Optic nerve oxygen tension: effects of intraocular pressure and dorzolamide

Cour, Morten la; Kiilgaard, Jens Folke; Eysteinsson, Þór; Wiencke, Anne Katrine; Bang, K; Dollerup, Jens; Jensen, Patricia; Stefánsson, Einar

doi:10.1136/bjo.84.9.1045

Cited by 42 publications

(35 citation statements)

References 16 publications

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“…23 Dorzolamide could have a positive effect on retinal and peripapillary haemodynamics owing to its ability to induce local metabolic acidosis and consequently relax arteriolar pericytes. 26,27 Evidence in literature on the effects of dorzolamide on OBF is contrasting. In normal eyes, it improved central visual function during hyper-and hypocapnia conditions.…”

Section: Introductionmentioning

confidence: 99%

The effects of dorzolamide 2% and dorzolamide/timolol fixed combination on retinal and optic nerve head blood flow in primary open-angle glaucoma patients

Rolle

Tofani

Brogliatti

et al. 2008

Eye

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Purpose To compare the effect of dorzolamide hydrochloride 2%, timolol maleate 0.5%, and their fixed combination on intraocular pressure (IOP) and retinal and optic nerve head haemodynamics in primary open-angle glaucoma patients. Methods Twenty-eight patients with early-moderate glaucomatous damage treated with b-blockers (46 months) with IOP values ranging from 18 to 22 mmHg at trough participated in this trial. After a 4-week washout period, patients were randomized in two groups: group I started with dorzolamide 2% monotherapy and group II with timolol 0.50% monotherapy for 4 weeks. After this period, both groups switched to dorzolamide/ timolol fixed combination for 4 weeks. IOP, ocular diastolic perfusion pressure (ODPP), heart rate, and Scanning Laser Doppler Flowmetry measurements at the peripapillary retina and neuroretinal rim were taken at T0 (enrolment), T1 (wash out), T2 (monotherapy), and T3 (dorzolamide/timolol). Data were compared between different study times. Statistical analysis was conducted using a paired t-test. Results Between T1 and T3, IOP decreased significantly in group I (À21.40%) (Po0.001) and in group II (À21.25%) (Po0.001). At the same time intervals, blood flow increased significantly at rim level for group I ( þ 30.03%) (Po0.05) and also when all patients were considered (rim þ 17.99%) (Po0.05). Between T1 and T3, we also observed a significant increase of ODPP in group I ( þ 7.24%) (Po0.01) and in group II ( þ 6.08%) (Po0.05) and when all patients were considered ( þ 8.43%) (Po0.01). Conclusions Dorzolamide/timolol fixed combination increased blood flow significantly at the neuroretinal rim showing a combination of hypotensive and haemodynamic effects.

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Section: Introductionmentioning

confidence: 99%

The effects of dorzolamide 2% and dorzolamide/timolol fixed combination on retinal and optic nerve head blood flow in primary open-angle glaucoma patients

Rolle

Tofani

Brogliatti

et al. 2008

Eye

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“…While there is no literature to date that measured human ONH oxygen concentrations in vivo, our range of values is consistent with that observed in mice and porcine models. 40,41 The absolute velocity values obtained from our simulations also expand our knowledge of ocular blood flow in the human LC, because conventional techniques (e.g., laser speckle flowgraphy) yield only relative velocities and cannot provide deep flow measurements within the LC. 42 Lamina cribosa diameter was found to be the most influential parameter affecting both oxygen concentration and hemodynamics.…”

Section: Discussionmentioning

confidence: 98%

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Chuangsuwanich

Birgersson

Thiéry

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To identify and rank the lamina cribrosa (LC) morphologic factors that influence LC microcapillary hemodynamics and oxygen concentrations using computational fluid dynamics (CFD).METHODS. We generated 12,000 'artificial' LC microcapillary networks and predicted blood flow velocities and oxygen concentrations within the microcapillaries using CFD. Across models, we varied the average pore size of the LC (5500 6 2400 lm 2 ), the microcapillary arrangement (radial, isotropic, or circumferential), the LC diameter (1.9 6 0.3 mm), the inferior-superior curvature (340 6 116 m À1 ), and the nasal-temporal curvature (À78 6 130 m À1 ). We assumed that blood flow originated from the Circle of Zinn-Haller, fed the LC uniformly at its periphery, and was drained into the central retinal vein. Arterial (50 6 6 mm Hg) and venous (17.7 6 6 mm Hg) pressures were applied as boundary conditions and were also varied within our simulations. Finally, we performed linear regression analysis to rank the influence of each factor on LC hemodynamics and oxygen concentrations. RESULTS.The factors influencing LC hemodynamics and oxygen concentrations the most were: LC diameter, arterial pressure, and venous pressure, and to a lesser extent: the microcapillary arrangement (anisotropy) and nasal-temporal curvature. Lamina cribrosa pore size and superior-inferior curvature had almost no impact. Specifically, we found that LCs with a smaller diameter, a radial arrangement of the microcapillaries, an elevated arterial pressure and a decreased venous pressure had higher oxygen concentrations across their networks.CONCLUSION. This study described LC hemodynamics using a computational modeling approach. Our study may provide clinically relevant information for the understanding of ischemia-induced neuronal cell death in optic neuropathies.

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“…Measurements of oxygen tension overlying the optic nerve and retina have been reported in numerous animal studies; [5][6][7][8][9] however, the technique involves the intraocular insertion of microelectrodes which is technically demanding and invasive. Phosphorescence imaging has been performed in experimental glaucoma in animals, 10,11 but requires the injection of a bolus of an oxygen chemical probe whose safety in humans has yet to be determined.…”

Section: Introductionmentioning

confidence: 99%

Oxygen saturation measurements of the retinal vasculature in treated asymmetrical primary open-angle glaucoma using hyperspectral imaging

Mordant

Alabboud

Muyo

et al. 2014

Eye

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Purpose To determine whether there are differences in retinal vascular oxygen saturation measurements, estimated using a hyperspectral fundus camera, between normal eyes and treated eyes of subjects with asymmetrical primary open-angle glaucoma (POAG). Methods A noninvasive hyperspectral fundus camera was used to acquire spectral images of the retina at wavelengths between 556 and 650 nm in 2-nm increments. In total, 14 normal eyes and both eyes of 11 treated POAG subjects were imaged and analyzed using algorithms that use the spectral variation of the optical densities of blood vessels to estimate the oxygen saturation of blood within the retinal vasculature. In the treated POAG group, each of the eyes were categorized, based on the mean deviation of the Humphrey visual-field analyzer result, as either more-advanced or less-advanced, glaucomatous eyes. Unpaired t-tests (twotailed) with Welch's correction were used to compare the mean oxygen saturation between the normal subjects and the treated POAG subgroups. Results In less-advanced and moreadvanced-treated POAG eyes, mean retinal venular oxygen saturations (48.2 ± 21.6% and 42.6 ± 18.8%, respectively) were significantly higher than in normal eyes (27.9 ± 9.9%; P ¼ 0.03 and 0.01, respectively). Arteriolar oxygen saturation was not significantly different between normal eyes and treated POAG eyes. ConclusionsThe increased oxygen saturation of the retinal venules in advancedtreated POAG eyes may indicate reduced metabolic consumption of oxygen in the inner retinal tissues.

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Optic nerve oxygen tension: effects of intraocular pressure and dorzolamide

Cited by 42 publications

References 16 publications

The effects of dorzolamide 2% and dorzolamide/timolol fixed combination on retinal and optic nerve head blood flow in primary open-angle glaucoma patients

The effects of dorzolamide 2% and dorzolamide/timolol fixed combination on retinal and optic nerve head blood flow in primary open-angle glaucoma patients

Factors Influencing Lamina Cribrosa Microcapillary Hemodynamics and Oxygen Concentrations

Oxygen saturation measurements of the retinal vasculature in treated asymmetrical primary open-angle glaucoma using hyperspectral imaging

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