Diagnosing open angle glaucoma.
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Chronic Disease↗
Biomedical subjects
M F Armaly
Publications and source records attributed to M F Armaly.
Sites of breakdown of the blood-aqueous barrier after paracentesis of the rhesus monkey eye.
Sites of breakdown of the blood-aqueous barrier following rapid paracentesis have been investigated in rhesus monkeys with two independent procedures. (1) The entrance of fluorescein into the anterior and posterior chambers following paracentesis was studied in vivo in normal eyes, in eyes with laser-induced experimental glaucoma, and in totally iridectomized eyes. (2) Scanning electron microscopy was used to study the ciliary body and trabecular meshwork regions in normal eyes and paracentetic eyes. These investigations show that the ciliary body, particularly the anterior pars plicata region, is a source of secondary aqueous humor protein. In addition, the study shows reflux of blood into Schlemm's canal and plasma movement across the inner wall into the anterior chamber.
Animals↗
Measurement of episcleral venous pressure.
Using materials available in any ophthalmology clinic, we constructed a useful and reliable instrument for measuring episcleral venous pressure. The instrument, a modification of the pressure chamber method of Seidel, utilizes a latex membrane and an air-filled chamber. These modifications facilitated ease of preparation for the measurement. Episcleral venous pressure in normal subjects was 9.0 +/- 1.6 mm Hg (mean +/- S.D.). Measurement of episcleral venous pressure facilitated diagnosis of diseases such as arteriovenous fistula and superior vena caval obstruction, which block drainage of venous blood from the orbit.
Adult↗
Optic nerve circulation and ocular pressure: contribution of central retinal artery and short posterior ciliary arteries and the effect on oxygen tension.
Blood-flow rate in the optic nerve of the rhesus monkey 4 mm. behind the globe monitored by the heated thermocouple and tissue p02 measurement is found to be influenced by ocular pressure level. Ligation of central retinal artery reduced flow rate to 79 per cent of normal but did not influence the effect of IOP on blood-flow rate. Ligation of short posterior ciliary arteries reduced blood-flow rate to 21 per cent of normal and virtually eliminated the IOP effect. Raising IOP to above systolic arterial pressure level reduced blood-flow rate to 17 per cent of normal. At IOP levels greater than 50 mm. Hg, the reduction in blood-flow rate and in Po becomes marked and may be sufficient to produce primary lesions at this site.
Animals↗
Effect of ocular pressure on choroidal circulation in the cat and Rhesus monkey.
Using the heated thermocouple principle to monitor blood flow-rate in the choroid of the anesthetized cat and Rhesus monkey revealed that elevation of ocular pressure reduces blood flow-rate in the choroidal circulation. The magnitude of this effect at varying levels of ocular pressure led to the conclusion that the vascular bed of the choroid in these experimental animals is a passive one without evidence of active regulation.
Animals↗
Demonstration of acid mucopolysaccharides in the trabecular meshwork of the Rhesus monkey.
The ability to demonstrate AMPS in the trabecular region in the normal eye of the Rhesus monkey was shown to be critically dependent upon technical variation. Staining the fixed specimen prior to dehydration and embedding permits the uniform demonstration of AMPS in the trabecular region of the Rhesus monkey and shows it to be hyaluronidase-sensitive. Electron microscopy using the modified technique shows the reaction products to be present within the trabecular band, the intertrabecular spaces, and the canal of Schlemm. More impressive distribution was seen in the basement membrane of trabecular endothelium intimately related to the cell wall and in the ground substance and basement membrane of the endothelium of the inner wall of the canal Schlemm. The technique is also successful in the human eye and suggests a greater abundance of trabecular AMPS in open-angle glaucoma.
Animals↗
Optic nerve circulation and ocular pressure.
Rapid, short-lasting elevation of ocular pressure level produces simultaneous reduction in blood-flow rate in the distal 6 mm. of the extraocular portion of the optic nerve of the rhesus monkey as monitored by the heated thermocouple technique. The magnitude of this reduction was very small until intraocular pressure (IOP) exceeded 50 mm. Hg following which markedly and progressively greater reduction in blood-flow rate occurred at higher IOP levels; maximum reduction was reached at IOP of 105 mm. Hg. The magnitude of reduction in blood-flow rate for each ocular pressure level was significantly greater when systemic arterial pressure was reduced. These effects were monitored 2 to 4 mm. behind the globe and became reduced at a more proximal location, disappearing at locations further than 6 mm. from the globe. The results suggested a reduction in nutrient blood flow to the optic nerve at the monitored site with elevation of IOP.
Animals↗