Functional Ophthalmodynamometry. Comparison Between Brachial and Ophthalmic Blood Pressure in Sitting and Supine Position

Sayegh, Fouad N.; Weigelin, E

doi:10.1177/000331978303400303

Cited by 27 publications

(16 citation statements)

References 3 publications

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“…10 The aggregate choroidal vasculature (represented herein as CT) has not been shown to have an intrinsic ability to regulate thickness/blood flow during positional changes 11 ; however, there may be situations by which a not-yet-identified mechanism increases choroidal blood flow when an eye is in a lower or supine position. 10,22,23 These findings would be consistent with our hypothesis for the changes in CCET with positioning that we found in healthy individuals. In the presence of such a responsive or autoregulatory mechanism, a drop in perfusion and choroidal blood flow might be anticipated in the supine position; however, what is observed is an increase in choroidal blood flow, which is consistent with hydrostatic intravascular changes.…”

Section: Discussionsupporting

confidence: 93%

Comparison of Retinal and Choriocapillaris Thicknesses Following Sitting to Supine Transition in Healthy Individuals and Patients With Age-Related Macular Degeneration

et al. 2015

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The effects of position on retinal and choroidal structure are absent from the literature yet may provide insights into disease states such as age-related macular degeneration (AMD).OBJECTIVE To evaluate the effect of postural change on retinal and choroidal structures in healthy volunteers and patients with non-neovascular AMD.DESIGN, SETTING, AND PARTICIPANTS Prospective observational case series at an academic tertiary care retina service from September 2013 to April 2014 involving 4 unaffected volunteers (8 eyes) and 7 patients (8 eyes) with intermediate AMD. Healthy volunteers selected for the study had no evidence of ocular disease. Patients with AMD were required to have at least 10 intermediate-sized drusen.EXPOSURES Spectral-domain optical coherence tomography with enhanced depth imaging in upright (sitting) and supine positions. Stable imaging was achieved using a rotating adjustable mechanical arm that we constructed to allow the optical coherence tomography transducer to rotate 90°. The Iowa Reference Algorithms were used to quantify choroid and choriocapillaris thicknesses. MAIN OUTCOMES AND MEASURESChanges in sitting and supine position central macular thickness (in micrometers), total macular volume (in cubic millimeters), choroidal thickness (in micrometers), and choriocapillaris-equivalent thickness (CCET, in micrometers).RESULTS Choriocapillaris-equivalent thickness was thinner in healthy participants (9.89 μm; range, 7.15-12.5 μm) compared with patients with intermediate AMD (16.73 μm; range, 10.31-27.38 μm) (P = .02); there was no difference in overall choroidal thickness between the 2 groups (P = .38). There was a 15% CCET reduction among healthy participants when transitioning from a sitting (9.89 μm) to supine (8.4 μm; range, 6.92-10.7 μm) position (P = .02) vs a CCET reduction of 11.1% from sitting (16.73 μm) to supine (14.88 μm; range, 8.76-20.8 μm) positioning (P = .10) in patients with intermediate AMD. CONCLUSIONS AND RELEVANCEIntermediate AMD appears to be associated with an increase in CCET and with a lack of positional responses that are observed in the CCET of normal eyes. Our results suggest that although outer portions of the choroid do not appear to be responsive to modest positional or hydrostatic pressure, the choriocapillaris capacity is, and this is measurable in vivo. Whether this physiologic deviation that occurs in AMD is related to atrophy, inflammation, or changes in autoregulatory factors or growth factors remains to be determined.

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Section: Discussionsupporting

confidence: 93%

Comparison of Retinal and Choriocapillaris Thicknesses Following Sitting to Supine Transition in Healthy Individuals and Patients With Age-Related Macular Degeneration

et al. 2015

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“…The mean arterial pressure (MAP) was calculated with the following formula: MAP=DBP +0.42 (SBP−DBP). [24][25][26] The ocular perfusion pressure (OPP) was calculated by subtracting the IOP from the two-third of the MAP. 27 Peripapillary and parafoveal perfusion measurements using OCT angiography OCT angiography scans were obtained by the spectral domain system RTVue-XR OCT (Optovue Inc, software V.2014.2.0.65).…”

Section: Materials and Methods Participantsmentioning

confidence: 99%

Is the peripapillary retinal perfusion related to myopia in healthy eyes? A prospective comparative study

Wang

Kong

Jiang³

et al. 2016

BMJ Open

131

112

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ObjectivesThe aim of this study was to evaluate the peripapillary and parafoveal perfusion of young, healthy myopic subjects with spectral domain optical coherence tomography (OCT) angiography.DesignA prospective comparative study was conducted from December 2014 to January 2015.SettingParticipants recruited from a population-based study performed by the Eye, Ear, Nose and Throat Hospital of Fudan University in Shanghai.ParticipantsA total of 78 Chinese normal subjects (78 eyes) with different refraction were included. Myopia was divided into 4 groups on the basis of the refractive status: 20 eyes with emmetropia (mean spherical equivalent (MSE) 0.50D to −0.50D), 20 eyes with mild myopia (MSE −0.75D to −2.75D), 20 eyes with moderate myopia (MSE −3.00D to −5.75D), and 18 eyes with high myopia (MSE≤−6.00D).Main outcome measuresPeripapillary and parafoveal retinal and choroidal perfusion parameters and their relationships with axial length (AL) and retinal nerve fibre layer (RNFL) thickness were analysed.ResultsSignificant differences were found for the retinal flow index and vessel density in the peripapillary area among the 4 groups, but not in the parafoveal area. The high myopia group had the lowest peripapillary retinal flow index and vessel density. In addition, there was a negative correlation (β=−0.002, p=0.047) between the AL and peripapillary retinal flow index and a positive correlation between RNFL thickness and the peripapillary retinal perfusion parameters (flow index: β=0.001, p=0.006; vessel density: β=0.350, p=0.002) even after adjustment for other variables.ConclusionsHighly myopic eyes have a decreased peripapillary retinal perfusion compared with emmetropic eyes. Such vascular features might increase the susceptibility to vascular-related eye diseases.

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“…40,41 Supine ocular perfusion pressure (OPP) was calculated as MOAP – IOP, where the mean ophthalmic arterial blood pressure (MOAP) = 0.84 • MAP in the supine position. 42,43 …”

Section: Methodsmentioning

confidence: 99%

Choroidal Blood Flow Decreases with Age: An MRI Study

Nateras

Harrison

Muir

et al. 2014

Current Eye Research

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Purpose To verify that a visual fixation protocol with cued eye blinks achieves sufficient stability for magnetic resonance imaging (MRI) blood-flow measurements and to determine if choroidal blood flow (ChBF) changes with age in humans. Methods The visual fixation stability achievable during an MRI scan was measured in five normal subjects using an eye-tracking camera outside the MRI scanner. Subjects were instructed to blink immediately after recorded MRI sound cues but to otherwise maintain stable visual fixation on a small target. Using this fixation protocol, ChBF was measured with MRI using a 3 Tesla clinical scanner in 17 normal subjects (24–68 years old). Arterial and intraocular pressures (IOP) were measured to calculate perfusion pressure in the same subjects. Results The mean temporal fluctuations (standard deviation) of the horizontal and vertical displacements were 29 ± 9 μm and 38 ± 11 μm within individual fixation periods, and 50 ± 34 μm and 48 ± 19 μm across different fixation periods. The absolute displacements were 67 ± 31 μm and 81 ± 26 μm. ChBF was negatively correlated with age (R =−0.7, p = 0.003), declining 2.7 ml/100 ml/min per year. There were no significant correlations between ChBF versus perfusion pressure, arterial pressure, or IOP. There were also no significant correlations between age versus perfusion pressure, arterial pressure, or IOP. Multiple regression analysis indicated that age was the only measured independent variable that was significantly correlated with ChBF (p = 0.03). Conclusions The visual fixation protocol with cued eye blinks was effective in achieving sufficient stability for MRI measurements. ChBF had a significant negative correlation with age.

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Functional Ophthalmodynamometry. Comparison Between Brachial and Ophthalmic Blood Pressure in Sitting and Supine Position

Cited by 27 publications

References 3 publications

Comparison of Retinal and Choriocapillaris Thicknesses Following Sitting to Supine Transition in Healthy Individuals and Patients With Age-Related Macular Degeneration

Comparison of Retinal and Choriocapillaris Thicknesses Following Sitting to Supine Transition in Healthy Individuals and Patients With Age-Related Macular Degeneration

Is the peripapillary retinal perfusion related to myopia in healthy eyes? A prospective comparative study

Choroidal Blood Flow Decreases with Age: An MRI Study

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