PubMed Health⌕ Search

Biomedical subjects

W J Grodzki

Publications and source records attributed to W J Grodzki.

At least 19 recordsLinked to original sources
PubMed1985

Mechanism of glaucoma secondary to increased venous pressure.

Model experiments and mathematical analysis of intraocular pressure and blood flow show that as venous pressure is increased there is a rapidly increasing tendency for intraocular veins to collapse. Vein collapse slows blood flow markedly. We propose that the visual field loss in glaucoma secondary to elevated venous pressure is associated with intraocular vein collapse and retardation of intraocular blood flow.

Eye↗
PubMed1985

Perfusion outflow facility in the rabbit eye. Stabilization by EACA.

The time-dependent increase in apparent facility of outflow (washout effect) that occurs with prolonged perfusion of the eye has imposed limitations on the study of aqueous humor dynamics. The washout effect in postmortem in situ rabbit eyes, undergoing constant pressure perfusion with a saline perfusate, can be attenuated dramatically by adding to the perfusate the serine protease inhibitor and antifibrinolytic agent epsilon-aminocaproic acid (EACA) at a concentration of 3.8 X 10(-3) molar. Washout curves from 13 pairs of rabbit eyes, plotted as outflow facility versus time, were fitted by linear regression, and their washout slopes calculated. The washout slope of all of the 13 eyes perfused with normal saline + EACA was lower in magnitude (less washout) than the paired control eye in the same animal, perfused with a control perfusate of normal saline + leucine. Wilcoxon signed rank test yielded P less than 0.001. This suggests that a significant component of the washout effect may be mediated by fibrinolytic activity, or by some EACA sensitive component of the aqueous drainage pathway, and that addition of EACA to a saline perfusate may be useful for blunting the washout effect in prolonged perfusion studies.

Aminocaproates↗
PubMed1984

Proptosis and increase of intraocular pressure in voluntary lid fissure widening.

The eyeball proptoses about 0.5 mM and increases in intraocular pressure (IOP) about 2 mmHg with voluntary widening of the lid fissure. The findings probably result from the retraction of the upper lid into the orbit, thus increasing the volume of orbit contents and forcing the eyeball forward. Decrease in IOP with repeated tonometry may result, in part, from decay of the increased pressure induced by lid fissure widening.

Eyelids↗
PubMed1982

The effect of lens depression on the components of outflow resistance.

The effect of lens depression on resistance to flow through the inner wall of Schlemm's canal, circumferentially along the canal, and through the collector channels was measured in enucleated eyes. In one series of experiments the anterior chamber was perfused while canal pressure was monitored, thus allowing us to estimate inner wall resistance and a combination of canal plus collector-channel resistance. In a second series of experiments the inner canal wall was blocked with oil while the canal was perfused, allowing us to measure both circumferential flow resistance and collector-channel resistance. Lens depression decreased inner canal wall resistance in five of five eyes and decreased circumferential flow plus collector-channel resistance in one of eight eyes. These results suggest that tensing the trabecular mesh increases canal inner wall porosity and opens the canal when it is partially collapsed.

Aged↗
PubMed1981

Constant-area applanation tonography.

A tonography device, based on the MacKay-Marg tonometer, has been constructed which will applanate the cornea to a preselected area of 5.0 to 6.0 mm diameter and maintain that applanation area. The pressure decrease with time should resemble the pressure decrease following bolus injection of fluid into the eye. In most cases the pressure decreased in a linear slope, abruptly terminating in a pressure plateau. In most cases, the pressure after 4 min of tonography was lower than preliminary Goldmann applanation pressure.

Calibration↗
PubMed1981

Schlemm's canal: the effect of intraocular pressure.

We have shown that in the excised eye when oil in the anterior chamber has made the trabecular mesh impermeable, resistance to circumferential flow along the canal increases moderately as transmural pressure is increased. At the same time, resistance to outflow from the canal through the collector channels increases markedly as transmural pressure is increased from low levels to 35 or 40 mm Hg. We have suggested that the usual primary defect in open-angle glaucoma is reduced facility of the inner canal wall and that collapse of the canal with reduction of filtering area and plugging of collector channels is a secondary effect.

Anterior Chamber↗
PubMed1979

The pneumatonograph. A laboratory study.

The scale reading of the pneumatonograph (PTG) is dependent on the force of application to the cornea. Since this force is relatively greater at low intraocular pressure, the scale is compressed, yielding an overestimate of intraocular pressure in physiologic range. When the PTG is held vertically, the weight of the plunger is added to the gas propulsion force and the compression of the scale is accentuated. When a 10-g plunger load is added, as is advocated for tonography, the scale compression is further accentuated. We conclude that the PTG scale is compressed, the PTG is position-sensitive, and that the PTG is totally unsuited to tonography. The PTG is not an applanation tonometer and should not be confused with applanation tonometers.

False Positive Reactions↗
PubMed1978

Increased corneal thickness simulating elevated intraocular pressure.

A 17-year-old girl had intraocular pressure readings of 30 to 40 mm Hg in both eyes, with normal visual fields and optic nerve heads. Medical treatment was unsuccessful in lowering the IOP measurements substantially. The central corneal thickness was 0.90 mm in each eye in the absence of corneal edema. Cannulation of the left anterior chamber revealed an IOP of 11 mm Hg, while the Perkins' and Schiŏtz' tonometers gave readings of 35 and 34 mm Hg, respectively. Previously, elevated tonometry readings had been obtained by Goldmann's, Perkins', Schiŏtz', MacKay and Marg's, pneumatic tonometer and air puff tonometer. This suggested that measurement of central corneal thickness be performed in cases in which IOP recordings do not correspond to other clinical findings.

Adolescent↗
PubMed1977

The scleral spur and scleral roll.

The scleral spur and scleral roll together form a fibrous hoop which may be detached from adjacent structures as a unit. Tensile tests of the spur-roll resemble reported data on sclera. It is proposed that the circular structure of the spur-roll prevents action of the meridional portion of the ciliary muscle on the trabecular meshwork from collapsing the canal of Schlemm.

Aged↗
PubMed1977

Choroid tension and facility of aqueous outflow.

Tension of the choroid of enucleated eyes was adjusted by incising the sclera and lengthening the eye. The facility of outflow increased in direct proportion to choroid stretch. The present results are compared with reported results of anterior chamber deepening and lens depression in vitro and with accommodation and goniospasis in vivo. Choroid stretch in the enucleated eye is less efficient in increasing outflow facility than is equivalent choroid movement in accommodation. Anterior chamber deepening and lens depression also appear to be relatively inefficient means of enhancing outflow facility, although goniospasis appears to be relatively efficient. The suggestion is made that traction of the ciliary body on the trabecular mesh in an axipetal direction is more efficient in enhancing outflow facility than is traction in the meridional direction.

Accommodation, Ocular↗