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Biomedical subjects

J Flammer

Publications and source records attributed to J Flammer.

At least 37 records · Page 2Linked to original sources
PubMed2004

Ocular blood flow alteration in glaucoma is related to systemic vascular dysregulation.

AIMS: To investigate the source of ocular blood flow alterations in glaucoma. METHODS: In 56 patients with open angle glaucoma, blood flow parameters were obtained from both eyes in the ophthalmic and central retinal artery by means of colour Doppler imaging, as well as in the choroidal circulation and the neuroretinal rim of the optic nerve by means of laser Doppler flowmetry. Based on these haemodynamic parameters, a cluster analysis (two groups) was performed and differences with regard to risk factors were assessed between clusters. RESULTS: Ocular blood flow data in the two clusters indicated that the two groups (cluster 1 = 26 patient with higher blood flow values; cluster 2 = 30 patients with lower blood flow values) differed mainly in choroidal and optic nerve blood flow. No differences in sex distribution, propensity to have normal tension glaucoma, age, endothelin-1 plasma levels, visual field damage, intraocular pressure, or systemic blood pressure parameters were observed between the two clusters. However, 12 patients (46%) from the cluster with high ocular blood flow values showed a vasospastic response in nailfold capillaroscopy, while such a response was observed in 24 patients (80%) of the cluster with low ocular blood flow values. This difference in vasospastic propensity was statistically significant (p = 0.0121). CONCLUSIONS: Ocular blood flow alterations in glaucoma patients seem, at least partly, to be related to a systemic vascular dysregulation.

Aged↗
PubMed2004

Influence of non-penetrating glaucoma surgery on aqueous outflow facility in isolated porcine eyes.

PURPOSE: To investigate, in vitro, the influence of non-penetrating glaucoma surgery (NPGS) and the influence of tightly suturing the superficial scleral flap on the aqueous outflow facility of isolated porcine eyes. MATERIALS AND METHODS: The anterior chambers of 12 enucleated porcine cadaver eyes were cannulated and perfused. NPGS was performed by the same surgeon. The overall ocular aqueous outflow facilities were assessed before and after the surgical interventions of NPGS, as well as after scleral flap closure. RESULTS: The mean (SD) aqueous outflow facility, which was 0.164 (0.014) microl/min/mm Hg before surgery, increased significantly after NPGS to 1.584 (0.217) microl/min/mm Hg, p<0.001. When the superficial flap was closed, the aqueous outflow facility significantly decreased (0.754 (0.107) microl/min/mm Hg, p<0.001) but remained significantly higher than preoperatively (p<0.01). After suturing the superficial flap, the overall resistance increased to 1.625 (0.210) microl/min/mm Hg. The difference in the resistance to outflow before and after flap closure was 0.848 (0.169) microl/min/mm Hg. CONCLUSION: After NPGS suturing the scleral flap can modulate aqueous outflow resistance. The experimental set up described might provide an efficient model for the technical training of glaucoma surgeries.

Animals↗
PubMed2003

Architecture of arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve: anatomy and clinical considerations.

AIMS: To describe the anatomy and the arrangement of the arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve and to consider their possible clinical relevance for cerebrospinal fluid dynamics and fluid pressure in the subarachnoid space of the human optic nerve. METHODS: Postmortem study with a total of 12 optic nerves harvested from nine subjects without ocular disease. All optic nerves used in this study were obtained no later than 7 hours after death, following qualified consent for necropsy. The study was performed with transmission (TEM) and scanning electron microscopy (SEM). RESULTS: The subarachnoid space of the human optic nerve contains a variety of trabeculae, septa, and stout pillars that are arranged between the arachnoid and the pia layers of the meninges of the nerve. They display a considerable numeric and structural variability depending on their location within the different portions of the optic nerve. In the bulbar segment (ampulla), adjacent to the globe, a dense and highly ramified meshwork of delicate trabeculae is arranged in a reticular fashion. Between the arachnoid trabeculae, interconnecting velum-like processes are observed. In the mid-orbital segment of the orbital portion, the subarachnoid space is subdivided, and can appear even loosely chambered by broad trabeculae and velum-like septa at some locations. In the intracanalicular segment additionally, few stout pillars and single round trabeculae are observed. CONCLUSION: The subarachnoid space of the human optic nerve is not a homogeneous and anatomically empty chamber filled with cerebrospinal fluid, but it contains a complex system of arachnoid trabeculae and septa that divide the subarachnoid space. The trabeculae, septa, and pillars, as well as their arrangement described in this study, may have a role in the cerebrospinal fluid dynamics between the subarachnoid space of the optic nerve and the chiasmal cistern and may contribute to the understanding of the pathophysiology of asymmetric and unilateral papilloedema. All the structures described are of such delicate character that they can not even be visualised with high resolution magnetic resonance imaging (MRI).

Arachnoid↗
PubMed2003

Peripheral vasospasm and nocturnal blood pressure dipping--two distinct risk factors for glaucomatous damage?

PURPOSE: To evaluate the relationship between peripheral vasospasm and circadian blood pressure rhythm in patients with primary open angle glaucoma (POAG). METHODS: Nail-fold capillaroscopy, combined with a cold provocation test, and 24-hour blood pressure monitoring was carried out in 130 patients with POAG (M:F 58:72; mean age 60 +/- 14 years), 99 with high-tension glaucoma (HTG) and 31 with normal-tension glaucoma (NTG). Peripheral blood flow parameters were compared for patients with a nocturnal fall in mean systemic blood pressure (MBP) of less than 10% (non-dippers), patients with a nighttime MBP fall of 10-20% (dippers), and patients with a nighttime MBP fall of more than 20% (over-dippers). RESULTS: Patients with POAG showed a significantly lower blood flow velocity both at baseline (p < 0.01) and after cold provocation (p < 0.02) and a significantly higher percentage of cold-induced blood-flow standstill (p < 0.0001) in the nail-fold capillaroscopy than normal controls. The numbers of non-dippers (50), dippers (66) and over-dippers (14) did not differ between the HTG and NTG group. There were no significant differences between non-dippers, dippers, and over-dippers in peripheral blood flow parameters. CONCLUSIONS: Our findings indicate that vasospasm and low blood pressure may be distinct risk factors for glaucomatous damage. It also appears that screening for vascular dysregulation and systemic hypotension should not be restricted to NTG patients alone.

Blood Flow Velocity↗
PubMed2003

Iris transillumination defects in patients with primary open angle glaucoma.

PURPOSE: To examine the incidence and pattern of iris transillumination defects in patients with primary open angle glaucoma (POAG) with and without vascular dysregulation, in comparison to controls. METHODS: We prospectively examined 24 patients with POAG (M/F 10:14; mean age 59 +/- 14, range 21-76 years) and 23 controls (M/F 10:13; mean age 52 +/- 15, range 25-86 years). Vascular dysregulation was presumed if patients had a typical medical history of vasospasm and a pathological result in nailfold capillaroscopy. Iris transillumination defects were visualized by video-taped, digitized diaphanoscopy and assessed by two blinded observers. RESULTS: We found significantly more iris transillumination defects in POAG than in controls (54.2% vs. 8.7%; chi2 = 8.85; df = 1; p = 0.002). The defects in POAG showed a characteristic radially-streaked pattern different from those described, for instance, in pigment dispersion syndrome, pseudoexfoliation syndrome, and acute glaucoma. Glaucoma patients with vascular dysregulation had a tendency to a higher incidence of transillumination defects than non-vasospastic patients, though this finding was not significant. CONCLUSIONS: Patients with POAG have a higher incidence of iris transillumination defects than controls. The underlying mechanisms are not yet clear and call for further investigation.

Adult↗
PubMed2002

Molecular imaging of perfusion disturbances in glaucoma.

Ocular ischemia resulting from perfusion disturbances may play a major role in initiation of glaucoma. Possibly secondary to ischemia autoimmunogenic events are activated in glaucoma patients with increased prevalence of systemic autoimmune diseases. The determination of potential molecular markers in blood leukocytes could be useful for early noninvasive diagnostics of glaucoma. Our study using subtractive hybridization showed altered gene expression in leukocytes of glaucoma patients in comparison to age and sex matched healthy subjects. Subtracted genes encoding lymphocyte IgE receptor (Fc epsilon RII/CD23), T cell-specific tyrosine kinase, thromboxan A2 receptor, alkaline phosphatase and Na(+)/K(+)-ATPase are differentially expressed in circulating leukocytes of glaucoma patients. These genes show expression profiles characteristic for adherent leukocytes which could be an important contributor to blood-brain barrier breakdown which has been found in glaucoma patients.

Adult↗
PubMed2002

Melatonin MT-1-receptor immunoreactivity in the human eye.

AIM: To examine the distribution of melatonin 1a (MT1) receptors in the human eye. METHODS: Seven normal human eyes were examined by immunohistochemical staining of paraffin sections, using an anti-MT1 primary antibody and an ABC detection system. RESULTS: MT1 receptor immunoreactivity (MT1-IR) was detected primarily in the inner segments of rods and cones and in retinal ganglion cells. In addition, MT1-IR was present in the adventitia of retinal arteries and veins, including the papillary region, but absent in ciliary and choroidal vessels. Mild staining of corneal endothelial cells and keratocytes was observed in all but two eyes. CONCLUSION: MT1-IR is present in various ocular tissues with the highest density in photoreceptor cells and ganglion cells. The physiological function of these receptors deserves further investigation.

Aged↗
PubMed2001

Cold feet and prolonged sleep-onset latency in vasospastic syndrome.

People with vasospastic syndrome have cold hands and feet and abnormal vasoconstriction after local cold exposure. Normally there is a circadian rhythm of distal vasodilation, with onset in the early evening, which directly influences ability to fall asleep. We gave a sleep questionnaire to 32 patients with primary vasospastic syndrome and 31 healthy controls. People with vasospasticity had significantly prolonged sleep-onset latency both at onset of night-time sleep and after nocturnal disturbance. This prolonged latency could be associated with impaired capacity for distal vasodilation.

Adult↗
PubMed2001

An evaluation of the effect of unoprostone isopropyl 0.15% on ocular hemodynamics in normal-tension glaucoma patients.

BACKGROUND: Because intraocular pressure-lowering agents should have a good safety profile with regard to ocular hemodynamics, the innocuousness of unoprostone isopropyl 0.15% with regard to ocular hemodynamics in vasospastic patients with normal-tension glaucoma was assessed in a pilot study. METHODS: Corneal temperature as a parameter of ocular blood flow and choroidal and optic nerve blood flow as assessed by means of laser Doppler flowmetry techniques were evaluated in 12 vasospastic normal-tension glaucoma patients in a prospective, randomized, observer-masked, two-period crossover, placebo-controlled pilot trial. RESULTS: Statistical analysis in 2 x 2 two-way analysis of variance models with two treatments (placebo and unoprostone isopropyl) and two assessments (baseline and after 1 week of treatment) as within-subject factors disclosed a lack of difference between eyes, between the treatment (placebo/unoprostone isopropyl) periods, and between baseline and after 1 week of treatment in corneal temperature, choroidal blood flow, and optic nerve blood flow. The differences between the results at baseline and after 1 week of treatment in these parameters were not significantly different between the placebo treatment period and the unoprostone isopropyl treatment period, and this was comparable in fellow eyes for all the parameters. CONCLUSION: Unoprostone isopropyl did not induce any alterations in ocular hemodynamics in this pilot study with vasospastic normal-tension glaucoma patients.

Antihypertensive Agents↗
PubMed2001

Leber's hereditary optic neuropathy mitochondrial DNA mutations in normal-tension glaucoma.

BACKGROUND: in Leber's hereditary optic neuropathy, increased optic nerve cupping has been reported by several authors. Recently, a mitochondrial DNA (mtDNA) mutation at nucleotide 11778 typically associated with Leber's hereditary optic neuropathy (LHON) was identified in a patient treated for glaucoma but lacking typical signs of LHON. The question arises: should all normal-tension glaucoma patients be further evaluated for LHON? METHODS: we screened 54 unselected patients with normal-tension glaucoma (age range 20-96 years, 16 men and 38 women) for the primary mtDNA LHON mutations at nucleotides 3460, 11778 and 14484. RESULTS: none of the patients harboured the mtDNA mutations at nucleotides 3460, 11778 or 14484 (95% confidence intervals for each mutation ranged from 0% to 5.3%). CONCLUSIONS: primary LHON mtDNA mutations are rare or absent in unselected normal-tension glaucoma patients. Therefore, unselected normal-tension glaucoma patients should not be screened for these mutations. It is probable that only normal-tension glaucoma patients with atypical features (rapid progression, early deep central scotoma, pallor of neuroretinal rim, elevated disc, peripapillary teleangiectasia) or a positive family history of visual loss compatible with a matrilinear transmission should be further evaluated.

Adult↗
PubMed2001

Acute asymmetric upper nasal quandrantanopsia caused by a chiasmal colloid cyst in a patient with multiple sclerosis and bilateral retrobulbar neuritis.

PURPOSE: To report a patient with multiple sclerosis and a history of sequential bilateral retrobulbar neuritis, who developed new onset of highly asymmetric upper quadrantanopsia. DESIGN: Interventional case report. METHOD: A 36-year-old woman with multiple sclerosis and bilateral retrobulbar neuritis developed an acute asymmetric upper nasal quadrantanopsia. RESULTS: Magnetic resonance imaging of the brain revealed a cyst that caused chiasmal compression and bilateral visual field defects. CONCLUSION: New onset of bilateral visual field defects in a patient with diagnosed multiple sclerosis is likely to be caused by a new attack of the demyelinating disease. In this case, a newly diagnosed chiasmal colloid cyst was the cause of visual field defects.

Acute Disease↗
PubMed2001

Unilateral papilledema caused by a fronto-temporo-parietal arachnoid cyst.

PURPOSE: To report a case of unilateral papilledema caused by an arachnoid cyst. METHODS: Interventional case report. RESULTS: A 36-year-old woman presented with unilateral papilledema in the left eye. Magnetic resonance imaging (MRI) of the brain demonstrated a large fronto-temporo-parietal arachnoid cyst in the left hemisphere. The papilledema resolved after placement of a cysto-peritoneal shunt that drained the cerebrospinal fluid directly from the arachnoid cyst into the peritoneum. CONCLUSION: Papilledema caused by increased intracranial pressure is usually bilateral; unilateral papilledema is possible under special anatomical circumstances.

Adult↗
PubMed2001

Retrobulbar blood flow in glaucoma patients with nocturnal over-dipping in systemic blood pressure.

PURPOSE: To evaluate the relationship between the circadian blood pressure rhythm and the retrobulbar blood flow in glaucoma patients. DESIGN: Cross-sectional study. METHODS: Circadian blood pressure measurements and color Doppler imaging (CDI) in the ophthalmic artery as well as the central retinal artery of one randomly selected eye were obtained in 193 primary open-angle glaucoma patients. CDI parameters were compared by means of analysis of covariance between patients with a nocturnal decrease in mean systemic blood pressure (MBP) below 20% of the average daytime MBP (over-dippers), patients with a decrease between 10% to 20% (dippers), and patients with a decrease of less than 10% (nondippers), using age, intraocular pressure (IOP), and MBP during color Doppler measurement as covariates. RESULTS: An analysis of covariance disclosed, after correcting for age, IOP, and MBP during color Doppler imaging, a significantly lower EDV (P =.0096) and a significantly higher RI (P =.033) in the central artery of over-dipping glaucoma patients compared with nondippers or dippers. This effect seemed independent of the use of vasoactive drugs . CONCLUSIONS: Glaucoma patients with a marked drop in nocturnal systemic blood pressure seem to have altered retrobulbar blood flow parameters, suggesting that an abnormal systemic blood pressure profile may be the manifestation of some kind of systemic vascular dysregulation relevant for the ocular circulation.

Adrenergic beta-Antagonists↗
PubMed2001

Endothelium-dependent vasoactive modulation in the ophthalmic circulation.

The vascular endothelium is strategically located between the circulating blood and the vascular smooth muscle cells. Different agonists or stimuli transported by the circulating blood can trigger the endothelium to release potent relaxing (nitric oxide, prostacyclin, endothelium-derived hyperpolarizing factor) or contracting factors (endothelin, cycloxygenase products). These endothelium-derived vasoactive factors can modulate blood flow locally. Heterogeneity exists from one vascular bed to the other, or even between vessels, in the agonists able to stimulate the release of endothelium-derived vasoactive factors. In the ophthalmic circulation, nitric oxide and endothelin are strong vasoactive modulators. In many vascular diseases that are of importance in ophthalmology (hypercholesterolemia, arteriosclerosis, hypertension, diabetes, vasospastic syndrome, ischemia and reperfusion, etc) the function of the endothelium can be impaired. There exist different drugs that can modulate the vasoactive function of the vascular endothelium. In other words, it appears that the vascular endothelium plays an important role in both the physiology and pathophysiology of the regulation of blood flow. The modulation of this regulatory system by different drugs might open new therapeutical approaches to treat vascular disorders in ophthalmology.

Animals↗