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Abstract
An equation has been derived under simplified assumptions showing how the steady-state value of intraocular pressure depends on rate of secretion of aqueous, episcleral venous pressure, outflow facility at the chamber angle, colloid-osmotic pressure of the blood, systemic arterial blood pressure, pressure distribution over the vascidar tree of the eye, and filtration properties of the vasculature in different intraocular regions.
It is shoiun that intraocular fluid formation will be reduced by increased intraocular pressure in such a manner that the presence of a facility is simulated. In the conscious rabbit, this pseudofacility is estimated to account for about 10 per cent of the measured tonographic facility. Its absolute magnitude can be expected to rise with arteriolar vasodilatation (as might be caused by miotics) and to drop with arteriolar vasoconstriction.
A method is outlined ivhich should allow pseudofacility to be measured in the glaucomatous human eye.
If intraocular pressure is not excessively high, changes in arteriolar tone will tend to cause parallel changes in pressure and pseudofacility simulating homeostatic adjustment of facility to pressure.