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At least 217 records · Page 12Linked to original sources
PubMed1977

Electron-microscopic histochemistry of the most peripheral retinal vessels.

The reaction of Thiéry (periodic acid-thiocarbohydrazide-silver proteinate) has been applied for histochemical analysis of the structures composing the halo of the most peripheral human retinal vessels. It is suggested that glycoproteins lie in the ground substance of the halo as well as well as in the basement membranes of endothelial cells, pericytes, and Müller cells. Glycogen particles were found in endothelial cells, in pericytes and especially in Müller cells.

Basement Membrane↗
PubMed1998

Retinal vessel diameter in normal and primary open-angle glaucoma.

The purpose of this study was to determine how closely peripapillary retinal vessel diameter is related to functional and structural optic nerve damage in primary open-angle glaucoma. Using optic disc photographs of 234 eyes of 141 patients with primary open-angle glaucoma and 139 eyes of 86 normal subjects, the diameters of the superior and inferior temporal retinal arteries and veins were measured at the optic disc border. On the basis of rim/disc area ratio, the glaucoma group was divided into four stages: early, more than 0.61; medium, 0.60-0.41; advanced, 0.40-0.21; far advanced, less than 0.20. In the normal group the diameter of the inferior temporal vein was the largest, followed by that of the superior temporal vein, the inferior temporal artery, and the superior temporal artery. The diameters of the inferior and superior temporal retinal artery were significantly smaller at the early and medium stage, respectively, whereas both inferior and superior temporal retinal vein diameters were significantly smaller at the far advanced stage. The diameters of the inferior and superior temporal retinal arteries correlated significantly with neuroretinal rim area (r > or = 0.48, P = 0.0001), mean deviation (r > or = 0.42, P = 0.0001), vertical cup-to-disc ratio (r < or = -0.33, P = 0.0001), and peripapillary atrophy data (r < or = -0.14, P < 0.04). The results indicate that in primary open-angle glaucoma, vessel diameter becomes less as neuroretinal rim area decreases and visual field defects and peripapillary atrophy increase. Its evaluation can be helpful for the diagnosis of glaucoma and possibly also during follow-up.

Chi-Square Distribution↗
PubMed1975

[Influence of occlusion of retinal vessels on the transport of 22Na and 131J-iodo-o-hippurate out of the subretinal space (experiments performed on cats) (author's transl)].

By means of microsurgical technique and under the control of the ophthalmoscope 300 mul of isotone solution of NaCl with 22Na or o-131J-iodo-hippuric acid were injected into the space between the retina and pigment epithelium of 28 narcotized tomcats after having closed the inferior retina vessels by photocoagulation about 1 hr before in an umber of the animals. With 22Na we could demonstrate that the retinal vessels influence the speed of the transport of substances out of the space between retina and pigment epithelium: When the retina vessels are closed, the transport is decelerated. The same experiments with o-131J-iodo-hippuric acid did not show any difference between the eyes with coagulated vessels and those with open ones. We cannot answer the question, whether sodium is transported in a mono-directional flux out of the space between retina and pigment epithelium (probably followed by water), or if there is simply an exchange between 22Na out of this space with 22Na of the blood.

Animals↗
PubMed1987

Localization of laminin to retinal vessels of the rat and mouse using whole mounts.

Using a whole mount procedure in adult and neonatal mice and adult rats, we have developed an immunohistochemical method for the localization of laminin-like immunoreactivity (LLIR) to the retinal vessels. LLIR was localized to the vascular basement membrane, permitting a clear three-dimensional view of the retinal vasculature. Positive stain was seen in the inner limiting membrane, in retracted capillaries, encasing pericytes, and in a banding pattern on retinal arterioles. The major findings with the whole mount preparations were confirmed using paraffin-embedded material, with the additional observation of LLIR in the lens capsule. In whole mounts of retinas from neonatal mice, LLIR was present from the earliest stages of capillary growth, indicating that laminin is likely to be secreted by endothelial cells during retinal angiogenesis. LLIR within the retinal nerve fiber layer does not precede capillary ingrowth, so no evidence was found that laminin acts as a tracker signal for retinal angiogenesis.

Animals↗
PubMed2004

Ophthalmodynamometric determination of the central retinal vessel collapse pressure correlated with systemic blood pressure.

AIMS: To evaluate whether determination of the central retinal artery and vein collapse pressure correlate with systemic blood pressure measurements, using a new Goldmann contact lens associated ophthalmodynamometric device METHODS: The prospective clinical study included 92 eyes of 92 patients presenting with cataract or refractive problems (n = 40; control study group) or with retinal and orbital pathologies (n = 52). With topical anaesthesia, a Goldmann contact lens fitted with a pressure sensor in its holding ring was placed onto the cornea. Pressure was asserted onto the globe by pressing the contact lens, and the pressure value at the time when the central retinal artery and vein started pulsating were noted as central retinal artery and vein collapse pressure. Additionally, the brachial arterial blood pressure was measured. RESULTS: In the control study group, central retinal artery collapse pressure was highly significantly correlated with diastolic blood pressure (correlation coefficient r = 0.77; p<0.001) and systolic blood pressure (r = 0.35; p = 0.03). Central retinal vein collapse pressure was statistically independent of diastolic blood pressure (p = 0.11). In eyes with retinal or orbital diseases, the correlation coefficients were lower than in the control study group. In eyes with retinal arterial occlusions, central retinal vessel collapse pressure measurements were not correlated with arterial blood pressure measurements. CONCLUSIONS: Depending on coexisting retinal or orbital diseases, ophthalmodynamometric estimation of the central retinal artery collapse pressure, performed during a routine Goldmann contact lens ophthalmoscopy, correlates with systemic blood pressure measurements.

Adult↗
PubMed1980

Bilateral optic nerve hypoplasia with unilateral retinal vessel abnormality.

Optic nerve hypoplasia is an uncommon congenital defect of the optic nerve and retina, although recent studies show it occurs more frequently than previously thought. It is characterized by a small, pale optic disc, normal appearing retinal vasculature, and marked visual impairment. This condition may be unilateral or bilateral and familial cases have been described. It may be associated with other defects of the central nervous system but also occurs in otherwise normal individuals. It is different from aplasia of the optic nerve in which there is complete absence of the optic disc and retinal vasculature, usually in a badly malformed eye. The purpose of this communication is to describe the clinical and fluorescent appearance of an infant with bilateral optic nerve hypoplasia and the unilateral abnormality of retinal vessels.

Electroretinography↗
PubMed2001

Association of retinal vessel caliber and visual field defects in glaucoma.

PURPOSE: This study evaluates the asymmetry of peripapillary retinal vessel caliber between inferior and superior hemispheres in eyes with visual field defects predominantly in one hemifield. DESIGN: Observational case series. METHODS: In a retrospective study, 64 eyes of 64 patients with primary open-angle glaucoma who had a marked difference in visual field defects between hemifields and who had no history of diabetes, trauma, or vascular occlusive disease were studied. The diameters of the superior and inferotemporal vessels were measured at the optic disk border with calipers on an enlarged image. RESULTS: In 64 eyes, the average ratio of the superior temporal artery diameter to inferotemporal artery diameter was significantly greater in the eyes with predominantly superior visual field defects as compared with those with inferior defects (1.10 +/- 0.22 vs. 0.92 +/- 0.19, respectively, P =.002, two-tailed t test). This indicates that the arteriole corresponding to the hemifield with the greater visual field defect was narrower than the arteriole in the other hemifield. This relationship was confirmed using chi(2) analysis (P =.002) comparing the proportions of eyes with ratios greater or less than normal vessel caliber ratios (normal ratio = 0.95 from data reported by Jonas and associates to the location of the dominant field defect. No statistically significant relationship was detected between retinal vein diameter and localized visual field defects, as determined by both the unpaired t test and chi(2) analysis. CONCLUSION: In eyes with primary open-angle glaucoma, this study demonstrates a strong association between decreased peripapillary arteriole diameter and visual field defects in the corresponding hemifield. This reflects either an ischemic basis for glaucomatous damage or vascular constriction when there are fewer axons to nourish.

Adult↗
PubMedDate not supplied

Fluorescence angiography of the paramacular retinal vessels and altered glomerular basement membrane in children with juvenile onset diabetes mellitus.

Eighteen diabetic children aged between 8.5 and 16.5 years (mean 12.5 years) who had been diabetic for 1 to 10 years (mean 4.1 years) were examined for their urinary glomerular basement membrane (GBM) antigen excretion by means of immunoelectrophoresis and for alterations of the retinal vessels by fluorescence angiography. None of these patients showed albuminuria or hypertension. As compared to 40 healthy controls aged between 5 and 17 years, altered GBM antigen mobility (alpha-1) was found in 9 out of these 18 diabetics, whereas the remaining 9 children had normal GBM antigen mobility (alpha-2). Pathological fluorescence angiography findings on the other hand were evident in 7 children with altered GBM mobility, but only in 4 diabetics with normal GBM antigen mobility. This trend reflects the similarity of biochemical and functional characteristics of basement membranes in the retinal and kidney vessels supporting the well established association of vascular changes in both organs in patients with diabetes mellitus. GBM antigen excretion into urine could be useful for detecting early microvascular alterations in the kidneys in juvenile diabetics where diagnosis of early glomerulosclerosis is important.

Adolescent↗
PubMed2006

[Variance of retinal vessel diameter response to flicker light. A methodical clinical study].

AIM: The study investigated the variance of the retinal vessel response to flicker light between the right and left eyes and after a short and a medium-length time interval. METHODS: The prospective study included 28 volunteers. In the first exam both eyes were examined. One eye selected randomly was measured again after 1 h and after 1 month. The diameter response of an arterial and venous vessel segment was measured continuously by a Dynamic Vessel Analyzer (DVA, IMEDOS, Jena). Each examination consisted of 50 s baseline measurement and three periods of 20-s flicker light provocation followed by 80 s observation. The mean of three provocational cycles was calculated as dynamic vessel response. RESULTS: A significant correlation of the flicker response parameters between the right and left eyes was found. Arterial and venous baseline diameter, flicker light dilation, AVDQ, and BP did not change significantly between the first and follow-up examinations. There was no correlation between changes of BP and changes of vessel diameter parameters in the follow-up exams. CONCLUSION: Flicker-evoked dilation of retinal arterioles measured by the DVA is characterized under similar conditions by small variance after short and medium-length time periods. Therefore, this parameter is suitable as a functional parameter of the regulation ability of retinal arteries.

Anatomy, Cross-Sectional↗
PubMed2002

Luminal characteristics of central retinal vessels in the anterior optic nerve of the young human.

PURPOSE: To study the luminal characteristics of the central retinal vessels of young humans where the vessels pass through the anterior optic nerve. METHODS: Serial sections of nine central retinal arteries (CRAs) and 13 central retinal veins (CRVs) from 12 eyes of 12 young donors (aged 20-29 years) without known ocular disease or anatomic malformation were examined by image analysis to determine their luminal dimensional differences right at, anterior to, and posterior to the lamina cribrosa. RESULTS: The average values of the mean area of the CRAs in the prelaminar, laminar, and retrolaminar portions were 16.5 x 10(3) microm2, 17.2 x 10(3) microm2, and 15.2 x 10(3) microm2, and mean perimetric lengths were 541 microm, 528 microm, and 492 microm, respectively. Differences were detected in perimetric length and theoretical luminal area between the laminar and retrolaminar portions, but not the prelaminar and laminar portions. The average values of the mean area of the CRVs in the prelaminar, laminar, and retrolaminar portions were 24.6 x 10(3) microm2, 13.3 x 10(3) microm2, and 7.8 x 10(3) microm2, and mean perimetric lengths were 689 microm, 544 microm, and 411 microm, respectively. There were marked differences between the prelaminar and laminar values and between the laminar and retrolaminar values in terms of the perimetric lengths and theoretical luminal areas. CONCLUSIONS: The results suggest that the resistance of blood flow in CRAs decreases when the blood enters the eye. The gradual constriction of CRVs from the prelaminar to the retrolaminar portion may act as a throttle mechanism in controlling the outflow of the blood and in maintaining the patency of the retinal venules and capillaries.

Adult↗
PubMed1988

Effects of intensified insulin treatment on retinal vessels in diabetic patients.

Forty-five diabetic patients were randomly assigned to treatment with continuous subcutaneous insulin infusion (CSII), multiple injections (MI), and conventional insulin treatment (CIT). They were prospectively followed up for one year. A computerised scanning microdensitometer was applied on fundus photographs of retinal vessels, and we studied changes in calibres of the blood column (W0) and in width (Wr/W0) and intensity (Ir) of the central 'light reflex'. After six months of improved metabolic control the Ir was reduced in both MI and CSII cases compared with CIT cases (p less than 0.01), indicating haemorrheological changes in the retinas. Within these six months cotton-wool spots appeared in half the patients (n = 15) on CSII and MI, but not in CIT patients. Subjects who developed cotton-wool spots, compared with those who did not, had greater intensities of reflection and larger calibres of vessels at the start of the study (p less than 0.01). On intensifying the treatment they were characterised by a larger fall in hemoglobin A1 (p less than 0.01) and by a larger decrease in Ir on arteries (p less than 0.05) and veins (p less than 0.01). The behaviour of the retinal circulation is different in patients developing transient ischaemic lesions on intensified insulin treatment from its behaviour in those who do not.

Adolescent↗
PubMed1989

[Observation of erythrocyte flow in retinal vessels during fluorescein angiography].

Erythrocytes do not take up fluorescein intracellularly during angiography, they are hypofluorescent compared to blood plasma. This negative staining phenomenon has not been observed in the human retina. Scanning Laser Ophthalmoscopy permits imaging of the retina with a higher temporal and a higher spatial resolution than a conventional funduscamera. Thus, the retinal erythrocyte flow can be observed during fluorescein angiography. The red blood cells are seen as multiple black dots in a superficial layer of the intravasal blood column. A pathologically reduced blood flow can be recognized by simple observation. The velocity of the red blood cells is estimated with an erythrocyte velocimeter, that permits an optical comparison between the velocity of black dots and the velocity of the cells in the retinal vessel. The measured values fit well to the data obtained with the laser doppler technique. Therefore, the negative staining phenomenon in association with scanning laser ophthalmoscopy gives us a new tool in retinal microcirculation research.

Erythrocytes↗
PubMed2002

Expression of the murine msr/apj receptor and its ligand apelin is upregulated during formation of the retinal vessels.

We have recently identified a new G protein-coupled receptor, msr/apj, whose transcripts are detected in the endothelium of the primary blood vessels and the newly forming heart (Mech. Dev. 1999;84:199). Its expression during formation of the embryonic vasculature incited us to investigate whether expression of the receptor also increased during the formation of retinal vessels, which occurs postnatally in the mouse. Interestingly, msr/apj transcripts are indeed associated with the forming vessels and trace the centrifugal extension of the superficial vasculature. We also show that expression of the endogenous ligand apelin is upregulated at the leading edge of vessel formation.

Adipokines↗
PubMed1993

Facioscapulohumeral syndrome with sensorineural hearing loss and abnormality of retinal vessels.

A 23-year-old man was recognized as a sporadic case of facioscapulohumeral syndrome (FSH syndrome). He was a case of early onset, and there was severe atrophy of skeletal muscles, although muscle biopsy was normal. Electromyogram revealed neurogenic changes. This patient also had severe sensorineural hearing loss and a mild abnormality of retinal vessels. It is known that some FSH dystrophy or FSH spinal muscular atrophy patients have such coincidental complications. The cause of these coincidences is still unclear, but their occurrence suggests the pleiotropy of the FSH syndrome.

Adult↗
PubMed1985

Blood velocity and volumetric flow rate in human retinal vessels.

The distributions of blood velocity and volumetric flow rate in individual vessels of the normal human retina were determined as a function of vessel diameter. The mean velocity of blood, Vmean, was calculated from the centerline velocity measured by bidirectional laser Doppler velocimetry (LDV). Volumetric flow rate was determined from Vmean and the vessel diameter, D, measured from monochromatic fundus photographs. Diameter of the arteries and veins at the site of the LDV measurements ranged from 39 to 134 microns and 64 to 177 microns, respectively. Flow velocity correlated with D (P less than 0.001 for both arteries and veins). Volumetric flow rate varied with D at a power of 2.76 +/- 0.16 for arteries and 2.84 +/- 0.12 for veins, in close agreement with Murray's law. Calculated from 12 eyes, the average total arterial and venous volumetric flow rates were 33 +/- 9.6 and 34 +/- 6.3 microliters/min, respectively. The good agreement between both flow rates suggests that the technique and the assumptions for calculating flow yield results that satisfy mass conservation. Total arterial and venous volumetric flow rates correlated with total arterial and venous vessel cross-section. Volumetric flow rate in the temporal retina was significantly greater than in the nasal retina, but the difference is likely to be due to the larger area of the temporal retina. No difference in flow rate was observed between the superior and inferior retinal hemispheres. Finally, blood velocity in the major retinal vessels measured under normal experimental conditions appears remarkably constant over short (hours) and long (months) periods of time.

Blood Flow Velocity↗
PubMed2001

[Blood flow in retinal vessels of normal-tension glaucoma with or without a history of optic disc hemorrhages].

PURPOSE: To evaluate blood flow in retinal vessels of normal-tension glaucoma (NTG) with or without a history of optic disc hemorrhages (DH) and compare it with that in non-glaucomatous eyes using scanning laser fluorescein video angiography. METHODS: We enrolled 14 eyes of 14 NTG patients with a history of DH (DH (+) group), 12 eyes of 12 NTG patients without history of DH (DH (-) group), and 10 eyes from 10 non-glaucomatous patients matched for age, intraocular pressure, and systemic blood pressure. No statistically significant difference was observed between the DH (+) and DH (-) groups of NTG in the global indices of the Humphrey visual field. Fluorescein angiography was performed using a scanning laser ophthalmoscope with an argon blue laser. A series of approximately 100 consecutive video images at 1/2 second intervals from just before the dye appearance in the central retinal artery was loaded into an external personal computer system. Based on this acquired image series, we obtained fluorescein filling curves for 10 x 10 pixel measuring areas placed on each of the superior-temporal and inferior-temporal branch retinal arteries and veins at 1/5 papillary diameter from the disc edge. In each vessel, time to the highest fluorescein intensity (peak time, sec) and the time constant of the filling curve (tau, sec) were obtained. Time difference between the peak times in vein and artery (peak time difference) was also calculated. RESULTS: Statistically significant differences were observed among the three groups in the peak time of inferior-temporal artery and vein, and superior-temporal vein (ANOVA, p < 0.01). Also there were statistically significant differences in the tau of all vessels (ANOVA, p < 0.05). No statistically significant differences were observed in the peak time differences. By multivariate analysis, the DH (+) and DH (-) groups of NTG showed significantly longer peak times and tau s than did the non-glaucomatous eyes (p < 0.05). However, no statistically significant differences were observed in any parameters between the DH (+) and DH (-) groups of NTG. CONCLUSIONS: In NTG, dye filling rate in both the central retinal arteries and veins seems to be delayed. However, this delay does not differ between DH (+) and DH (-) groups.

Aged↗