Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RETINAL VESSELS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed1993

[Endothelin-1-induced vasoconstriction in retinal blood vessels in the rabbit].

Endothelin-1 (ET-1) is an endothelium-derived potent vasoconstrictor peptide which is synthesized in retinal vessels. In order to investigate its effect on retinal blood vessels, we injected ET-1 intravitreally (10(-12), 3 x 10(-12), 10(-11), 3 x 10(-11), 10(-10) mole) and examined the change in diameters of retinal arteries in rabbits by fundus photography. After injection of a high dose (10(-10) mole) of ET-1, fluorescein angiography was used to investigate whether complete occlusions of retinal blood vessels occurred or not. 3 x 10(-12) mole ET-1 induced contraction of retinal arteries and the contraction of those induced by 10(-10) mole ET-1 showed complete occlusion. A medium dose (10(-11) mole) of ET-1 caused repeated vasospasms and segmental vasoconstrictions of retinal blood vessels. Fluorescein angiograms revealed that retinal blood flow was interrupted transiently by injection of a high dose (10(-10) mole) of ET-1. These findings suggested that intravitreal injection of ET-1 could provide a new model of experimental transient occlusion of retinal vessels in rabbits.

Animals↗
PubMed1977

[Collateral circulations and new vessels in retinal branch vein occlusions. II. New vessels (author's transl)].

Two types of anastomotic new vessels develop after retinal branch vein occlusions. In a previous article (Arch. Ophtal. (Paris), 1977, 8-9, pp. 507-522) the useful collateral vessels were described in the re-establishment of a better circulation in the territory of the occluded vein. The second part discusses new vessels: they are dangerous and useless. Their pathogenesis poses the problem of the relationship between hypoxia, ischaemia, revascularisation and vasoproliferation. Their prevention and treatment calls for laser photocoagulation of the ischaemic territory.

Argon↗
PubMed2003

Arteriovenous crossing dissection without separation of the retina vessels for treatment of branch retinal vein occlusion.

PURPOSE: To evaluate visual outcome after arteriovenous (AV) crossing dissection for the treatment of branch retinal vein occlusion (BRVO) and secondary macular dysfunction in which difficulty separating the retinal vessels was experienced. METHODS: A pars plana vitrectomy and dissection of the involved AV crossing site were performed consecutively in 20 eyes of 20 patients with BRVO and vision loss. The overlying retinal artery was dissected free from the retinal surface, and separation of the artery and vein at the crossing site was attempted. RESULTS: In 19 of 20 eyes, the retinal artery was dissected around the crossing site, but a marked adhesion between the artery and vein precluded separation. After a mean follow-up of 10.5 months, VA improved by at least two lines in 16 eyes (80%), remained unchanged in three eyes (10%), and worsened by at least two lines in three eyes (10%). Mean change (+/- SE) in logMAR acuity was -0.28 +/- 0.11 (two or three lines of improvement, P = 0.016) at 1 to 2 months' follow-up and -0.44 +/- 0.14 (three or four lines of improvement, P = 0.008) at the final follow-up. Cataract formation or progression occurred in 88%. CONCLUSIONS: A surgically important adhesion between the retinal artery and vein at proximal AV crossings was encountered in all eyes undergoing AV crossing dissection, correlating with previous histologic and cadaver eye studies. Cataract formation or worsening was a frequent complication. Visual improvement may occur after vitrectomy and AV crossing dissection without separation of the retinal vessels.

Adult↗
PubMed2000

Ocular changes in heredo-oto-ophthalmo-encephalopathy.

BACKGROUND: Heredo-oto-ophthalmo-encephalopathy (HOOE) is a dominantly inherited disease characterised by gradual loss of vision from the age of 20, progressive hearing loss from the late 20s, cerebellar ataxia in the 30s, and death in dementia in the fourth or fifth decade. Currently, no detailed description has been given of the ocular changes seen in HOOE. Therefore, the ocular changes of HOOE were described on the basis of clinical and histological data from six affected family members. METHODS: Three members of the family affected by HOOE were subjected to a full ophthalmological re-examination, and postmortem examination was done on three eyes from two affected family members. RESULTS: Visual loss in HOOE was caused by posterior subcapsular cataract and retinal neovascularizations leading to vitreous haemorrhages and neovascular glaucoma. In the retina there was extensive accumulation of an amyloid material, both diffusely and in the walls of the retinal vessels. The retinal glial cells showed extensive pathological changes and retinal Müller cells were seen to occlude the lumen of retinal vessels. CONCLUSION: Heredo-oto-ophthalmo-encephalopathy is a familial amyloidosis of the central nervous system which is different from previously reported cases of amyloidosis by including cataract and retinal neovascularizations. The disease is accompanied by extensive changes in retinal glial cells that may play a part in the pathophysiology of the ocular complications of the disease.

Cerebellar Ataxia↗
PubMed2000

The cortical representation of shadows cast by retinal blood vessels.

PURPOSE: We inquired whether the representation of angioscotomas could be detected in the primary (striate) visual cortex. METHODS: In 12 normal squirrel monkeys, the ocular fundi were photographed and retinal vascular landmarks were projected onto a tangent screen for calibration. Each animal then underwent monocular enucleation under general anesthesia. Animals were perfused after 8 to 10 days, and flat-mounted sections of striate cortex were processed for the metabolic enzyme cytochrome oxidase (CO). RESULTS: In each animal, the cortical region corresponding to the blind spot appeared as a 3 x 2 mm oval in the CO staining pattern. It stood out because it received input from only 1 eye. In 9 of 12 animals, the representation of the major retinal vessels was also visible, for the same reason. In our best examples, CO sections showed about 10 thin lines radiating from the blind spot representation. Some could be traced for 15 mm, all the way to the vertical meridian. Vessels only 12 minutes of arc in diameter were represented in the cortex. Each angioscotoma representation in the cortex could be matched with its corresponding retinal vessel in the fundus. CONCLUSIONS: Our findings show that (1) the visual field map in layer IVc is more precise than indicated by physiological studies, and (2) visual experience must refine the final pattern of geniculocortical projections, given that the retinal vessels can produce a shadow only after birth.

Animals↗
PubMed1988

Beta 1 and beta 2 adrenergic binding sites in bovine retina and retinal blood vessels.

To supplement previous demonstration of angiotensin II and alpha-adrenergic binding sites, beta-adrenergic binding sites for dihydroalprenolol were demonstrated in vessel-free bovine neural retina (Kd = 2.5 nM) and bovine retinal vessels (Kd = 2.8 nM). By means of competition of 3H-dihydroalprenolol with betaxolol and ICI 118,551, approximately equal proportions of Beta 1 and Beta 2 subtypes were found in both the retinal vessels and the neural retina. Further studies are needed to determine the microanatomic location of the binding sites and the physiologic responses, if any, they mediate.

Animals↗
PubMed2006

Fluorescein angiographic features of the congenital hypertrophy of the retinal pigment epithelium in the familial adenomatous polyposis.

PURPOSE: To asses the prevalence of fluorescein angiographic features in bilateral and multifocal Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) in patients with a diagnosis of familial adenomatous polyposis. METHODS: We performed prospective angiographic and clinical examination of 49 CHPRE lesions in 15 patients. RESULTS: About 77.5% of CHRPE lesions were close to retinal vessels. The retinal vascular changes observed overlying and surrounding the CHRPE were: capillary non-perfusion with an area greater than 0.5 disc diameters (41%), capillary microaneurysms (4%), chorioretinal anastomoses (6.2%), attenuation of retinal vessels (4%), choriocapillary vessels inside the lacunae (6.2%) and in the depigmented marginal halo (18.4%). Depigmented streaks in contact with one or both edges of the CHRPE were observed in 79.6% of the lesions. About 9.6% of the lesions were not seen on ophthalmoscopy and could only be detected by angiography. CONCLUSIONS: Even though the diagnosis of CHRPE is clinical, fluorescein angiography may be useful in confirming the diagnosis, as well as detecting additional lesions not seen by means of ophthalmoscopic examination.

Adenomatous Polyposis Coli↗
PubMed1976

Fluorescein angiography of the normal and diseased ocular fundi of the laboratory dog.

A method was determined for fluorescein angiography of the ocular fundus of the laboratory Beagle, using a portable fluorescein fundus camera. A 10% solution of sodium fluorescein was injected by a syringe pump in the right cephalic vein of each dog. Acepromazine maleate (0.5 mg/kg, IV) with ketamine hydrochloride (10 mg/kg, IM) provided chemical restraint. Of the 10-, 25-, and 50-mg/kg dosages of fluorescein, 25 mg/kg permitted satisfactory fluorescence of the choroidal and retinal vasculature and the recirculation phase. High-speed color film permitted good quality photography of the tapetal and nontapetal retinal vessels. Reduced retinal blood vessel and pigment epithelium permeability was demonstrated by fluorescein angiography in dogs with chorioretinitis associated with systemic blastomycosis, retinitis associated with distemper, serous retinal detachment, and preretinal hemorrhage.

Animals↗
PubMed2003

Effects of sildenafil on retinal blood flow and flicker-induced retinal vasodilatation in healthy subjects.

PURPOSE: Sildenafil is a specific inhibitor of phosphodiesterase V, which is widely used for the treatment of erectile dysfunction. Sildenafil has been shown to induce vasodilation in several vascular beds by inhibiting the cGMP breakdown. The present study was conducted to investigate whether sildenafil increases blood flow in the human retina. METHODS: In a randomized, double-masked, placebo-controlled, two-way crossover study in 12 healthy male volunteers the effects of a single dose of 100 mg sildenafil were studied. Subjects received sildenafil or placebo on two different study days. After administration, retinal hemodynamic parameters were measured every 20 minutes. Retinal vessel diameters and retinal blood velocity were assessed with the retinal vessel analyzer and bidirectional laser Doppler flowmetry, respectively. In addition, the response of retinal vessel diameters to stimulation with diffuse flicker light was studied. Blood pressure and intraocular pressure were measured with noninvasive techniques. RESULTS: Sildenafil had no effect on mean arterial pressure, pulse rate, intraocular pressure, retinal blood velocity, or retinal arterial diameter. However, a significant increase in retinal venous diameters (4.7% +/- 3.2%; P=0.0028 versus placebo) and retinal blood flow 15.7% +/- 18.0%; P=0.029 versus placebo) was observed. Sildenafil had no effect on flicker-induced vasodilation in retinal arteries or veins. CONCLUSIONS: The data indicate that sildenafil increases retinal venous diameters and retinal blood flow in healthy subjects. By contrast, it does not affect intraocular pressure and flicker-induced retinal vasodilation. Further studies are needed to elucidate whether this drug may be therapeutically used in retinal ischemic disease.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1977

Permeability and patency of retinal blood vessels in experimental diabetes.

Increased permeability of retinal blood vessels in human diabetic retinopathy is well known clinically. Its morphologic equivalent is unknown. In dogs with 5 years of poorly controlled alloxan diabetes and nonproliferative diabetic retinopathy comparable to that of man, permeability and patency of retinal blood vessels were tested with the protein tracer horseradish peroxidase and evaluated by electron microscopy. A breakdown of the blood-retinal barrier was found associated with extensive tracer leakage around retinal blood vessels. Tracer had seemingly permeated endothial junctions, and was not transported through the endothelial cytoplasm. Blood vessels which had lost their endothelial cells and were partially occluded by glial cells retained some patency to tracer. These findings suggest the following. (1) Endothelial tight junctions are not a static cell specialization but one that can open due to chronic metabolic or osmotic factors prevailing in diabetes. Opened tight junctions may account for plasma leakage seen clinically in human diabetic retinopathy. (2) In the absence of endothelial cells perfusion does not necessarily end abruptly. The tracer method and electron microscopy may show details of vascular obstruction that are not readily demonstrated clinically.

Animals↗
PubMed1990

Radiation-induced ocular injury in the dog: a histological study.

Radiation-induced ocular injury secondary to treatment of nasal cancer occurs in humans and animals. Dogs with nasal carcinomas were randomized to receive 36 to 67.5 Gy in fractionated doses given in 4 weeks using a 6 MV linear accelerator. Ophthalmic examinations were performed according to a predetermined protocol and eyes were removed for histologic examination when dogs were euthanatized. The eye in the radiation field exhibited greater injury than the contralateral eye with nasal areas of the globe having more severe lesions than temporal areas. Lesions occurred in all dogs and at all doses. At 1 month or less postirradiation treatment, all dogs had blepharitis, keratoconjunctivitis and corneal epithelial atrophy. Surface lesions persisted in all eyes, becoming less severe and more chronic with time. At 3-6 months postirradiation treatment, degenerative angiopathy of retinal vessels appeared with multifocal retinal hemorrhage and mild diffuse retinal degeneration which affected outer layers first and progressed inwardly with time. At 6 months postirradiation treatment, there were cataracts, fibrosis of retinal vessel walls with loss of vascular smooth muscle, retinal hemorrhage, and mild to moderate retinal degeneration. At 1 year postirradiation treatment, retinal vessels remained sclerotic, retinal hemorrhage was less frequent, and there was moderate retinal degeneration with swelling and loss of ganglion cells. By 2 years or more postirradiation treatment, optic nerve axonal degeneration secondary to retinal changes had appeared. Tapetal and choroidal atrophy were inconsistently seen. Thus, ocular lesions at the doses received developed along a relatively predictable time course and recovery was not seen. Structures of the canine eye appear sufficiently sensitive that even relatively low total doses given in small doses per fraction cause significant long-term injury.

Animals↗
PubMed1994

[Retinal blood vessel measurement using a line sensor].

Retinal blood vessel diameters were measured with a line sensor and a fundus camera. The measurement time was 1.0 second and the measured value was determined in about 0.1 second. The measured values were compared with those obtained by measuring fundus photographs under a microscope. Opaque lines on a film were used as model vessels and the widths of the lines were measured. The reproducibility was 0.196 +/- 0.253 (mean +/- standard deviation)% and significantly better than that of the microscopic method (0.563 +/- 0.321%). The correlation between the measured values and the actual values which were obtained by directly measuring the film with a microscope was 0.999. The diameters of 17 retinal arteries (diameter 43.3-109. 4 microns) and 196 retinal veins (diameter 35.6-193.2 microns) from 35 eyes of 20 normal volunteers were measured. The reproducibility was 1.72 +/- 1.93% in retinal arteries and 2.11 +/- 2.79% in veins, which tended to be smaller than in the microscope method. The correlation between the values obtained by the line sensor method and those measured by microscope was 0.797 in retinal arteries and 0.915 in veins.

Adult↗
PubMed1989

Biochemical evidence for cholinergic activity in retinal blood vessels.

Blood vessels from human, cat, pig and bovine retinas were analyzed for their contents of choline acetyltransferase (ChAT) and muscarinic binding sites. ChAT was measured by the synthesis of 3H-acetylcholine in the presence of 3H-acetyl CoA and choline. Muscarinic binding sites were determined by the specific binding of 3H-quinuclidinyl benzylate (3H-QNB). Tissue levels of ChAT varied from 39-850 nmol/g/hr, the lowest values being in human tissues. Muscarinic binding sites were less different (0.5 to 1.8 fmol/mg net weight) among the species studied, being the highest values in human retinal vessels. It appears that retinal blood vessels not only have sites to bind acetylcholine, perhaps to mediate physiologic responses, but might be capable of supplying acetylcholine for local vascular tone control.

Animals↗