Aqueous Veins in Glaucomatous Eyes

Thomassen, Thore Lie; Perkins, E. S.; Dobree, J H

doi:10.1136/bjo.34.4.221

Cited by 37 publications

(13 citation statements)

References 4 publications

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“…42,43 Experimentally controlled increases in IOP induced by pressure on the side of the eye, [44][45][46] ophthalmodynamometry, 47,48 or water drinking 7 result in enhanced pulsatile aqueous outflow. When IOP is reduced below its physiologic set point, pulsatile flow stops, but begins again when IOP rises to the homeostatic set point.…”

Section: Pulsatile Aqueous Outflow: a Role In Iop Homeostasismentioning

confidence: 99%

Intraocular Pressure Regulation: Findings of Pulse-Dependent Trabecular Meshwork Motion Lead to Unifying Concepts of Intraocular Pressure Homeostasis

Johnstone

2014

Journal of Ocular Pharmacology and Therapeutics

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Intraocular pressure (IOP) is the only treatable risk factor in glaucoma, one of the world's leading causes of blindness. Mechanisms that maintain IOP within a normal range have been poorly understood in contrast to intrinsic mechanisms that regulate systemic blood pressure. Vessel walls experience continuous pulse-induced cyclic pressure and flow. Pressure-dependent wall stress and flow-dependent shear stress provide sensory signals that initiate mechanotransduction responses. The responses optimize vessel wall elasticity, compliance and lumen size, providing a feedback loop to maintain intrinsic pressure homeostasis.Aqueous humor is part of a vascular circulatory loop, being secreted into the anterior chamber of the eye from the vasculature, then returning to the vasculature by passing through the trabecular meshwork (TM), a uniquely modified vessel wall interposed between the anterior chamber and a vascular sinus called Schlemm's canal (SC). Since pressure in circulatory loops elsewhere is modulated by cyclic stresses, one might predict similar pressure modulation in the aqueous outflow system. Recent laboratory evidence in fact demonstrates that cyclic IOP changes alter aqueous outflow while increasing cellularity and contractility of TM cells. Cyclic changes also lead to alterations in gene expression, changes in cytoskeletal networks and modulation of signal transduction. A new technology, phase-based optical coherence tomography, demonstrates in vivo pulse-dependent TM motion like that elsewhere in the vasculature. Recognition of pulse-dependent TM motion provides a linkage to well-characterized mechanisms that provide pressure homeostasis in the systemic vasculature. The linkage may permit unifying concepts of pressure control and provide new insights into IOP homeostatic mechanisms.

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Section: Pulsatile Aqueous Outflow: a Role In Iop Homeostasismentioning

confidence: 99%

Intraocular Pressure Regulation: Findings of Pulse-Dependent Trabecular Meshwork Motion Lead to Unifying Concepts of Intraocular Pressure Homeostasis

Johnstone

2014

Journal of Ocular Pharmacology and Therapeutics

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“…The nerve damage involves loss of retinal ganglion cells in a characteristic pattern. It is often, but not always, associated with increased pressure of the fl uid in the anterior cavity of the eye (aqueous humor, AH) (1) . With pharmaceutical and/or surgical intervention it is possible to halt further loss of vision.…”

Section: Introductionmentioning

confidence: 99%

Biomarkers in primary open angle glaucoma

Kokotas

Kroupis

Chiras

et al. 2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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Glaucoma, a leading cause of blindness worldwide, is currently defi ned as a disturbance of the structural or functional integrity of the optic nerve that causes characteristic atrophic changes in the optic nerve, which may lead to specifi c visual fi eld defects over time. This disturbance usually can be arrested or diminished by adequate lowering of intraocular pressure (IOP). Glaucoma can be divided roughly into two main categories, ' open angle ' and ' closed angle ' glaucoma. Open angle, chronic glaucoma tends to progress at a slower rate and patients may not notice loss of vision until the disease has progressed signifi cantly. Primary open angle glaucoma (POAG) is described distinctly as a multifactorial optic neuropathy that is chronic and progressive with a characteristic acquired loss of optic nerve fi bers. Such loss develops in the presence of open anterior chamber angles, characteristic visual fi eld abnormalities, and IOP that is too high for the healthy eye. It manifests by cupping and atrophy of the optic disc, in the absence of other known causes of glaucomatous disease. Several biological markers have been implicated with the disease. The purpose of this study was to summarize the current knowledge regarding the non-genetic molecular markers which have been predicted to have an association with POAG but have not yet been validated.

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“…Observations on aqueous veins have established that the ouflow of aqueous in glaucomatous eyes is not constant but varies according to whether the tension is in a rising or falling phase (Thomassen, 1947;Thomassen, Perkins, and Dobree, 1950). These findings can be correlated with the results observed in the fluorescein instillation test.…”

Section: Discussionmentioning

confidence: 87%

Clinical Method of Observing Changes in the Rate of Flow of Aqueous Humour in the Human Eye : II. In Glaucoma

Langley¹,

Macdonald²

1952

British Journal of Ophthalmology

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IN a previous paper (Langley and MacDonald, 1952), the fluorescein instillation test was described and the results obtained in normal human eyes discussed. It was seen that the instillation of 10 per cent. fluorescein solution into the conjunctival sac resulted in the appearance of the dye in the aqueous humour, and that the concentration in the aqueous of normal eyes fell off slowly and evenly over a period of as long as 24 hours. The concentration was reduced by approximately 1 part per 100 million parts per hour. The level at any moment was held to represent a steady state between the concentration of fluorescein in the cornea and that in the aqueous, modified by the normal steady flow of aqueous; and this flow was responsible for the eventual disappearance of the dye from the anterior chamber. It was also emphasized that any sudden fall in fluorescein concentration indicated an increase in the rate of flow of aqueous, and that drainage of aqueous from the anterior chamber without its replacement by clear fluid would produce no change in the concentration.In the present paper, the results in glaucomatous eyes are described, and the significance of these results in relation to certain of the known features of the disease is discussed.METHOD.-The test was carried out as described in the previous paper. Miotic treatment, if used, was withheld for 24 hours before the test. The patient instilled the fluorescein drops himself either on rising on the morning of the test or before retiring the previous evening. In this way the concentration of fluorescein in the aqueous would have reached and passed its maximum before the observations commenced at 9.30 a.m. After a period of observation, a miotic (usually pilocarpine 1 per cent. or 2 per cent. and in some cases eserine 1 per cent.) was instilled and further observations recorded. The fluorescein concentration was estimated by the method of Amsler and Huber (1946) and transposed into terms of actual concentration of the dye from the conversion curve shown in the previous paper. The ocular tension was taken at intervals with a Schiotz X-tonometer, pantocaine 1 per cent. anaesthesia being used for this purpose. Following the instillation of miotics the pupil in some eyes became so small that readings with the usual breadth of the beam of light became difficult, and it was found that when this occurred, the readings could be accurately checked by using the smallest aperture of the Haag-Streit slit lamp. Readings taken with the smallest beam were checked against those taken with the usual aperture in the calibrated apparatus, and were found to be consistently 0.1 amp. lower except in the highest ranges of fluorescein concentration.

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Aqueous Veins in Glaucomatous Eyes

Cited by 37 publications

References 4 publications

Intraocular Pressure Regulation: Findings of Pulse-Dependent Trabecular Meshwork Motion Lead to Unifying Concepts of Intraocular Pressure Homeostasis

Intraocular Pressure Regulation: Findings of Pulse-Dependent Trabecular Meshwork Motion Lead to Unifying Concepts of Intraocular Pressure Homeostasis

Biomarkers in primary open angle glaucoma

Clinical Method of Observing Changes in the Rate of Flow of Aqueous Humour in the Human Eye : II. In Glaucoma

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