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PubMedDate not supplied

Retinal vascular and optic nerve abnormalities in albinism.

Albinism is a condition in which the pigment melanin may not be synthesized from tyrosine. The fundus photographs of 24 eyes of 12 patients with the clinical diagnosis of either ocular or oculocutaneous albinism were reviewed. We observed two findings that to our knowledge have not been reported previously. Eighteen eyes of ten patients had prominent retinal vessels coursing through the putative macular area instead of arching around it. Large noncilioretinal vessels extended from the disc to the dysplastic "foveal zone" in eight eyes of five patients. Typical optic nerve hypoplasia (ONH) was seen in six eyes of four patients; features suggestive of ONH were present in an additional ten eyes of six patients. The cross-over (sharing) of clinical features between albinism and aniridia is striking and raises questions about pathophysiologic mechanisms.

Albinism↗
PubMed1992

[Alcohol during pregnancy damages eye and vision development].

Maternal alcohol abuse during pregnancy causes malformations of the eyes with serious consequences to the vision of the affected children. A high percentage (up to 90 per cent) of children suffering from the fetal alcohol syndrome have eye abnormalities of different kinds. The most typical are hypoplasia of the optic nervehead and increased tortuosity of the retinal vessels, especially of the arteries, both occurring in up to half of the cases. Visual acuity is often reduced. Considering the developmental timing of different tissues of the eye, one can presume that there is a risk for deleterious effects of alcohol on eye structures at any point of time from early gestation until development is completed.

Alcoholism↗
PubMed1988

Clinical and immunopathological studies of pars planitis in a family.

We examined a family in which two brothers with identical HLA typing have pars planitis with snowbanking. Immunopathological studies of one of their eyes showed that in the area of snowbanking over the pars plana there was mild to moderate inflammatory cell infiltration, consisting of mostly Pan T (Leu 4+) lymphocytes. The ratio of T helper/inducer to T suppressor/cytotoxic cells was approximately 10:1. Few macrophages (OKM1+) were identified. Very few B cells and no NK cells were observed. Some retinal vessels had a perivascular infiltration consisting of mostly T lymphocytes. Most of the inflammatory cells bore class II antigens (HLA-DR+), while T cells bore few IL-2 receptors (anti-TAC+). The snowbank consisted mainly of glial elements (GFAP+) and basement membrane components (type IV collagen and laminin) with the predominant cell the Müller cell (Mü+). A site of inflammation at the iris-ciliary body junction also stained for B cells (Leu 14+). These findings suggest that the snowbank could be formed by the glial elements of the peripheral retina. The chronic inflammation in pars planitis appears to consist of helper T cells, both in the pars plana, and the retinal vasculature.

Adolescent↗
PubMed2004

Effects of brinzolamide on ocular haemodynamics in healthy volunteers.

AIM: A prospective, randomised study to evaluate effects of brinzolamide on ocular haemodynamics in healthy volunteers. METHODS: 30 volunteers (12 men, 18 women; 28.3 (SD 7.8) years) were prospectively randomised to either brinzolamide or placebo during a 2 week double masked treatment trial. Examinations were performed at baseline and after 2 weeks of treatment. Intraocular pressure was measured and automatic static perimetry (Humphrey field analyser, 24-2) and contrast sensitivity (CSV 1000, Vector Vision) were performed. Retrobulbar blood flow velocities (peak systolic and end diastolic velocity) and resistive indices (RI) of ophthalmic artery, central retinal artery and of temporal and nasal short posterior ciliary arteries were measured by colour Doppler imaging (Sonoline Sienna Siemens). In video fluorescein angiograms (scanning laser ophthalmoscope, Rodenstock) arteriovenous passage time (AVP, dilution curves) and peripapillary diameters of retinal arterioles and venules were measured by means of digital image analysis. RESULTS: Intraocular pressure was significantly decreased by brinzolamide (p<0.0001). Neither brinzolamide nor placebo changed visual field global indices after treatment. Contrast sensitivity at 3 cycles per degree was significantly higher in the placebo group (p<0.05). Apart from an increase of RI in ophthalmic artery under placebo treatment (p<0.05) there was no effect in retrobulbar haemodynamics in both groups. Brinzolamide therapy alone resulted in a significant reduction of AVP compared to baseline (p<0.05), while peripapillary retinal vessels diameters remained unaffected. CONCLUSIONS: Apart from the expected decrease of intraocular pressure brinzolamide showed no significant change in retrobulbar haemodynamics, but a significant shortening of AVP. Since in glaucoma AVP is prolonged indicating vascular dysfunction this effect might be beneficial in glaucoma therapy.

Adult↗
PubMed2000

Organ damage in treated middle-aged hypertensives compared to normotensives: results from a cross-sectional study in general practice.

BACKGROUND: High blood pressure contributes to organ damage. However, during the past two decades there have been great advances in the medical treatment of hypertension. Technical progress has also made it easier to visualize organ damage. Hence we found it of interest to examine heart, brain and retina in a group of middle-aged treated hypertensives, comparing the results with those from a group of middle-aged normotensives. METHODS: The subjects were 40 (20 men) treated hypertensives and 40 (20 men) normotensives, who had previously taken part in a study in which ambulatory blood pressure monitoring had been performed. The heart was examined by echocardiography, the retina by photography and the brain by magnetic resonance imaging. RESULTS: Office blood pressure and 24-h systolic/diastolic blood pressure (S/D) were 141/86 (13/7) mmHg and 128/81 (11/6) mmHg in the hypertensives and 125/78 (10/8) mmHg and 118/74 (8/5) mmHg in the normotensives, respectively. Left ventricular mass was 101 (27) g/m2 in the hypertensives and 85 (18) g/m2 in the normotensives (p = 0.0025). The corresponding figures for the left atrium were 21.1 (3.1) mm/m2 in the hypertensives and 19.5 (2.2) mm/m2 in the normotensives (p < 0.001). E/A wave quotient was 1.09 (0.26) in the hypertensives and 1.26 (0.26) in the normotensives (p = 0.0045), while left ventricular systolic function did not differ between the groups. Ten hypertensives and one normotensive subject had left ventricular mass above normal range. Narrow retinal arteries were found in 22 hypertensives and 8 normotensives (p < 0.001). Brain magnetic resonance changes (deep white matter and/or periventricular) were found in 19 hypertensives and 9 normotensives (p = 0.0431). CONCLUSIONS: The hypertensives differed significantly from the normotensives concerning left ventricular mass, left atrium, left ventricular diastolic function and retinal vessel changes. Deep white matter and periventricular changes in the brain were also significantly different in the two groups. We can only speculate as to whether earlier antihypertensive treatment or further blood pressure reduction could have affected these differences.

Adult↗
PubMed1984

An internist looks at the fundus oculi.

The ophthalmoscope is the only convenient device permitting the in vivo inspection of both neural tissue and the arterial and venous blood columns within the retinal vessels. Many findings of little interest to ophthalmologists are, when integrated into the total clinical examination, of great use to internists during the process of making a specific diagnosis. Even after the diagnosis has been made, some ophthalmoscopic signs are uniquely useful in evaluating the chronicity, severity, prognosis, and/or the vasculopathic effects of the disease.

Aneurysm↗
PubMed1990

Quantitative analysis of retinal hemodynamics using targeted dye delivery.

A new method designed to allow repeated mapping of retinal hemodynamics on a macro- and microcirculatory level was evaluated in the primate eye. The method, called "targeted dye delivery," consists of encapsulating a fluorescent dye in temperature-sensitive liposomes, injecting the liposomes systemically, and using a light pulse from an argon laser to release a bolus of dye in a targeted retinal vessel. The follow-up of the well-defined dye front thus generated allows calculation of the blood flow and capillary transit time. Evaluation of targeted dye delivery in a monkey indicated that centerline blood velocity and the vessel diameter can be measured with a reproducibility of 10% and 4%, respectively, in vessels that are 40 microns and larger. These measurements yielded flow values that had a reproducibility of 10% on the same day and 13% on different days. The normalization of flow rate by the vessel diameter was consistent with theoretic estimates and promises to be a circulation indicator independent of variations between individual and species. The transit time across capillary beds at different locations was found to be similar, thus indicating that the method could be used to evaluate the local viability of the microcirculation.

Animals↗
PubMed1988

Familial oculoleptomeningeal amyloidosis. Report of a new family with unusual features.

A family had a dominantly inherited amyloid angiopathy that involved the meninges of the brain and spinal cord, retina, vitreous humor, peripheral nerves, and systemic organs. Clinical features included hemiplegic migraine, periodic obtundation, psychosis, seizures, intracerebral hemorrhage, myelopathy, visual impairment, deafness, and peripheral neuropathy. Pathological findings consisted of amyloid deposition in the leptomeningeal and retinal vessels, in the vitreous humor, and in perivascular tissue throughout the body. Evaluation of the amyloid showed it to be a transthyretin (prealbumin). A brief course of plasmapheresis produced a short-lived decrease concentration in circulating transthyretin.

Adult↗
PubMed1994

Vascular wall von Willebrand factor in human diabetic retinopathy.

PURPOSE: To reconstruct the role played by vascular endothelium in the elevation of circulating von Willebrand factor (vWf) in diabetic patients with microangiopathy and, specifically, to determine whether storage and synthesis of vWf is altered in diabetic retinal vessels. METHODS: Trypsin digests were prepared from retinas obtained post mortem from 11 patients (age 62 +/- 9 years, mean +/- SD) with 9 +/- 5 years of diabetes and 12 nondiabetic control subjects matched for age and sex. Trypsin digests were inspected for the presence of lesions of diabetic retinopathy; vWf protein was localized by indirect immunofluorescence; and vWf mRNA levels were studied by in situ hybridization. RESULTS: vWf immunofluorescence was present in vessels of all sizes. The granular fluorescence was localized to the endothelial cell cytoplasm. Pattern and intensity of staining in diabetic microvessels and large vessels were similar to those observed in the vessels of nondiabetic subjects. The amount of vWf mRNA detected by in situ hybridization in retinal endothelial cells was similar in diabetic (0.92 +/- 0.32 grains/cell) and control (0.91 +/- 0.42 grains/cell) microvessels. Likewise, no differences were observed in vWf mRNA levels in the large vessels of diabetic (0.073 +/- 0.034% grain area) and control (0.069 +/- 0.018 grain area) subjects. CONCLUSIONS: These observations are compatible with the occurrence in diabetes of the slow release of endothelial vWf through the pathway of vWf secretion not linked to synthesis, ie, the regulated pathway.

Adult↗
PubMed1989

Optic disc neovascularization in dominant exudative vitreoretinopathy.

Dominant exudative vitreoretinopathy (DEVR) is inherited retinal vascular disorder which is characterized by peripheral retinal neovascularization, tractional retinal detachment, subretinal, exudation, and vitreous fibrosis. A milder form of involvement characterized by capillary nonperfusion and straightening of the retinal vessels may be present in asymptomatic individuals. We describe a 15-year-old patient who presented with optic disc neovascularization, a finding not previously reported in association with DEVR. Angiographic evidence of DEVR in successive generations confirmed the diagnosis. The findings in mild and advanced DEVR are reviewed, and the pathogenesis of the capillary nonperfusion is discussed.

Adolescent↗
PubMed1998

Hyperoxia stimulates endothelin-1 secretion from endothelial cells; modulation by captopril and nifedipine.

PURPOSE: Retinopathy of prematurity (ROP) is a vasoproliferative condition that can result in severe visual impairment and blindness in preterm babies. Two conditions seen very early in radioimmunoassay (ROP) are vasoconstriction and vaso-obliteration. A potent vasoconstrictor secreted by endothelial cells is endothelin-1 (ET-1). Premature birth results in a relative systemic hyperoxia, compared to the in utero oxygen milieu. We tested the hypothesis that hyperoxia increases ET-1 expression as a possible mechanism for vasoconstriction in the retinal vasculature. METHODS: Bovine retinal endothelial cells and adrenal capillary endothelial cells were isolated and maintained in culture. Cells were exposed to control or hyperoxic culture conditions for 24 h, with and without addition of captopril and nifedipine. Media was collected and assayed for ET-1 by ROP. In addition, cell counts and secreted LDH assays were performed. RESULTS: Conditioned media from cultured bovine retinal and adrenal endothelial cells exposed to hyperoxic culture conditions for 24 h were found to have higher levels of ET-1 than conditioned media from normoxic control cells. Captopril (10(-6) M and 10(-4) M) and nifedipine (10(-6) M and 10(-4) M) inhibited ET-1 release from hyperoxia-exposed endothelial cells. Under normoxic conditions, ET-1 release was inhibited by 10(-4) M captopril or 10(-4) M nifedipine. CONCLUSIONS: These results demonstrate that (1) hyperoxia stimulates in vitro ET-1 secretion in bovine retinal and adrenal capillary endothelial cells, and (2) captopril and nifedipine downregulate ET-1 secretion under normoxic and hyperoxic culture conditions, in a dose-dependent fashion. We speculate that ET-1 may be involved in retinal vessel vasoconstriction seen early in the development of ROP. Further, ACE inhibitors and calcium-channel blocking agents, such as captopril and nifedipine, may provide an avenue for blocking vasoconstriction in ROP.

Adrenal Glands↗
PubMed1999

Radiation-induced leukocyte entrapment in the rat retinal microcirculation.

PURPOSE: To evaluate the effects of irradiation on leukocyte dynamics in the rat retinal microcirculation. METHODS: Thirty-five Brown-Norway rats received a dose of 10 Gy irradiation in one fraction. Leukocyte dynamics were studied with acridine orange digital fluorography, in which a nuclear fluorescent dye of acridine orange is used and examined by scanning laser ophthalmoscope. This technique allowed visualization of fluorescent leukocytes in vivo. The leukocyte dynamics were evaluated at 0, 4, 7, 14, 30, and 60 days after the irradiation. RESULTS: Mean leukocyte velocity in the retinal capillaries decreased immediately. It partially recovered on day 4 but then gradually decreased up to the 2-month mark. Low-dose irradiation induced entrapment of leukocytes in the retinal microcirculation. The number of entrapped leukocytes gradually increased with time. The major retinal vessels significantly constricted immediately after irradiation. The diameter was reduced by 76% in arteries and 75% in veins, 2 months after irradiation. CONCLUSIONS: Entrapped leukocytes may be activated and exacerbate vascular injury and microinfarction and thus may participate in the pathogenesis of radiation retinopathy.

Acridine Orange↗
PubMed2001

PDGF-induced coupling of function with metabolism in microvascular pericytes of the retina.

PURPOSE: The aim of this study was to test the hypothesis that platelet-derived growth factor (PDGF)-BB regulates the physiology of retinal pericytes, which are contractile cells located on the abluminal surface of capillaries. The expression of PDGF-BB and its cognate receptor in retinal vessels suggests a vasoactive function. However, although endothelium-derived PDGF-BB appears vital for the development of pericyte-containing microvessels, its role in the mature vasculature remains uncertain. METHODS: Based on the premise that ion channels mediate the responses of pericytes to vasoactive signals, the perforated-patch configuration of the patch-clamp technique was used to determine the effect of PDGF-BB on the ionic currents and membrane potential of pericytes located on microvessels freshly isolated from the adult rat retina. Changes in pericyte calcium levels were monitored with the calcium indicator fluo-4. Differential interference contrast optics and image analysis software aided in assessing the effects of PDGF-BB on the lumens of isolated pericyte-containing microvessels. In some experiments, blockers of adenosine triphosphate (ATP) synthesis created chemical ischemia. RESULTS: Electrophysiological recordings from pericytes showed that PDGF-BB can activate nonspecific cation channels, chloride channels, and ATP-sensitive potassium channels. The metabolic status of an isolated capillary determined which of these ion channels were activated by PDGF-BB and thereby whether the membrane potential decreased or increased, the cell calcium rose or fell, and the vessel lumen constricted or dilated. CONCLUSIONS: The ability of PDGF-BB to be a vasoconstrictor when energy supplies are ample and to be a vasodilator under ischemic conditions may provide an efficient mechanism to link capillary function to local metabolic needs.

Aniline Compounds↗
PubMed2002

Idiopathic juxtafoveolar retinal telangiectasis: case report and literature review.

BACKGROUND: Idiopathic Juxtafoveolar Retinal Telangiectasis (IJRT) is a retinal vascular anomaly, characterized by irregular dilation and incompetence of retinal vessels. Although the etiology of the condition is unknown, its various presentations have been characterized into three groups. Treatment includes laser photocoagulation and observation and is based on disease classification. CASE REPORT: The case report presents a patient with Group 2A, Stage 3 IJRT. The clinical appearance, differential diagnosis, and management of IJRT and its subgroups are discussed. CONCLUSION: Appropriate classification of IJRT is essential to the successful management of this condition.

Diagnosis, Differential↗
PubMedDate not supplied

Ocular involvement in the fetal alcohol syndrome.

Maternal alcohol abuse during pregnancy causes malformations of the eyes with serious consequences to the vision of the affected children. A high percentage (up to 90%) of children suffering from the fetal alcohol syndrome have eye abnormalities, including malformation in the outer eye region, disorders of motility, and defects of different intraocular structures. Two kinds of malformations stand out as most typical--hypoplasia of the optic nervehead (up to 48%) and increased tortuosity of the retinal vessels, especially of the arteries (up to 49%). Visual acuity is often moderately or severely reduced. Considering the developmental timing of different tissues of the eye, one can presume that there is a risk for deleterious effects of alcohol on eye structures at any point of time from early gestation until development is completed.

Adolescent↗
PubMed1997

Vascular changes in retinas of spontaneously hypertensive rats demonstrated by corrosion casts.

The changes in the capillary network of the retina in spontaneously hypertensive rats (SHR) were demonstrated by scanning and transmission electron microscopy. Corrosion casts with scanning electron microscopy provided a three-dimensional view of the microvasculature of the rat retina and could detect the conspicuous features of the retinal vasculature in SHR. In general, when hypertension lasted for 6-7 months in SHR, tortuosity of the retinal vessels was noted, and later the SHR retina showed increased tortuosity and generalized narrowing of the vessels, localized constriction of the veins, arteriovenous crossing defects, and marked capillary changes, such as caliber irregularity, narrowing, bead-like capillaries, loop formation and localized obliteration. At a later stage, when the blood pressure had been sustained for a long time, there was marked capillary constriction which first affected the superficial capillary network, then scattered capillary network constriction and finally capillary dropout. Transmission electron microscopy revealed narrow capillary lumina and thin endothelium with scarce cytoplasmic components and damaged pericytes. These morphological changes in the capillary network were probably due to structural damage to the endothelial cells, facilitated possibly by compression of the precapillary arterioles. The severity of these changes was usually proportional to the degree and duration of hypertension. These findings indicate that the retinal capillary changes are probably related to hypertension.

Animals↗
PubMed1991

Electron-microscopic identification of pseudoexfoliation material in extrabulbar tissue.

The structure and distribution of pseudoexfoliation material in extrabulbar tissues from five eyes with typical unilateral intraocular pseudoexfoliation syndrome and two intraocularly unaffected fellow eyes were examined by transmission electron microscopy. In all seven eyes, unevenly distributed pseudoexfoliation aggregates were found in limbal conjunctivae, extraocular rectus and oblique muscles, orbital connective-tissue septa, and the walls of the posterior ciliary arteries, vortex veins, and central retinal vessels passing through the optic nerve sheaths. Typical pseudoexfoliation fibers occurred in close association with connective-tissue components, especially elastic fibers; a moderate predisposition of pseudoexfoliation clumps to accumulate around blood vessels was observed. The findings of pseudoexfoliation material in similar extrabulbar locations in intraocularly uninvolved fellow eyes indicates that pseudoexfoliation fiber formation outside the globe precedes its intraocular manifestation. The intermingling of pseudoexfoliation fibers, microfibrils, and elastic and collagen fibers suggests that pseudoexfoliation fiber formation might result from a disordered synthesis and/or assembly of connective-tissue microfibrils.

Aged↗
PubMed1989

Retinal dopamine sensitivity to MPP+ toxicity: electrophysiological and biochemical evaluation.

This study concerns the effect of intravitreal injection of 1-methyl-4-phenylpyridinium ion (MPP+) on the electroretinograms (ERG) and on the levels of retinal dopamine (DA) in rabbits. The right eye was injected intravitreously with MPP+ while the other received only the vehicle and served as control. The administration of 7, 40, 70 or 700 micrograms MPP+ resulted in a dose-related decrease of the amplitude of the a and b-waves as well as the oscillatory potentials (OPs) of the ERG, down to extinction. In contrast, the retinal DA content was decreased only with the 700 micrograms MPP+ dose. Fluorescein angiography demonstrated abnormalities in the retinal circulation of all MPP+-treated eyes. These observations indicate that MPP+ causes lesions to the retinal vessels at doses non-toxic to the retinal dopaminergic neurons. These data suggest that intravitreal injection of MPP+ cannot be used to study the physiological role of retinal DA.

1-Methyl-4-phenylpyridinium↗