Optic nerve head blood flow regulation during changes in arterial blood pressure in patients with primary open‐angle glaucoma

Bata, Ahmed M.; Fondi, Klemens; Witkowska, K.; Werkmeister, René M.; Hommer, Anton; Vass, Clemens; Resch, Hemma; Schmidl, Doreen; Popa-Cherecheanu, Alina; Chua, Jacqueline; Garhöfer, Gerhard; Schmetterer, Leopold

doi:10.1111/aos.13850

Cited by 27 publications

(19 citation statements)

References 46 publications

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“…This is in agreement with previous results indicating the presence of blood flow autoregulation in the ONH . In patients with glaucoma, the response of ocular blood flow to isometric exercise has been consistently found to be altered during isometric exercise . Whether dronabinol would normalize this abnormal autoregulatory response in glaucoma is still to be investigated.…”

Section: Discussionsupporting

confidence: 92%

The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects—A Randomized Clinical Trial

Hommer

Kallab

Szegedi

et al. 2020

Clin Pharma and Therapeutics

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It has been hypothesized that besides its intraocular pressure (IOP) lowering potential, tetrahydrocannabinol (THC) may also improve ocular hemodynamics. The aim of the present study was to investigate whether single oral administration of dronabinol, a synthetic THC, alters optic nerve head blood flow (ONHBF) and its regulation in healthy subjects. The study was carried out in a randomized, placebo‐controlled, double‐masked, two‐way crossover design in 24 healthy subjects. For each study participant, 2 study days were scheduled, on which they either received capsules containing 5 mg dronabinol or placebo. ONHBF was measured with laser Doppler flowmetry at rest and while the study participants performed isometric exercise for 6 minutes to increase mean arterial blood pressure (MAP). This was repeated 1 hour after drug intake. Ocular perfusion pressure (OPP) was calculated as 2/3MAP–IOP. Dronabinol was well tolerated and no cannabinoid‐related psychoactive effects were reported. Neither administration of dronabinol nor placebo had an effect on IOP, MAP, or OPP. In contrast, dronabinol significantly increased ONHBF at rest by 9.5 ± 8.1%, whereas placebo did not show a change in ONHBF (0.3 ± 7.4% vs. baseline, P < 0.001 between study days). Dronabinol did not alter the autoregulatory response of ONHBF to isometric exercise. In conclusion, the present data indicate that low‐dose dronabinol increases ONHBF in healthy subjects without affecting IOP, OPP, or inducing psychoactive side effects. In addition, dronabinol does not alter the autoregulatory response of ONHBF to an experimental increase in OPP. Further studies are needed to investigate whether this effect can also be observed in patients with glaucoma.

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Section: Discussionsupporting

confidence: 92%

The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects—A Randomized Clinical Trial

Hommer

Kallab

Szegedi

et al. 2020

Clin Pharma and Therapeutics

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“…In addition, given that VD is a validated value determined automatically by a device which calculates the total area investigated/the area occupied by vessels based on retina’s en face imaging, the present study yielded some additional evidence that retinal vessels are influenced by an autoregulatory system in order to maintain stable vascularity that is independent of other factors 28,29. Conversely, a number of previous studies indicated abnormal ocular blood flow autoregulation in glaucoma using different technologies such as color/laser Doppler flowmetry 30,31. However, it should be noted that OCTA can quantitively assess vessel calibre volume in the area investigated, but not the amount of blood flow.…”

Section: Discussionsupporting

confidence: 49%

<p>Diurnal Stability Of Peripapillary Vessel Density And Nerve Fiber Layer Thickness On Optical Coherence Tomography Angiography In Healthy, Ocular Hypertension And Glaucoma Eyes</p>

Bochicchio¹,

Milani²,

Urbini³

et al. 2019

OPTH

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PurposeBy using optical coherence tomography angiography (OCTA), to evaluate diurnal changes of the following parameters: vessel density in the peripapillary area (PP-VD) and in the optic nerve head (ONH-VD); thickness of retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC).MethodsAll prospectively enrolled participants were imaged on the same day at 8 am and 7 pm by means of the XR Avanti device with AngioVue and AngioAnalytics software (Optovue Inc., Fremont, CA, USA). Only eyes with correct automatic segmentation and good-quality images (scan quality > 7/10) were included.ResultsForty-six eyes from 28 patients with glaucoma, 53 from 31 patients with ocular hypertension, and 62 from 38 controls were assessed. The mean measurements of all parameters investigated were significantly different in the morning and in the evening values in all three groups, with lower values in glaucomatous eyes (p<0.014). In control eyes, as well as in eyes of patients with ocular hypertension and glaucoma the daily changes were minimal and not statistically significant with means of +0.17%, −0.31% and −0.54% for ONH-VD (p=0.83) and means of +0.2%, +0.1% and +0.29% for PP-VD (p=0.83), respectively. Likewise, daily fluctuations in GCC and RNFL thickness were not significant in any of the three groups, with means of +0.16 µm, +0.66 µm and −0.15 µm for GCC (p=0.58) and means of +0.24 µm, +0.58 µm and −0.24 µm for ONH-RNFL (p=0.90), respectively. Systemic hypertension, age, axial length, daily changes in intraocular pressure or scan quality did not correlate with daily fluctuations of any of the parameters investigated (p>0.1).ConclusionVessel density, GCC and RNFL were stable during daytime thus corroborating the clinical relevance of OCTA regardless the time of acquisition.

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“… 28 , 29 The retinal vasculature, although reduced in eyes with POAG and ocular hypertension, may be unaffected by diurnal circadian changes, at least to the extent that can be assessed using OCTA. In fact, abnormal autoregulation of ocular blood flow in glaucoma was evidenced using different technologies, such as color/laser Doppler flowmetry, 30 , 31 whereas OCTA can only assess quantitatively the vessel caliber volume, not the volume of blood flow. It must be acknowledged, however, that choroidal thickness varies during the day in healthy eyes, being increased in the morning, probably because of diurnal blood pressure variations.…”

Section: Discussionmentioning

confidence: 99%

The Macular Choriocapillaris Flow in Glaucoma and Within-Day Fluctuations: An Optical Coherence Tomography Angiography Study

Milani

Urbini

Bulone

et al. 2021

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To assess quantitatively the choriocapillaris (CC) perfusion area in the macular area of healthy eyes, eyes with primary open-angle glaucoma, and eyes with ocular hypertension using optical coherence tomography angiography (OCTA). METHODS.A consecutive series of healthy individuals and patients with glaucoma and ocular hypertension were recruited prospectively in this single-center, cross-sectional study based in Milan, Italy. OCTA was performed in the morning and evening, along with a complete ophthalmologic examination. Macular superficial capillary plexus vessel density (SCP-VD) and the thicknesses of the retina and ganglion cell complex (GCC), as well as their fluctuations, were investigated. RESULTS.Thirty-nine eyes from 24 individuals with glaucoma (mean age = 58.79 ± 6 years), 43 eyes from 27 individuals with ocular hypertension (59.19 ± 6 years), and 54 eyes from 35 controls (58.27 ± 6 years) were enrolled. The mean CC perfusion area values were not significantly different among the three groups in the morning or evening (P ≥ 0.47). In contrast, SCP-VD, retinal thickness, and GCC thickness were statistically different among the groups (P ≤ 0.016), except for the foveal SCP-VD (P ≥ 0.19) and the evening foveal thickness (P = 0.57). Diurnal changes in the CC perfusion area, SCP-VD, retinal thickness, and GCC thickness were not statistically significant (P ≥ 0.16). Systemic hypertension, sex, age, axial length, and diurnal changes in intraocular pressure were not significantly associated with morning or evening measurements, or with diurnal fluctuations (P ≥ 0.07). CONCLUSIONS.The macular CC flow perfusion area appears unaffected in eyes with primary open-angle glaucoma. No significant diurnal changes were observed in any of the parameters investigated.

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Optic nerve head blood flow regulation during changes in arterial blood pressure in patients with primary open‐angle glaucoma

Abstract: This study suggests that abnormal ONHBF autoregulation is more often seen in patients with POAG than healthy control subjects. The relationship to the glaucoma disease process is currently unknown and requires further investigation.

Cited by 27 publications

References 46 publications

The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects—A Randomized Clinical Trial

The Effect of Orally Administered Dronabinol on Optic Nerve Head Blood Flow in Healthy Subjects—A Randomized Clinical Trial

<p>Diurnal Stability Of Peripapillary Vessel Density And Nerve Fiber Layer Thickness On Optical Coherence Tomography Angiography In Healthy, Ocular Hypertension And Glaucoma Eyes</p>

The Macular Choriocapillaris Flow in Glaucoma and Within-Day Fluctuations: An Optical Coherence Tomography Angiography Study

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