Mapping the surface astrocytes of the optic disc: a fluid‐conducting role of the astrocytic covering of the central vessels

Carreras, Francisco Javier; Porcel, David; Muñoz-Ávila, José Ignacio

doi:10.1111/j.1442-9071.2010.02206.x

Cited by 10 publications

(11 citation statements)

References 10 publications

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“…This new hypothesis, which is defended in the present study, should explain the loss of axons in conditions of high or low IOP and account for the initial or early damage of glaucoma in the ONH as a consequence of the deviation of the aqueous humor outlet during the development of glaucoma toward the posterior pole, in which there is protective role played by the blood vessel covering the underlying axons [3,9]. This new postulate would allow determining the pattern of visual field loss because the scotomas would be limited in their extent by the projection of the blood vessels in the visual field [9,11,12]. Being possible to carry out a detection as early as possible, through the techniques of perimetric and morphological data, to adopt the appropriate therapeutic measures.…”

Section: Introductionmentioning

confidence: 59%

“…This is due to the lack of an epithelial barrier on the anterior surface of the vitreous. When there is an increase in resistance in the regulation of the aqueous humor outflow normal pathway with an increase in IOP, these discontinuities or holes produce an increase in aqueous humor flow toward the posterior pole [9]. This process is supported by the existence of optic nerve head (ONH) permeability, since the nerve’s vitreous interface is formed by astrocytes, where fenestrations are described that allow the free passage of fluid and solutes from the vitreous to prelaminar tissue [10, 11].…”

Section: Introductionmentioning

confidence: 99%

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On the protective role of the blood vessels in glaucomatous damage: a transversal study

Cánovas-Serrano

Vallés-San-Leandro²,

Rodríguez-Izquierdo³

et al. 2021

Preprint

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Purpose: To corroborate whether vessels on the surface of the optic nerve head can provide protection against the loss of underlying axons in subjects with manifest glaucoma. Methods: In this pilot study, thirty-six glaucomatous eyes with a perimetric defect in the Bjerrum area were included. The retinal nerve fiber layer (RNFL) thickness was measured in each of the sectors of the clock-hour map obtained by Cirrus HD-OCT considering the presence or absence of blood vessels. These sectors were related with their corresponding areas of the retina examined in the visual field using a mathematical model of the retina introduced by Jansonius, in order to determine the values of threshold sensitivity in those areas in the presence or absence of vessels. Results: We corroborated the protective role of the blood vessel for peripapillary RNFL thickness of clock-hour 12 despite obtaining a p-value (p = 0.023; w = 228.5) close to the acceptance zone (p ≥ 0.05). The mean plus-or-minus sign standard deviation with vessel and without vessel were 70.95 plus-or-minus sign 24.35 and 88.46 plus-or-minus sign 23.96, respectively. No differences were found between the mean values of threshold sensitivity to the presence or absence of blood vessels in each of the sectors considered. Conclusions: Our findings do not allow us to affirm that there is an association between the presence of a vessel and protection against glaucomatous damage in subjects with an advanced manifestation of the disease. In the future, more extensive studies are needed to study this relationship in subjects with early glaucoma. Key words: astrocytes, visual field, primary open-angle glaucoma, aqueous humor, blood vessel.

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Section: Introductionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

On the protective role of the blood vessels in glaucomatous damage: a transversal study

Cánovas-Serrano

Vallés-San-Leandro²,

Rodríguez-Izquierdo³

et al. 2021

Preprint

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“…[ 45 ] This cell architecture of the prelaminar region enables the unimpeded passage of fluids from the vitreous cavity due to the complete absence of tight junctions, as has been shown by perfusing the vitreous at high physiological pressure. [ 46 , 47 ]…”

Section: Discussionmentioning

confidence: 99%

Expression of Glucose Transporters in the Prelaminar Region of the Optic-Nerve Head of the Pig as Determined by Immunolabeling and Tissue Culture

et al. 2015

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BackgroundTo develop the use of cultured tissue of the prelaminar optic nerve of the pig to explore possible alterations of the astrocyte-axon metabolic pathways in glaucoma, we map the distribution of the glucose transporters GLUT1 and GLUT3 in fresh and cultured tissue.MethodsWe monitor cell survival in cultures of the prelaminar optic-nerve tissue, measuring necrosis and apoptosis markers biochemically as well as morphologically, and establish the presence of the glucose transporters GLUT1 and GLUT3. We map the distribution of these transporters with immunolabeling in histological sections of the optic nerve using confocal and electronic transmission microscopy.ResultsWe find that the main death type in prelaminar culture is apoptosis. Caspase 7 staining reveals an increment in apoptosis from day 1 to day 4 and a reduction from day 4 to day 8. Western blotting for GLUT1 shows stability with increased culture time. CLSM micrographs locate GLUT1 in the columnar astrocytes and in the area of axonal bundles. Anti-GLUT3 predominantly labels axonal bundles. TEM immunolabeling with colloidal gold displays a very specific distribution of GLUT-1 in the membranes of vascular endothelial cells and in periaxonal astrocyte expansions. The GLUT-3 isoform is observed with TEM only in axons in the axonal bundles.ConclusionsTissue culture is suitable for apoptosis-induction experiments. The results suggest that glucose is transported to the axonal cleft intracytoplasmically and delivered to the cleft by GLUT1 transporters. As monocarboxylate transporters have been reported in the prelaminar region of the optic-nerve head, this area is likely to use both lactate and glucose as energy sources.

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“…This may take place irrespective of the cause of elevated resistance to the outflow of aqueous [40,41]. Glaucoma can be complicated by ischemic processes if the IOP rises to levels incompatible with blood perfusion.…”

Section: A New Member Of the Metabolic Paradigm?mentioning

confidence: 99%

“…Both mechanisms may combine in opposing intra-axonal flow [46]. In the misdirection hypothesis the permeability of the anterior surface of the disc is the feature to be characterized [40,41].…”

Section: The Optic Nervementioning

confidence: 99%

Glaucoma as a Tax on Hominid Evolution. Constraints of the Experimental Animal Models of Glaucoma

Carreras¹

2016

J Clin Exp Ophthalmol

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Glaucoma continues to be a mysterious disease. High intraocular pressure (IOP), once the landmark of the disease, has been relegated to the humble role of risk factor, despite the fact that lowering IOP continues to be the only partially successful treatment. Even with an IOP successfully controlled to statistical standards, many patients still mysteriously continue to progressively lose neural tissue. A novel pathogenetical mechanism has recently been put forward as the main agent of the disease. In this new light, some structural details of the human eye, the result of the peculiar evolutionary development, take on an unexpected role in the presentation of the disease. As results of cladistics analysis, the human eye appears as particularly prone to suffering glaucoma as a consequence of the evolutionary path taken. That makes glaucoma essentially a human (and related hominid) scourge. Exclusive features of the human eye compared to other vertebrates involve both the anterior and posterior segment. Those features that facilitate glaucoma in humans are absent in many of the purported animal models for the disease, and this inadequacy further convolutes the mystery of glaucoma. This suggests the division of the animal models into those that mimic the whole disease and those that only reproduce a pertinent histological feature. Unfortunately most animal models are based on high intraocular pressure which excludes most cases of low or moderate pressure. For any animal model, it is important the researcher accurately establishes the constraints of the model in order to avoid jumping to conclusions.

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Mapping the surface astrocytes of the optic disc: a fluid‐conducting role of the astrocytic covering of the central vessels

Cited by 10 publications

References 10 publications

On the protective role of the blood vessels in glaucomatous damage: a transversal study

On the protective role of the blood vessels in glaucomatous damage: a transversal study

Expression of Glucose Transporters in the Prelaminar Region of the Optic-Nerve Head of the Pig as Determined by Immunolabeling and Tissue Culture

Glaucoma as a Tax on Hominid Evolution. Constraints of the Experimental Animal Models of Glaucoma

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