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PubMedDate not supplied

Gray-white, spherical deposition on retinal vessel associated with acute retinal necrosis and diabetic retinopathy in HTLV-I carriers.

Tiny, gray-white, spherical deposits were found on the retinal vessels and vitreoretinal interface of the fovea in a 55-year-old woman with acute retinal necrosis due to varicella-zoster virus, and in a 47-year-old man with preproliferative diabetic retinopathy. Both patients developed massive vitreous opacities due to uveal inflammation or hemorrhages that rendered the fundus difficult to visualize. A therapeutic vitrectomy revealed gray-white, tiny spherical deposits, about blood-vessel-diameter, which were scattered on seemingly intact retinal arteries and veins in the posterior fundus and over the vitreoretinal interface overlying the fovea. The deposits were loosely adherent to vessel walls and were easily aspirated, and the residual materials resolved in the early postoperative days. These characteristic retinal vascular deposits resembled those seen in patients with HTLV-I associated uveitis. The two patients reported herein were otherwise asymptomatic carriers of HTLV-I. The findings provide additional information about the etiological role of HTLV-I in the development of characteristic retinal vascular deposition, although its pathogenesis remains to be elucidated.

Carrier State↗
PubMed2002

Retinal Vessel Analysis--new possibilities.

Retinal Vessel Analysis is a new technique to assess behavior of large retinal vessels based on diameter measurements. The Retinal Vessel Analyzer (RVA) measures continuously on-line obtaining data in relation to time and local position. Possible analysis tools include (a) Time Course Analysis of physiological, pathological, or therapy induced changes; (b) Local Course Analysis to recognize local narrow or wide vessel segments along the vessel; (c) Vasomotoric Analysis to determine vasomotions and blood pressure related diameter changes; (d) Functional Analysis to examine dynamic behavior e.g. the ability to autoregulate and (e) Functional Imaging to visualize functional parameters of vessels in single vessel segments. RVA is thus able to recognize and study different autoregulation mechanisms.

Fluorescein Angiography↗
PubMed1992

[Two cases of isolated avulsed retinal vessels].

Two cases of isolated avulsed retinal vessels without retinal breaks or any other vitreoretinal disorders are reported. Case 1: a 57-year-old woman developed acute vitreous hemorrhages in the right eye associated with an avulsed retinal artery in the superior equatorial region. Case 2: a 74-year-old man had an asymptomatic avulsed retinal vein in the superior midperiphery. Repeat argon laser photocoagulation resulted in uncomplicated occlusion of the avulsed retinal vessels and reduced the risk of recurrent vitreous hemorrhage.

Aged↗
PubMed1994

[Laser speckle velocimetry of retinal blood flow with simultaneous measurement of retinal vessel diameter].

A new retinal blood flowmeter, by which the real-time measurement of retinal vessel diameter and laser speckle retinal blood flow velocimetry could be performed simultaneously, was developed and the reproducibility of the measurements was studied for 16 retinal veins of 8 eyes (4 normal volunteers). The experiment was performed on all veins measured three times in 2 days. The first 2 measurements were performed on the first day at an interval of about 2 hours and the third measurement was performed on the second day. The result of each measurement was compared with the others. The reproducibility of retinal blood flow velocity measurements was 5.53 +/- 2.15% (mean +/- standard deviation) in coefficient of variation (CV), that of blood vessel diameter measurements was 3.06 +/- 1.58% in CV, and that of blood flow measurement was 5.54 +/- 2.10% in CV. The fluctuation between the three measured data was 10.50 +/- 7.25% (mean +/- standard deviation), 10.01 +/- 6.98%, 11.60 +/- 6.47% in the retinal blood flow velocity measurements, 6.34 +/- 4.40%, 5.71 +/- 4.49%, 4.46 +/- 4.36% in the retinal blood vessel diameter measurements, and 6.59 +/- 8.36%, 10.76 +/- 8.91%, 9.72 +/- 4.42% in the retinal blood flow measurements. This method enabled more precise measurement of the retinal blood flow than previously reported methods.

Adult↗
PubMed2000

Clinical-histopathological correlation of the abnormal retinal vessels in cerebral malaria.

BACKGROUND: Clinically abnormal retinal vessels unique to cerebral malaria have previously been shown to be associated with a poor outcome in African children. There have been no studies of the histopathological correlates of these vessels. DESIGN: This is a descriptive study of the clinical-histopathological correlates of the retinal vessels of 11 children who died with cerebral malaria. RESULTS: The retinal vessels in children with cerebral malaria contained many parasitized red blood cells; these cells tended to cluster at the periphery of vessels or, in the case of capillaries, to fill the vessel. Those with late-stage parasites had markedly reduced amounts of hemoglobin. The pattern of dehemoglobinization corresponds to the pattern of clinically abnormal vessels. CONCLUSIONS: The sequestration of late-stage parasitized red blood cells with reduced amounts of hemoglobin accounts for the unique white and pale orange retinal vessels seen in cerebral malaria. Clinical examination of these "marked" vessels offers a method to monitor a basic pathophysiological process of cerebral malaria in vivo. Arch Ophthalmol. 2000;118:924-928

Animals↗
PubMed1975

[The condition of the retinal vessels and intraocular and retinal pressure in patients with incipient forms of cerebrovascular atherosclerosis].

The authors examined 350 patients with initial forms of cerebrovascular atherosclerosis. Among the studied group 98 had discirculatory disorders. All patients were studied for the eye ground, intraocular and retinal pressure. The following clinical symptoms characterized this group of patients: antigiospasms, organic changes in the arterial vessels of the retina, changes in the peripapillar zones, in a normal eye retraction, a drop in the diastolic retinal pressure. Glaucoma was depicted in 27%. In patients with a tendency to cerebral paroxysms and transient disorders of cerebral circulation there were more distinct and more frequent symptoms of angiospasms, as well as signs of organic changes in the retinal arteries. The authors mark an increase in the systolic and retinal pressure and an asymmetry of it. Glaucoma was depicted in 3% of the cases.

Adult↗
PubMed2005

Medication use and retinal vessel diameters.

PURPOSE: To study the influence of different medications on retinal vessel diameters. DESIGN: Cross-sectional study. METHODS: Retinal photographs in the Beaver Dam Eye Study (n = 4926, aged 43 to 84 years) were digitized, and the diameters of retinal vessels were measured. Participants' current medications were recorded at the examination. RESULTS: There were few significant associations between medication use and retinal vessel diameters. After adjusting for age, blood pressure, and other factors, participants who were using topical beta-blocker eyedrops had narrower retinal arteriolar (P = .05) and venular (P = .006) diameters than nonusers. Systemic beta-blocker was not associated with retinal vessel diameter size. CONCLUSION: We found few associations between current medication use and retinal vessel diameter. Retinal vessels were narrowed in those taking antiglaucoma medications, most strikingly in those prescribed topical beta-blockers, although such a relationship could not be established among those using systemic beta-blockers.

Adult↗
PubMed2006

[Avulsed retinal vessels].

PURPOSE: To describe the clinical evolution of cases with avulsed retinal vessels without retinal detachment treated with laser or scleral buckle. METHODS: Retrospective analysis of cases with avulsed retinal vessels treated between 2001-2003. Laser photocoagulation or scleral buckle was used. The minimum follow-up was 6 months. Average age was 53.6 years. RESULTS: Of 13 patients, 8 were photoagulated with argon laser and 5 were submitted to a scleral buckle. The most common symptom was reduction in visual acuity. Vitreous hemorrhage was present in 7 eyes (53.8%) at diagnosis, and was the most frequent complication after treatment (30.7%). Final visual acuity was unchanged. CONCLUSION: Avulsed retinal vessels have a good prognosis using laser or buckle. Late vitreous hemorrhage was the main complication.

Adult↗
PubMed1997

Role of astrocytes in the control of developing retinal vessels.

PURPOSE: To assess the role of astrocytes in controlling the growth of developing retinal vessels. METHODS: Growth of retinal vessels in the neonatal rat retina was examined in three conditions: normal development, cyclic hyperoxia, and normoxia (1 day 70% to 75% oxygen, 1 day room air for up to seven cycles from birth, and room air for up to 16 days), and direct hypoxia (10% oxygen from postnatal day 3 [P3]). Retinas were examined as wholemounts labeled for astrocytes, microglia, and blood vessels and in some experiments for the fragmentation of DNA characteristic of apoptosis. RESULTS: In normoxia, superficial retinal vessels formed to the processes of astrocytes. In cyclic hyperoxia, the depletion of superficial retinal vessels and subsequent neovascularization described by others were confirmed. The neovascularization was preceded by the depletion by apoptotic death of the astrocyte population, first between vessels but eventually breaching the glia limitans along vessels. The earliest forms of neovascularization resembled microaneurysms, each protruding through a defect in the glia limitans of a capillary. Neurons of the ganglion cell layer survived. Direct hypoxia from P3 caused hypertrophy of superficial vessels. Between P3 and P6, some vessels accelerated past the still-spreading astrocytes, often growing out of the retina into the vitreous humor. Direct hypoxia also caused astrocyte degeneration, but capillaries retained astrocyte investment and were not the site of vascular damage. By P8, breaches in the astrocytic glia limitans became prominent but were restricted to large veins. At such breaches, bleeding into the vitreous humor was common. CONCLUSIONS: Retinal vessels normally develop in close association with astrocytes. Where that association is broken, preretinal vessels may grow or bleed into the vitreous humor. Astrocytes play important roles in constraining retinal vessels to the retina and in maintaining their integrity.

Animals↗
PubMed2005

The clinical study of congenital looped/coiled peripapillary retinal vessels.

PURPOSE: To present clinical manifestations of eyes with peculiar looped/coiled peripapillary retinal vessels. METHODS: Seven patients with looped/coiled retinal vessels on or near the optic disc were enrolled. All patients went through detailed ophthalmologic examinations and fluorescein angiography (FAG). RESULTS: There were two men and five women. Patients' age ranged from 15 to 71 years (mean: 39 years). The follow-up period ranged from 3 to 74 months (average: 27 months). One patient had bilateral involvement. Five of the seven patients noticed sudden onset of floaters in one eye. The colour fundus photography revealed looped/coiled retinal vessels on or near the optic disc, and most of the vessels were arteries. Accompanied retinal, preretinal, or vitreous haemorrhage was noted in all five patients who had sudden onset of floaters. Fluorescein angiography showed no leakage from the looped/coiled retinal vessels. No specific underlying diseases were noted in any patients. Follow-up examination revealed reabsorption of haemorrhage, and no change of the abnormal vessel patterns in any eyes. CONCLUSIONS: The peculiar fundus lesion of looped/coiled peripapillary retinal vessels is likely a benign congenital retinal vascular anomaly that does not progress. Floaters secondary to preretinal or vitreous haemorrhage is the most frequent complaint. The prognosis is excellent.

Adolescent↗
PubMed2000

Evaluation of the Zeiss retinal vessel analyser.

AIM: To investigate the reproducibility and sensitivity of the Zeiss retinal vessel analyser, a new method for the online determination of retinal vessel diameters in healthy subjects. METHODS: Two model drugs were administered, a peripheral vasoconstrictor (the alpha receptor agonist phenylephrine) and a peripheral vasodilator (the nitric oxide donor sodium nitroprusside) in stepwise increasing doses. Nine healthy young subjects were studied in a placebo controlled double masked three way crossover design. Subjects received intravenous infusions of either placebo or stepwise increasing doses of phenylephrine (0.5, 1, or 2 microg/kg/min) or sodium nitroprusside (0.5, 1, or 2 microg/kg/min). Retinal vessel diameters were measured with the new Zeiss retinal vessel analyser. Retinal leucocyte velocity, flow, and density were measured with the blue field entoptic technique. The reproducibility of measurements was assessed with coefficients of variation and intraclass correlation coefficients. RESULTS: Placebo and phenylephrine did not influence retinal haemodynamics, although the alpha receptor antagonist significantly increased blood pressure. Sodium nitroprusside induced a significant increase in retinal venous and arterial diameters (p<0.001 each), leucocyte density (p=0.001), and leucocyte flow (p=0.024) despite lowering blood pressure to a significant degree. For venous and arterial vessel size measurements short term coefficients of variation were 1.3% and 2.6% and intraclass correlation coefficients were 0.98 and 0.96, respectively. The sensitivity was between 3% and 5% for retinal veins and 5% and 7% for retinal arteries. CONCLUSIONS: These data indicate that the Zeiss retinal vessel analyser is an accurate system for the assessment of retinal diameters in healthy subjects. In addition, nitric oxide appears to have a strong influence on retinal vascular tone.

Adrenergic alpha-Agonists↗
PubMed2004

Computer-assisted measurement of retinal vessel diameters in the Beaver Dam Eye Study: methodology, correlation between eyes, and effect of refractive errors.

OBJECTIVE: Narrowed retinal arterioles may independently predict cardiovascular disease. We describe a computer-assisted method to measure retinal vessel diameters from digitized fundus photographs in a large population, and examine the correlation of retinal vessel diameters between eyes and whether refractive errors affect these measurements. DESIGN AND POPULATION: Population-based, cross-sectional study in Beaver Dam, Wisconsin (n = 4926; age, 43-84 years). METHODS: Retinal photographs were digitized, and all arterioles and venules located in an area 0.5 to 1 disc diameter from the optic disc were measured with the aid of computer software. MAIN OUTCOME MEASURES: Summary of retinal arteriolar and venular diameters, and the ratio of their diameters (arteriole:venule ratio [AVR]). RESULTS: Correlation between right and left eyes was substantial for retinal arteriolar diameters (Pearson correlation coefficient, rho = 0.71) and venular diameters (rho = 0.74), and moderate for the AVR (rho = 0.49). The inverse association of higher blood pressure and smaller retinal arteriolar diameters was similar using data from either one eye or two eyes; arteriolar diameters decreased by 4.1 microm (right eyes), 4.0 microm (left eyes), and 4.0 microm (mean of both eyes) with each 10-mmHg increase in mean arterial blood pressure. A myopic refraction was associated with smaller retinal vessel diameters; arteriolar diameters decreased by 2.8 microm and venular diameters by 3.3 microm with each -1.0-diopter shift towards myopia. However, the pattern and strength of the association of blood pressure and retinal vessel diameters were not altered by variations in refractive errors. CONCLUSIONS: There is good correlation of retinal vessel diameters between eyes. A myopic refraction is associated with smaller retinal vessel diameters. The association of retinal arteriolar diameters and blood pressure seems similar using data from either one eye or two eyes, and is minimally affected by refraction. These data suggest that measurement of retinal vessel diameters from one eye without regard to its refractive status may provide adequate information indicative of a person's retinal vessel caliber if information from two eyes and refraction is unavailable.

Adult↗
PubMed1990

[A method for recording the network topology of human retinal vessels].

Network analysis of the human retinal vessels must be based on a thorough knowledge of the topology of the network. This derives from the numerical composition of the network's individual components. Using histologic specimens, centrifugal and centripetal ordering methods were compared. It was found necessary to use an ordering system which takes both dichotomous as well as lateral branching into account, and Strahler's centripetal ordering system was found to be suitable. For various representative areas of human retinae it could be shown that the number of segments of each Strahler order forms an inverse geometric sequence which enables the Horton branching quotient RB to be calculated. It is thus possible to predict the number of vessel segments within the individual orders. Although the method ignores detailed vessel morphology, with knowledge of the vessel lengths and diameters determined in the same manner it enables the conductivity and resistance of human retinal vessels to be measured.

Blood Viscosity↗
PubMed2000

Optical model of the blood in large retinal vessels.

Several optical techniques that investigate blood contained within the retinal vessels are available or under development. We present a mechanical model that simulates the optical properties of the eye, the retinal vessels, and the ocular fundus. A micropipette is chosen as the retinal vessel model, and a mechanical housing is constructed to simulate the eyeball. Spectralon is used to simulate the retinal layers. Filling the eye with fluid index matched to the glass pipette eliminates reflection and refraction effects from the pipette. An apparatus is constructed and used to set the oxygen, nitrogen, and carbon dioxide concentrations in whole human blood. These whole blood samples are pumped through the pipette at 34 microL/min. Measurements made in the model eye closely resemble measurements made in the human eye. This apparatus is useful for developing the science and testing the systems that optically investigate blood and blood flow in the large retinal vessels.

Blood Flow Velocity↗
PubMed2004

Effect of laser photocoagulation on the retinal vessel diameter in branch and macular vein occlusion.

OBJECTIVE: To investigate the response of retinal vessel diameters to photocoagulation treatment and their role for the success of laser treatment in patients with retinal vein occlusion. METHODS: The study included 14 patients with branch vein occlusion or macular vein occlusion. The ophthalmologic examination included best-corrected visual acuity, biomicroscopy, fundus photography, and fluorescein angiography. Retinal vessel diameters were quantified before and after laser photocoagulation using a retinal vessel analyzer. MAIN OUTCOME MEASURE: Retinal vessel diameters. RESULTS: In cases manifesting macular vein occlusions, no significant change of the vessel diameter in any vessel was observed during the follow-up period. In the group with branch vein occlusion, all vessels tended to constrict after the laser photocoagulation. The effect of laser treatment on retinal vessel diameters was significant for superotemporal (P =.045, analysis of variance [ANOVA]) and inferotemporal branch veins (P =.03, ANOVA). Vasoconstriction was more pronounced in the occluded branch veins (P =.009, ANOVA) compared with the nonaffected veins (P =.12; ANOVA). The change of visual acuity after 3 months was correlated with the change of vessel diameter 3 months after laser treatment for occluded venular branches (r = 0.78, P =.02, linear regression). There was no correlation between the number of laser burns and the change of vessel diameters in the affected veins in this period (r = 0.12, P =.75, linear regression). CONCLUSIONS: Our results show that retinal photocoagulation in patients with branch vein occlusion has a vasoconstrictive effect on occluded veins. The correlation between the change in visual acuity and the change in vessel diameter indicates that branch vein constriction after photocoagulation may be an early indicator of the success of laser treatment.

Aged↗