computer-assisted grading was done to determine central retinal arteriole (CRAE) and venule equivalents (CRVE), and the arteriole-to-venule ratio (AVR) was computed. Familial correlations were calculated using FCOR in the SAGE software package. Analysis was done on the right eye measures for 871 sibling, 341 parent-child, 1362 cousin, 554 avuncular, and 887 spousal pairs. RESULTS: After adjustment for age, gender, mean arterial blood pressure, and current smoking status, the correlations (and 95% confidence interval) between siblings for the CRVE, CRAE, and AVR were 0.23 (0.16, 0.31), 0.20 (0.12, 0.28) and 0.13 (0.05, 0.20), respectively. Parent-child correlations were very similar, and the avuncular correlations were about half as great. The cousin correlations were about half the avuncular correlations. Spousal correlations of 0.03, 0.04, and 0.01 for CRVE, CRAE, and AVR, respectively, were not significantly different from 0. CONCLUSIONS: Retinal vessel equivalents were more highly correlated between relatives than between unrelated individuals. The relative magnitudes of these correlations were likely the result of shared genes. Because the vessel measurements have been shown to be predictive of cardiovascular and other systemic diseases, understanding the determinants of these familial relationships could have important health benefits.

Adult↗

PubMed2001

Light paths in retinal vessel oxymetry.

The oxygen utilization and, therefore, the metabolic state, of a distinctive area of the retina may be calculated from the diameter of the supplying artery and vein, the haemoglobin oxygenation, and the velocity of the blood. The first two parameters can be determined by imaging spectrometry at the patients ocular fundus. However, the reflected light emerging from a vessel followed different pathways through the ocular fundus layers and the vessel embedded in the retina. The contribution of the single pathways to the vessel reflection profile is investigated by a Monte Carlo simulation. Considering retinal vessels with diameters of 25-200 microm we found the reflection from a thin vessel to be determined by the single and double transmission of light at 560 nm. The backscattering from the blood column determines the reflectance in the case of a thick vessel. However, both components are in the same order of magnitude. This has to be considered in the calculation of the oxygen saturation of blood in retinal vessels from their reflection spectra.

Light↗

PubMed1994

Changes in the retinal pigment epithelium close to retinal vessels in familial adenomatous polyposis.

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is known to occur in patients with familial adenomatous polyposis. Its relation to the course of the retinal blood vessels is emphasized in this publication. A 15-year-old girl with familial polyposis coli showed a longitudinal strip of whitish change following the course of a superior nasal artery of the left eye, falsely appearing to enclose the blood vessel like a sheath. A 34-year-old woman from another family with polyposis coli also showed a longitudinally orientated area of hypo- and hyperpigmentation close to temporal retinal veins. Two further patients revealed hyperpigmentation of the RPE under retinal vessels. It is hypothesized that these changes indicate an effect of the hypo- and hyperpigmentations of the RPE on the development of retinal vessels. In four patients, multiple dotlike hyperpigmentations were found in the extreme periphery of the retina; however, the bigger patchy hyperpigmentations were predominantly located in the midperiphery of the retina.

Adenomatous Polyposis Coli↗

PubMed1991

Increased immunoreactivity of collagen types I, III and V, fibronectin and TGF-beta in retinal vessels of rats with experimental autoimmune uveoretinitis.

The immunoreactivity of types I, III and V collagen, fibronectin and transforming growth factor-beta (TGF-beta) was studied by an immunogold labeling method in retinal vessels of rats with experimental autoimmune uveoretinitis (EAU) induced by retinal S-antigen. The basal lamina of retinal capillaries in normal rats showed low immunoreactivities for the extracellular matrix components and TGF-beta. However, at the peak of inflammation (day 13-16 postimmunization), labeling of all three types of collagen and fibronectin increased considerably in the basal lamina of retinal vessels. TGF-beta immunoreactivity was detected mainly in the vascular endothelium and the pericytes. The results suggest that TGF-beta synthesized by the endothelial cells and pericytes may regulate the synthesis and composition of extracellular matrix components in the vascular basal lamina during the course of EAU development.

Animals↗

PubMed2006

Retinal vessel diameters and risk of stroke: the Rotterdam Study.

BACKGROUND: Retinal vessels may provide information on cerebral vascular pathology, because they share many features with cerebral vessels. A smaller ratio of the retinal arteriolar-to-venular diameters reportedly predicts the risk of stroke. It is unclear if this is due to arteriolar narrowing or venular dilation. OBJECTIVE: To investigate whether smaller arteriolar or larger venular diameters are related to the risk of stroke and cerebral infarction. METHODS: This study was based on the prospective population-based Rotterdam Study and included 5,540 participants of 55 years or over, who had gradable fundus transparencies and were free of stroke at baseline (1990 to 1993). For each participant, retinal arteriolar and venular diameters were measured on digitized images of one eye. Follow-up for first-ever stroke was complete until January 1, 2002. RESULTS: After a mean follow-up of 8.5 years, 411 participants had a stroke, of whom 259 had cerebral infarction. Larger venular diameters were associated with an increased risk of stroke (hazard ratio [HR] adjusted for age and sex per SD increase: 1.12 [95% CI: 1.02 to 1.24]) and cerebral infarction (HR: 1.15 [95% CI: 1.02 to 1.29]). Smaller arteriolar diameters were neither related to the risk of stroke (HR per SD decrease: 1.02 [95% CI: 0.93 to 1.13]) nor to the risk of cerebral infarction (HR: 1.02 [95% CI: 0.90 to 1.15]). After additional adjustment for other cardiovascular risk factors, the results did not change. CONCLUSIONS: Larger retinal venular diameters are associated with an increased risk of stroke and cerebral infarction. The role of venules in cerebrovascular disease warrants further exploration.

Age Factors↗

PubMed2002

Corkscrew retinal vessels in neurofibromatosis type 1: report of 12 cases.

AIM: To describe a distinctive spectrum of retinal microvascular abnormalities in 12 patients with neurofibromatosis type 1 (NF-1). METHODS: This is an observational prospective study of the ocular fundus evaluated by direct ophthalmoscopy with or without fluorescein angiography, to investigate retinal microvascular abnormalities in 32 patients with NF-1 and in 30 control subjects. The evaluation included a complete general and neurological physical examination and in some cases computed tomography, magnetic resonance imaging with gadolinium-DTPA, or both. RESULTS: The occurrence of a distinctive spectrum of retinal microvascular abnormalities is described in 12 patients with NF-1 (37.5%). At the lower end of the spectrum, present in 10 patients, the anomaly consisted of minuscule second or third order tortuous venules, which were called "corkscrew retinal vessels." These were usually isolated but in a few cases multiple. They flow towards the superior or inferior temporal veins. They had a length of one to two disc diameters. They ended either in a minute tuft or vanished on the retinal surface. The upper end of the spectrum was seen in only two patients. One of them had an exceptionally large venous anastomosis on the nasal retina and the other had an arteriovenous malformation extending over one retinal quadrant. None of the patients in the control group had such retinal microvascular abnormalities. CONCLUSION: The "corkscrew" retinal vessels described in this report constitute a broad spectrum of microvascular markers in NF-1 patients.

Adolescent↗

PubMed1988

The calibre changes of retinal vessels subject to prolonged hyperoxia.

The constriction of retinal vessels occurring in response to breathing 100% oxygen was studied in 10 normal subjects over a period of 30 min. Brachial blood pressure, radial pulse and end tidal CO2 were recorded throughout. The mean arteriolar constriction was 15.3% +/- 4.6 and venous constriction 21.8% +/- 4.3. Time constants (the time for 95% of the maximal response to have occurred) were 2.25 min +/- 0.75 and 2.37 min +/- 0.57 for arterioles and veins respectively. A highly variable late vascular response was recorded. A small proportion of arterial vessels showing a response were nonuniform while a larger proportion of veins showed a significant dilatation.

Adult↗

PubMed1992

Retinal vessel autoregulation in sickle cell patients.

We tested retinal vessel autoregulation in 16 sickle cell patients and 6 controls by computer-assisted measurements of constriction of the superior and inferior temporal veins and arteries after pure oxygen breathing. Compared to the controls and corrected for age, we found a decrease of vasoconstriction in three of the four vessels measured in the sickle cell group, which was statistically significant only for the superior temporal artery (P 0.009). The number of patients was too small to allow a separate analysis of possible contributory factors within the sickle cell group, such as sickle cell hemoglobin subtype and extent of retinal ischemia. Our findings indicate a factor not yet well known in the pathophysiology of sickle cell disease: an abnormality of local microvascular control.

Adult↗

PubMed1983

Unidirectional vesicular transport mechanism in retinal vessels.

When horseradish peroxidase (HRP) is introduced into the bloodstream, it is retained in the lumen of the retinal vessels (blood-retina barrier). In this paper, we report that when the same tracer is injected into the vitreous body, it penetrates the lumen of retinal vessels by transcellular vesicular transport. This unidirectional movement of macromolecules out of the eye is not inhibited by ouabain, fluoroacetate, or low temperatures.

Animals↗

PubMed1979

[The passage of dyes through the retinal vessels].

Examinations of the retinal haemodynamics after injection of fluorescein sodium were performed on three groups of test persons, in normal persons, patients with diseases of the retina as well as patients with organic heart defects. In the group of heart diseases statistically significant disturbances of the retinal haemodynamics could be proved, which the retina tolerates without any lesion. In comparison to this retinopathies with severe changes of the fundus show only slight disturbances of the haemodynamics. These do not give the possibility of the explanation of the changes of the fundus.

Adult↗

PubMed1990

Abnormally distributed branches of the retinal vessels, enlarged macular arteries and long cilioretinal arteries.

We examined fundus photographs of 3,506 eyes and noted uncommon retinal vessel patterns in the temporal quadrants of the posterior fundus. Of 1,753 subjects, 20 patients (21 eyes) had unusual retinal vessel patterns. Seven eyes had an abnormally distributed branch of the inferotemporal artery; 8 eyes had an enlarged macular artery. Of these 20 patients, 1 had visual complaints associated with the unusual vascular patterns.

Adult↗

PubMed2004

Carbonic anhydrase inhibition increases retinal oxygen tension and dilates retinal vessels.

BACKGROUND: Carbonic anhydrase inhibitors (CAIs) increase blood flow in the brain and probably also in the optic nerve and retina. Additionally they elevate the oxygen tension in the optic nerve in the pig. We propose that they also raise the oxygen tension in the retina. We studied the oxygen tension in the pig retina and optic nerve before and after dorzolamide injection. Also the retinal vessel diameters during carbonic anhydrase inhibition were studied. METHODS: A polarographic oxygen electrode was placed transvitreally immediately over the retina or the optic disc in anaesthetised pigs. The oxygen tension was recorded continually and 500 mg dorzolamide was injected intravenously. Retinal vessel diameters were analysed from monochromatic fundus photographs taken before and after injection of dorzolamide. RESULTS: Baseline retinal oxygen tension (RPO2) was 3.34+/-0.50 kPa (mean +/- SD, n=6) and baseline optic nerve oxygen tension (ONPO2) was 3.63+/-1.00 kPa. RPO2 was increased by 0.36+/-0.11 kPa (n=6, P=0.025) and ONPO2 by 0.73+/-0.34 kPa (n=6, P=0.003) 30 min after dorzolamide administration. The retinal arterioles was significantly dilated by 13+/-7% (n=5, P=0.016) and the retinal venules by 12+/-8% (n=5, P=0.030) 30 min after injection of dorzolamide. CONCLUSION: Retinal and optic nerve oxygen tension increased with systemic administration of dorzolamide. The retinal vessels dilated, probably causing increased blood flow inducing the observed increase in RPO2. The increased oxygenation of retina by CAI may offer therapeutic possibilities in ischaemic diseases of the retina and optic nerve.

Animals↗

PubMed2003

Hypertensive retinal vessel wall signs in a general older population: the Blue Mountains Eye Study.

To describe cross-sectional relations between hypertension and retinal vessel wall signs in an older white population. These signs were defined from fundus photographs in 3654 Blue Mountains Eye Study participants > or =49 years of age. Focal arteriolar narrowing and arteriovenous nicking were graded through the use of standard protocol. Photographs were digitized to measure retinal vessel diameters. Average arteriolar diameter, summarized as central retinal arteriolar equivalent and arteriole-to-venule ratio, were used as indexes of generalized arteriolar narrowing. Blood pressure was measured with the use of a mercury sphygmomanometer. Hypertension was defined through the use of antihypertensive medications, systolic blood pressure > or =160 mm Hg, or diastolic blood pressure > or =95 mm Hg. Hypertension was categorized as controlled (using medication, normal blood pressure), uncontrolled (using medication, high blood pressure), or untreated (not using medication). Hypertensive subjects had higher prevalence of all retinal microvascular signs. After adjusting for age, gender, body mass index, and smoking, persons with controlled (18.2%), uncontrolled (13.8%), or untreated hypertension (13.8%) were significantly more likely than normotensive subjects (54.2%) to have (a) lower central retinal arteriolar equivalent: adjusted odds ratios 1.5, (95% CI, 1.1 to 1.9), 2.1 (1.6 to 2.7), and 2.1 (1.6 to 2.7), respectively, and lower arteriole-to-venule ratio: 1.3 (1.0 to 1.6), 1.4 (1.1 to 1.8), and 1.7 (1.3 to 2.2), respectively; (b) focal arteriolar narrowing: 1.3 (0.9 to 1.9), 2.2 (1.5 to 3.2), and 2.5 (1.8 to 3.6), respectively; and (c) arteriovenous nicking: 1.3 (0.9 to 1.8), 2.3 (1.6 to 3.2), and 1.9 (1.3 to 2.7), respectively. Our findings demonstrate a strong relation between presence and severity of hypertension and retinal microvascular structural changes.

Aged↗

PubMed2003

Computer-assisted retinal vessel measurement in an older population: correlation between right and left eyes.

This study assessed the correlation between computer-assisted retinal vessel measurements of right and left eyes, from subjects in a defined, community-based older population. Retinal photographs from participants in the Blue Mountains Eye Study were digitized. All retinal arterioles and venules located 0.5-1.0 disc diameters from the optic disc margin were identified and a computer program measured their diameters. Pearson correlation (R2) statistic was used to assess the correlation in a random subsample of 1546 images. Substantial correlation between right and left eye measurements was found for summary indices of retinal arterioles (R2 = 0.70) and venules (R2 = 0.77). Higher correlation was found for intragrader (R2 0.75-079) than for intergrader assessment (R2 0.67-0.72). Moderate correlation was found in arteriole-to-venule ratio assessed by the same (R2 = 0.57) or different (R2 = 0.52) graders. Measurements from one eye can thus adequately represent the retinal vessel diameters of a person.

Aged↗

PubMed1975

Coagulation and platelet adhesion-inducing factor in the endothelium of the retinal vessels.

By means of an immunofluorescent technique, we found factors promoting blood coagulation and platelet adhesion in the intima of retinal vessels. These factors coexisted with other agents causing the opposite process, fibrin dissolution. The components of this vascular hemostatic balance are possibly involved in the thrombotic occlusion of the retinal vessels, their canalization, and in the pathogenesis of diabetic retinopathy.

Animals↗

PubMed1979

Retinal vessels: proliferation of endothelium in vitro.

Tissue culture of retinal vessels from fetal calf eyes produced colonies of endothelium, pericytes, and smooth muscle. Identification of endothelial cells was based upon culture morphology, [3H]thymidine labeling of isolated vessels, and factor VIII immunofluorescence. Thimerosal added to the culture medium destroyed pericytes and muscle cells, leaving only endothelial cell colonies in the primary cultures. This tissue culture system may be useful in the study of retinal vascular cell biochemistry and pathophysiology.

Animals↗

PubMedDate not supplied

[Photocoagulation in selected cases of pathology of retinal vessels].

The authors presented methods and results of treatment by means of an argon laser of 12 patients with pathological changes of the retinal vessels. Diagnosed in these patients were: capillary haemangioma (Hippel-Lindau disease), teleangiectasis and macroaneurysms of the retinal vessels. Photocoagulation by argon laser of these vascular changes in these patients in right time showed to be a favourable therapeutic method, especially when the changes are localized in the posterior pole of the eye.

Adult↗

PubMed2002

[Reproducibility of measurements with the retinal vessel analyzer under optimal conditions].

BACKGROUND: [corrected] To evaluate the reproducibility of measurements with the Retinal Vessel Analyzer (RVA) in healthy subjects and to describe which measuring conditions should be guaranteed to obtain optimal results. METHODS: The diameter of retinal arteries and veins of 20 healthy subjects (M : F = 11 : 9; mean age: 33 +/- 12 years) were measured with the RVA at baseline, after 2 hours, and after 2 weeks. RESULTS: No statistically significant differences in the diameter of retinal arteries and veins between the single measurements were present. Short-term variability of arterial diameter was 1 %, and the intraclass correlation coefficient kappa was 0.96. Long-term variability was 1.8 %, kappa was 0.98. In retinal veins, a short-term variability of 1 % was calculated, with a kappa of 0.97. Long-term variability was 1.5 %, with a kappa of 0.98. CONCLUSION: Due to the high reproducibility of its measurements, the RVA appears to be a useful device for both analysis and follow-up of retinal vessel diameters.

Adult↗