Method of Estimating Ocular Perfusion Pressure
First Claim
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1. A method of estimating mean central retinal artery pressure (MCRAP) by using a microprocessor controlled tonometer, the method comprising:
- using the tonometer to determine a mean intraocular pressure (MIOP) including a diastolic value and a systolic value having an ocular pulse amplitude (OPA);
using the microprocessor to calculate a ratio of OPA to MIOP;
using the microprocessor to derive a multiplier from the ratio; and
using the microprocessor to multiply MIOP by the derived multiplier to produce an estimate of mean central artery pressure (MCRAP).
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Abstract
A microprocessor-controlled tonometer measures both systole and diastole occurring in intraocular pressure so that this information can be used to estimate perfusion pressure. The microprocessor determines a ratio between ocular pulse amplitude and mean intraocular pressure, derives a multiplier from the ratio, multiplies the mean intraocular pressure by the multiplier to estimate mean central retinal artery pressure, and then estimates perfusion pressure by subtracting mean intraocular pressure from the estimate of central retinal artery pressure.
23 Citations
21 Claims
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1. A method of estimating mean central retinal artery pressure (MCRAP) by using a microprocessor controlled tonometer, the method comprising:
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using the tonometer to determine a mean intraocular pressure (MIOP) including a diastolic value and a systolic value having an ocular pulse amplitude (OPA); using the microprocessor to calculate a ratio of OPA to MIOP; using the microprocessor to derive a multiplier from the ratio; and using the microprocessor to multiply MIOP by the derived multiplier to produce an estimate of mean central artery pressure (MCRAP). - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of estimating ocular perfusion pressure by using a microprocessor controlled tonometer having a cornea engaging surface, the method comprising:
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using the tonometer to determine a mean intraocular pressure (MIOP) while the cornea engaging surface presses lightly against the cornea of the eye; pressing the corneal engaging surface against the cornea of the eye with increased force while measuring diminishment of an amplitude of ocular pulses (OPA); programming the microprocessor to estimate Mean Central Retinal Artery Pressure (MCRAP) from an approximately linear and inverse relationship between increasing cornea engaging surface pressure and diminishing OPA; and using the microprocessor to estimate ocular perfusion pressure by subtracting the MIOP from the estimated MCRAP - View Dependent Claims (8, 9, 10)
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11. A method of estimating mean central retinal artery pressure (MCRAP) by using a microprocessor controlled tonometer having a cornea engaging surface pressable against a cornea, the method comprising:
using the tonometer to press the cornea engaging surface lightly against the cornea so that the microprocessor determines and uses the following; a diastolic IOP; a systolic IOP; a mean IOP (MIOP) based on 2 times the diastolic IOP plus the systolic IOP divided by 3; a ratio of measured ocular pulse amplitude (OPA) divided by MIOP; a multiplier derived from the ratio; and an estimate of mean central retinal artery pressure (MCRAP) derived from multiplying MIOP by the multiplier. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method of estimating ocular perfusion pressure by using a microprocessor controlled tonometer that presses a surface against a cornea of an eye being examined, the method comprising:
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measuring brachial blood pressures of each arm of a person in an upright position; entering the brachial blood pressures into the microprocessor; using the microprocessor to determine a mean intraocular pressure (MIOP) from 2 times a diastolic IOP plus a systolic IOP divided by 3; using the microprocessor to measure an ocular pulse amplitude (OPA); using the microprocessor to determine a ratio based on OPA divided by MIOP; using the microprocessor to derive a multiplier from the ratio and to multiply MIOP by the multiplier to produce an estimate of mean central retinal artery pressure (MCRAP); using the microprocessor to compare the estimate of MCRAP with 60% of an ipsilateral brachial pressure; and using the microprocessor to estimate perfusion pressure by subtracting MIOP from MCRAP.
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18. A method of estimating mean central retinal artery pressure (MCRAP) by using a microprocessor controlled tonometer having a cornea engaging surface, the method comprising:
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measuring an ipsilateral brachial blood pressure for an eye being examined and entering the brachial blood pressure for the microprocessor to determine 60% of the measured blood pressure value; and using the tonometer to measure ocular pulse amplitude (OPA), and a mean intraocular pressure (MIOP);
calculating a ratio of OPA divided by MIOP;
deriving a multiplier from the ratio; and
multiplying MIOP by the multiplier to estimate MCRAP; andcomparing the brachial estimate of MCRAP with the measured OPA based estimate of MCRAP. - View Dependent Claims (19, 20, 21)
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Specification