Biomaterial Database

Postural studies in pulsatile ocular blood flow: I. Ocular hypertension and normotension. 1991

D R Trew, and S E Smith

Division of Pharmacological Sciences and Toxicology, United Medical School, London.

Measurements of pulsatile ocular blood flow (POBF) have been recorded in a group of healthy, ocular normotensive volunteers and ocular hypertensive patients recruited from outpatients. Use of a pneumotonometric probe linked to a Langham ocular blood flow system enabled readings of intraocular pressure and its variation with heart rate (ocular pulse) to be taken in erect and supine positions. Pulsatile ocular blood flow was calculated from these values by means of the pressure-volume relationship previously described for living human eyes. Assumption of the supine posture was accompanied by a significant rise in intraocular pressure; in normal eyes (mean, with SEM) (3.1 (0.4) mmHg, p less than 0.0001) and to a greater extent in ocular hypertensive eyes (4.7 (0.6) mmHg, p less than 0.0001). The POBF did not differ significantly between normotensive and ocular hypertensive groups in either the erect or supine postures. In both groups, however, assumption of the supine posture was accompanied by a significant fall in POBF (normals: -121 (21) microliters/min, p less than 0.0001; ocular hypertensives: -75 (16) microliters/min, p less than 0.0002). These reductions in POBF represent decrements of 27.5 (3.0)% and 17.1 (3.8)% respectively. Pulsatile ocular blood flow is reduced in the supine posture, and this may result in tissue hypoxia in subjects at risk of developing glaucoma. A companion paper describes the measurement of POBF in a group of patients with chronic open angle glaucoma treated with topical timolol 0.25%.

UI	MeSH Term	Description	Entries
D007429	Intraocular Pressure	The pressure of the fluids in the eye.	Ocular Tension,Intraocular Pressures,Ocular Tensions,Pressure, Intraocular,Pressures, Intraocular,Tension, Ocular,Tensions, Ocular
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D009798	Ocular Hypertension	A condition in which the intraocular pressure is elevated above normal and which may lead to glaucoma.	Glaucoma, Suspect,Hypertension, Ocular,Glaucomas, Suspect,Hypertensions, Ocular,Ocular Hypertensions,Suspect Glaucoma,Suspect Glaucomas
D011187	Posture	The position or physical attitude of the body.	Postures
D011673	Pulsatile Flow	Rhythmic, intermittent propagation of a fluid through a BLOOD VESSEL or piping system, in contrast to constant, smooth propagation, which produces laminar flow.	Flow, Pulsating,Perfusion, Pulsatile,Flow, Pulsatile,Flows, Pulsatile,Flows, Pulsating,Perfusions, Pulsatile,Pulsatile Flows,Pulsatile Perfusion,Pulsatile Perfusions,Pulsating Flow,Pulsating Flows
D001794	Blood Pressure	PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.	Systolic Pressure,Diastolic Pressure,Pulse Pressure,Pressure, Blood,Pressure, Diastolic,Pressure, Pulse,Pressure, Systolic,Pressures, Systolic
D005123	Eye	The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.	Eyes
D005260	Female		Females
D005901	Glaucoma	An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)	Glaucomas