Josef Flammer

Dynamics of retinal vessel response to flicker light in glaucoma patients and ocular hypertensives

PurposeTo analyze dynamics of retinal vessel dilation response to flicker light in patients with glaucoma and ocular hypertension.Patients and methodsResponse to flicker light was measured in retinal vessels by means of Retinal Vessel Analyzer. After the baseline 50xa0seconds long diameter recording of inferior and superior temporal artery and vein, three flicker stimulations of 20xa0seconds duration was applied, with a 80xa0seconds break in between. Area under the curve of the vessel diameter (AUC) was compared during 3 flicker periods in the open angle glaucoma patients group (POAG, nu2009=u200947) and ocular hypertensives (OHT, nu2009=u200946) and age-matched healthy controls (nu2009=u200956)ResultsPOAG eyes demonstrated smaller response of all vessels to flicker light in general than the other two groups (pu2009=u20090.0008), but the response dynamics was significantly different between the groups (pu2009=u20090.038), showing in three flicker periods a delayed increasing response in the POAG and OHT groups, and remaining stable in healthy subjects.ConclusionGeneral vessel response to flicker light was decreased in POAG patients despite the slow improvement in repeated flicker stimulation, indicating an altered response pattern.

Relationship between ocular pulse amplitude and systemic blood pressure measurements

Purpose:u2002 This study aimed to determine whether ocular pulse amplitude (OPA) measured with dynamic contour tonometry (DCT) is related to systemic blood pressure (BP) parameters.

Postoperative microhyphema as a positive prognostic indicator in canaloplasty.

Purpose:u2002 To assess risk factors for failure in canaloplasty.

Is the medication used to achieve the target intraocular pressure in glaucoma therapy of relevance? – An exemplary analysis on the basis of two beta-blockers

Glaucoma, the most common optic neuropathy (GON) is characterised by the loss of retinal ganglion cells and their axons, as well as tissue remodelling of both the retina and the optic nerve head with corresponding visual field defects. Elevated intraocular pressure (IOP) is generally regarded as the major risk factor for glaucoma and its reduction is the most common target for therapy of GON. There are indications that the greater the IOP reduction, the better is the visual field prognosis. This article investigates, on the basis of two beta-blockers, betaxolol and timolol, whether the amount of IOP reduction is truly a good surrogate for successful glaucoma therapy with respect to visual field outcome. Contrary to what is generally expected, our analysis of the literature exemplifies that despite a smaller IOP reduction, patients treated with betaxolol had a smaller rate of visual field deterioration than patients treated with timolol. Based on the dissociation of IOP reduction and visual field prognosis, we postulate that for successful treatment in glaucoma not only the amount of IOP reduction is relevant but also the drug by which the reduction is achieved. This seeming paradox phenomenon highlights that ocular hypotensive drugs have relevant effects on GON other than IOP-related. Some of these effects on retinal ganglion cells (neuroprotection) or on ocular blood flow are mediated by calcium- and sodium channels. Future studies on glaucoma treatment should focus on their effect on visual field function, and not just on IOP. This should particularly be considered when comparing drugs from different classes.

Retinal neurovascular coupling in patients with glaucoma and ocular hypertension and its association with the level of glaucomatous damage

PurposeTo analyze neurovascular coupling in the retina of untreated primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients.Patients and methodsMaximal vessel dilation in response to flicker light was analyzed with Retinal Vessel Analyzer (RVA) in temporal superior/inferior arterioles and veins in 51 POAG patients, 46 OHT and 59 control subjects. RVA parameters were compared between groups, between contralateral POAG eyes, and correlated to intraocular pressure, visual field mean defect and retinal nerve fiber layer thickness.ResultsPOAG eyes demonstrated generally smaller response of all vessels to flicker light than the other two groups (ANOVA pu2009=u20090.026; mean arterial flicker response in percent of baseline, averaged superior and inferior was 3.48u2009±u20092.22xa0% for controls , 2.35u2009±u20092.06 % for POAG patients , and 2.97u2009±u20092.35 % for OHT patients; corresponding values for venules were 3.88u2009±u20091.98xa0%, 2.89u2009±u20091.72xa0%, 3.45u2009±u20092.77xa0%). There was no difference in flicker response between the eye with more and less advanced damage in each patient of the POAG group (ANOVA pu2009=u20090.79). Correlation of flicker response to intraocular pressure (IOP) was borderline at best, correlations to the level of glaucomatous damage were not significant. Correlation of flicker response of superior and inferior vessels of the same eye was significant for the arteries (Pearson ru2009=u20090.23, pu2009=u20090.004), as well as venules (ru2009=u20090.52, pu2009<u20090.001).ConclusionGeneral vessel response to flicker light was decreased in POAG patients, compared to normal controls and OHT patients. In contrast to significant correlation between the two contralateral eyes of the flicker response itself, only its borderline correlation to IOP was seen. There was no correlation to the level of damage, altogether indicating a systemic dysregulation phenomenon.GrantsSwiss National Foundation Grant 3200B0-113685, Velux Stiftung Grant, Freie Akademische Gesellschaft (FAG) Grant, Pfizer Inc. GrantClinical trial registration reference numberClinicalTrials.gov NCT00430209

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

Abstract. 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 2×2 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.

Ocular blood flow and glaucomatous optic neuropathy

Ocular blood flow and glaucomatous optic neuropathy / , Ocular blood flow and glaucomatous optic neuropathy / , کتابخانه دیجیتال جندی شاپور اهواز

Basic Sciences in Ophthalmology

Basic sciences in ophthalmology : , Basic sciences in ophthalmology : , کتابخانه دیجیتال جندی شاپور اهواز

Age-corrected reference values for the Heidelberg multi-color anomaloscope

BackgroundTo determine reference values for the HMC anomaloscope (Heidelberg multi-color anomaloscope) of healthy subjects.MethodsOne hundred and thirteen healthy subjects were divided into four age groups: <20xa0years of age (ten female, five male), 20–39xa0years of age (23 female, 15 male), 40–59xa0years of age (23 female, ten male) andu2009>60xa0years of age (nine female, 18 male). Match midpoint, matching range (MR) and anomaly quotient (AQ), according to the Moreland equation [blue (436xa0nm) + blue–green (490xa0nm) = cyan (480xa0nm) + yellow (589xa0nm)] and according to the Rayleigh equation [green (546xa0nm) + red (671xa0nm) = yellow (589xa0nm)] were determined. The neutral adaptation was done showing white light every 5xa0seconds in absolute mode and every 15xa0seconds in relative mode.ResultsThe mean match midpoint according to the Rayleigh equation was 43.9u2009±u20092.6 scale units in absolute mode. It was highest between 20–39xa0years (45.2u2009±u20092.2) and lowest in subjects >60xa0years of age (42.2u2009±u20092.2). The mean MR in absolute mode was 3.1u2009±u20093.5 scale units with a maximum >60xa0years (4.4u2009±u20094.4). The MR in relative mode was between 1.6u2009±u20091.9 (20–39xa0years) and 4.4u2009±u20093.8 (>60xa0years). The resulting mean AQ was 1.01u2009±u20090.15 in both modes. The mean match midpoint of the Moreland equation was 51.0u2009±u20095.2 scale units in absolute mode. It was highest between 20–39xa0years (52.5u2009±u20095.7), and lowest in subjects >60xa0years of age (48.7u2009±u20093.6). The mean MR according to the Moreland equation was lower in absolute mode (13.4u2009±u200915.6) than in relative mode (16.2u2009±u200915.2). The mean resulting AQ was 1.02u2009±u20090.21 in both modes.ConclusionThe values of this study can be used as references for the diagnosis of red–green and blue perception impairment with the HMC anomaloscope.

The Mechanism of Glaucomatous Damage to the Optic Nerve

The pathogenesis of glaucomatous damage involves activation of astrocytes and involvement of oxidative stress in the mitochondria, which are located numerously in the axons of the optic nerve head (ONH). Astrocytes are activated by both mechanical and ischaemic stress. The major cause of oxidative stress is unstable blood flow, which is unstable if either intraocular pressure (IOP) fluctuates on a high level, exceeding the capacity for autoregulation from time to time, or if autoregulation by itself is disturbed. The main cause of disturbed autoregulation is primary vascular dysregulation syndrome. The simultaneous production of superoxide anions and nitric oxide leads to the damaging peroxinitrite, which induces apoptosis. Simultaneously, the entire microenvironment is changed, including an upregulation of matrix metalloproteinases (MMPs), contributing to tissue remodelling and thereby to excavation.