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Results for “RETINAL VESSELS”

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At least 253 records · Page 14Linked to original sources
PubMed1990

The fractal properties of retinal vessels: embryological and clinical implications.

The branching patterns of retinal arterial and venous systems have characteristics of a fractal, a geometrical pattern whose parts resemble the whole. Fluorescein angiogram collages were digitised and analysed, demonstrating that retinal arterial and venous patterns have fractal dimensions of 1.63 +/- 0.05 and 1.71 +/- 0.07, respectively, consistent with the 1.68 +/- 0.05 dimension of diffusion limited aggregation. This finding prompts speculation that factors controlling retinal angiogenesis may obey Laplace's equation, with fluctuations in the distribution of embryonic cell-free spaces providing the randomness needed for fractal behaviour and for the uniqueness of each individual's retinal vascular pattern. Since fractal dimensions characterise how completely vascular patterns span the retina, they can provide insight into the relationship between vascular patterns and retinal disease. Fractal geometry offers a more accurate description of ocular anatomy and pathology than classical geometry, and provides a new language for posing questions about the complex geometrical patterns that are seen in ophthalmic practice.

Computer Graphics↗
PubMed1986

Does unidirectional vesicular transport occur in retinal vessels?

This paper challenges the hypothesis that the smooth 80 nm plasmalemmal caveolae found in abundance at the abluminal aspect of the endothelium in retinal blood vessels participate in a unidirectional vesicular transport mechanism. Evidence is presented which indicates that horseradish peroxidase, when introduced to the extracellular space of the retina via the vitreous body, may enter the intravascular compartment through junctional incompetence which occurs at or after enucleation of the eye. It is proposed that the plasmalemmal caveolae at the abluminal plasma membrane of endothelial cells in retinal blood vessels are static structures which facilitate the transport of small solutes and ions across the blood retinal barrier.

Animals↗
PubMedDate not supplied

[Role of antiphospholipid antibodies in occlusion of retinal vessels in various vascular eye diseases].

A strong association between the presence of antiphospholipid antibodies (aPLab) and arterial and venous thrombosis was observed during the past decade. aPLab represent a heterogeneous group of immunoglobulins that include the lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and antibodies responsible for false-positive test for syphilis. aPLab react with negatively charged, rarely with neutral phospholipids and/or phospholipid-binding proteins. aPLab are associated with vascular occlusion in autoimmune diseases, e.g. systemic lupus erythematosus (SLE). The role of aCL in ocular vascular occlusive disease involving retinal vessels is unclear. The aim of this study was to determine the relationship between aPLab and occlusive retinal disease. A relationship between aCL (IgG), LA, and thrombotic retinal events has been detected in SLE patients, but no association between aPLab and other occlusive retinal diseases (central retinal vein thrombosis, isolated retinal vasculitis, optic nerve vasculitis). In our study the incidence of aCL IgG was higher in patients with Behcet disease with non-occlusive thrombosis than in patients with retinal occlusive events or in patients without occlusions or thrombosis. It seems that different mechanisms are responsible for these conditions.

Antibodies, Antiphospholipid↗
PubMedDate not supplied

Flat preparations of the retinal vessels in Coats' disease.

Flat preparations of the retina were prepared by trypsin digestion in ten cases of Coats' disease. All of the patients were young males with advanced disease leading to enucleation. All eyes showed marked abnormalities in the arterioles, venules, and capillaries. The findings most characteristic of Coats' disease were large aneurysms and thick PAS positive deposits in vessel walls. The aneurysms ranged from 50 to 350 microns and frequently formed large sausage-like or beaded out-pouchings and were sometimes situated on shunt vessels. Other findings frequently seen, but not specific for Coats' disease, were capillary dilatation, small aneurysms, hypocellular vessel walls, and fibrous strands.

Aneurysm↗
PubMed1983

[Aplasia of retinal vessels in congenital cytomegaly].

Case report on a premature male infant, born in the 34th week of pregnancy with bronchopulmonary dysplasia, bronchitis, hepatitis, marked cortical and subcortical atrophy of the brain with enlargement of the inner and outer subarachnoid space, with severe cerebral motility disorders and convulsions. Blood serology showed rapidly increasing cytomegaly titers, which were also elevated in the serum of the mother. The ophthalmological examination revealed a hypoplastic, white papilla in both eyes. Neither retinal arteries nor veins were seen. The macula and retinal periphery were normal. There were no signs of acute or passed retinochorioiditis. Temporary opacification of the cornea was observed. In connection with the pediatric findings the authors interpret the aplasia of the retinal vessels and the hypoplasia of the optic nerve as a result of a cytomegaly infection prior to the 4th month of pregnancy, which prevented normal development of the vessels. The temporary opacity of the cornea could be a reaction of the corneal endothelium against the virus.

Cytomegalovirus Infections↗
PubMedDate not supplied

[Results of treating thrombosis of retinal vessels in ambulatory care].

The results of therapy of retinal vascular thrombosis are analyzed. Common therapy (tissue therapy, vasodilatants, angioprotectors, group B vitamins) was supplemented after discharge from hospital (for patients with thrombosis of the central retinal vein) by laser coagulation of the retina, 10 retrobulbar injections of heparin (0.1 ml) with dexasone (0.5 ml), then 10 intravenous injections of trental (0.5 ml), 10 intravenous injections of 2.4% euphylline, and intramuscular injections of lasix (4 ml, 3 injections every other day). Immediately after discharge the patients were prescribed ethanol solution of bee glue (40 drops orally in boiled water) and 1 tea-spoon of pollen with water, both to be taken after overnight fasting. Due to intensive care, hemorrhages in the retina resolved sooner and visual acuity increased to 0.7-0.9 diopters with correction; intraocular pressure 3.4 months after the disease onset was 18.21 mm Hg. One year after the disease, patients who received no retrobulbar injections of trental, been glue, or pollen still had hemorrhages along the vessels on the fundus oculi, retinal degeneration and new vessels in the paramacular area and on the optic disk; visual acuity of these patients was 0.02 diopters without correction.

Adult↗
PubMed1995

A numeric index based on spatial frequency for the tortuosity of retinal vessels and its application to plus disease in retinopathy of prematurity.

BACKGROUND: In retinopathy of prematurity (ROP), tortuosity of vessels near the posterior pole of the fundus is an important clinical sign, yet clinicians have difficulty estimating how tortuous the vessels are. METHODS: The authors have devised an objective, numeric index of retinal blood vessel tortuosity that is especially sensitive to the structural changes in vessels that occur in ROP, but it is not particularly sensitive to non-ROP changes. Computer software is used to calculate the index from fundus images; the quality of these images is typical of photographs or video-cassette frames that the authors record in the premature nursery. RESULTS: The index reliably segregates tortuous vessels from nontortuous ones and separates eyes that reach ROP treatment threshold from eyes that do not. CONCLUSIONS: The index forms an objective measure of the ROP disease state. Its calculation requires only segments of vessels and thus, is potentially adaptable to imaging systems that automatically extract vessel portions from fundus images.

Fundus Oculi↗
PubMedDate not supplied

Filtering properties of an adaptive trend operator and the application for determining the arterial blood velocity in retinal vessels.

This study deals with methods focused on estimating blood velocity. The estimation of the linear trend function of a non-stationary signal based on the adaptive recursive estimation of the mean value function is used for the determination of the time delay of two indicator dilution curves. The filter property of this trend operator depends on the choice of a constant parameter c, the so-called adaptation factor. The functional connection between the filter property and the adaptation factor is considered in such a way that an objective calculation of arterial blood velocity in retinal vessels is possible.

Algorithms↗
PubMed2004

Indocyanine green enhanced retinal vessel laser closure in rats: histologic and immunohistochemical observations.

PURPOSE: Feeder vessel photocoagulation using both thermal and indocyanine green (ICG) enhanced applications as a treatment for choroidal neovascularization is under investigation. While closure of feeder vessels is achievable, reperfusion of these vessels occurs. The purpose of the following study was to compare, contrast anatomic, and immunohistochemical findings in rat retinal arterioles following attempts at vessel closure using either the diode (810 nm) laser alone or in conjunction with intravascular ICG. METHODS: The retinal arterioles of adult Lewis or Brown Norway rats were treated with diode laser alone or immediately following intravenous injection with 75 mg ml(-1) ICG. Retinal vessel closure was determined by examination of retinal flatmounts following FITC-dextran or rhodamine-dextran perfusion. Anatomic changes were examined by electron microscopy and quantitative cellular changes were measured by perfusion with Hoechst 33342 nuclear staining. Recruited macrophages were detected by ED1 immunohistochemistry. RESULTS: Treatment with diode laser alone resulted in partial retinal arteriolar closure seen only in pigmented animals. The use of adjuvant ICG achieved complete vessel closure in albino animals with reperfusion seen in all vessels by 7 days. Electron microscopy revealed an intraluminal clot only in ICG-enhanced diode laser treated animals, but with accompanying endothelial and perivascular cellular damage. Immunohistochemistry of the site of retinal arteriolar closure revealed a large increase in perivascular cellularity with an apparent influx of ED1 positive cells. CONCLUSION: ICG-enhanced diode laser photocoagulation appears to be superior to diode treatment alone in achieving vessel closure, but is limited by clot resolution due to both excessive vascular damage and an accompanying inflammatory response. These results suggest that more durable feeder vessel closure rates may be achievable with either the use of accompanying anti-inflammatory therapies or with a less vascular damaging photoactivating dye.

Animals↗
PubMed2005

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

Generalized retinal arteriolar narrowing is an important sign of systemic hypertension, and a lower arteriolar:venular diameter ratio predicts the risk of hypertension. We investigated whether this association was based on arteriolar or venular diameters or both. This study was based on the prospective population-based Rotterdam Study (1990-1993) and included 1900 participants (> or =55 years of age) of whom 739 persons had normal blood pressure (systolic <120 mm Hg and diastolic <80 mm Hg) and 1161 prehypertension (systolic 120 to 139 mm Hg or diastolic 80 to 89 mm Hg). For each participant, retinal arteriolar and venular diameters were measured on digitized images of 1 eye. After a mean follow-up of 6.6 years, 808 persons developed hypertension, defined as either systolic blood pressure > or =140 mm Hg or diastolic blood pressure > or =90 mm Hg or use of antihypertensive medication. Adjusted for age, gender, follow-up time, body mass index, smoking, diabetes mellitus, total and high-density lipoprotein cholesterol, C-reactive protein, and intima-media thickness, arteriolar narrowing was associated with an increased risk of hypertension (odds ratio per SD: 1.38; 95% CI, 1.23 to 1.55); for venular narrowing this was less striking (OR: 1.17; 95% CI, 1.04 to 1.32). Each SD decrease in the arteriolar:venular diameter ratio significantly increased the risk of hypertension by 24%. To examine the effect of baseline blood pressure, we stratified persons into those with "normal blood pressure" or "prehypertension." Within these strata, arteriolar narrowing was still related to incident hypertension. These data show that both retinal arteriolar and venular narrowing may precede the development of systemic hypertension.

Aged↗
PubMed1988

[Parapapillary retinal vessel caliber. II. Caliber reduction in eyes with glaucoma (a papillometric study of 309 eyes with chronic simple glaucoma compared with 264 normal eyes)].

The diameter of the temporal superior or inferior artery and vein was measured at the optic disk border and 2 mm from the disk center in 309 nonselected eyes with chronic primary open-angle glaucoma. The values obtained were compared with those of 264 nonselected normal eyes. The calibers of both vessels were significantly larger in the normal eyes than in the glaucomatous ones (p = 0.000 or p less than 0.01; Wilcoxon-Mann-Whitney test). Their diameters diminished significantly (p less than 0.001) with decreasing width and area of the neuroretinal rim as a whole and when divided into different optic disk sectors, and with increasing optic cup area, horizontal and vertical cup/disk ratios, area of the subtotal to total parapapillary choriopigmentepithelioretinal atrophy, perimetric loss, and glaucoma stage. Thus, the caliber of the parapapillary retinal vessels decreases significantly with increasing glaucomatous optic nerve damage.

Adolescent↗