System for assessing lachrymal fluid content of a sample pad

• US 4,994,751 A
• Filed: 08/14/1989
• Issued: 02/19/1991
• Est. Priority Date: 08/14/1989
• Status: Expired due to Fees

• Current Assignee: Jerry W. Cook
• Original Assignee: Jerry W. Cook
• Inventors: Fago, Edward T. Jr., Cook, Jerry W.
• Primary Examiner(s): Wieder, Kenneth
• Assistant Examiner(s): Harvey, Jack B.
• Application Number:
  US07/393,223
• Time in Patent Office: 554 Days
• Field of Search: 324/658, 324/663, 324/664, 324/667, 324/674, 324/681, 324/686, 324/689, 324/690, 324/692, 324/661, 128/760, 128/645, 128/745, 128/771, 128/734, 422/82.02, 436/150, 436/806, 435/817
• US Class Current: 324/674
• CPC Class Codes: A61B 10/0045 Devices for taking samples of body liquids devices for taking blood samples A61B5/15
• CPC Class Codes: A61B 2010/0067 Tear or lachrymal fluid
• CPC Class Codes: A61B 3/101 for examining the tear film
• CPC Class Codes: G01N 27/22 by investigating capacitance

Abstract

A system rapidly and accurately assesses the lachrymal fluid content in a person'"'"'s eye which minimizes patient discomfort. The preferred system includes a fluid sampling device and an assessment device. The preferred sampling device includes a lachrymal fluid absorbent sample pad and a non-absorbent handle. The preferred assessment device includes a receiver for receiving a lachrymal fluid sample pad and includes a control circuit coupled with the receiver for determining the electrical capacitance of the pad which capacitance varies in accordance with variations in lachrymal fluid content, and for producing an output correlated with the lachrymal fluid quantity in the pad.

Claims

1. A lachrymal fluid assessment device comprising:

receiving means including a pair of electrodes for receiving a sample pad therebetween with the sample pad having an unknown quantity of lachrymal fluid present therein, and for presenting the sample pad for determination of the capacitance thereof, said unknown quantity being a representative sample of lachrymal fluid present in a person'"'"'s eye, said capacitance being representative of said unknown quantity; and

circuit means operably coupled with said receiving means for determining said capacitance, for producing a capacitance signal representative of said capacitance, and responsive thereof for producing an output correlated with said unknown quantity of lachrymal fluid present in the sample pad,

said circuit means including processing circuit means responsive to said capacitance signal for producing said output;

said processing circuit means including memory means for storing data correlating said output with said capacitance signal and thereby with said unknown quantity and with the amount of lachrymal fluid present in the person'"'"'s eye.

2. An assessment device as set forth in claim 1, said receiving means including a pair of spaced electrodes defining a sample pad receiving space therebetween, said circuit means including capacitance determining means for determining the capacitance between said electrodes.

3. The assessment device as set forth in claim 2, said receiving means further including means shiftably mounting said electrodes in a biased, relatively shiftable relationship toward one another and including means for selectively altering the spacing between said electrodes in order to hold a sample pad having a predetermined width therebetween.

4. The assessment device as set forth in claim 1 said processing circuit means including a microprocessor.

5. The assessment device as set forth in claim 1, said circuit means including means for producing said capacitance signal as a frequency variable signal which frequency varies in correlation with said capacitance.

6. The assessment device as set forth in claim 5, said circuit means including zeroing means for calibrating said circuit means using a sample pad without lachrymal fluid absorbed therein.

7. The assessment device as set forth in claim 1, further including display means coupled with said circuit means and responsive to said output for displaying a representation of said quantity of lachrymal fluid present in the sample pad.

8. The assessment device as set forth in claim 7, said display means including a liquid crystal digital display.

9. The assessment device as set forth in claim 7, said representation being in terms of a percentile.

10. The assessment device as set forth in claim 1, said receiving means further including detection means for detecting the presence of a sample pad therein.

11. The assessment device as set forth in claim 1, said data being stored in said memory means as a look-up table.