Pupilometer with pupil irregularity detection capability

• US 6,116,736 A
• Filed: 04/23/1999
• Issued: 09/12/2000
• Est. Priority Date: 04/23/1999
• Status: Expired due to Term

• Current Assignee: Neuroptics Incorporated
• Original Assignee: Neuroptics Incorporated
• Inventors: Oliver, Jeffrey, Siminou, Kamran, Stark, Lawrence W., Privitera, Claudio M.
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US09/298,670
• Time in Patent Office: 508 Days
• Field of Search: 351/204, 351/206, 351/210, 351/211, 351/212, 351/246
• US Class Current: 351/206
• CPC Class Codes: A61B 3/112 for measuring diameter of pupils

Abstract

A pupilometer having a pupil irregularity or non-uniformity detection capability. The pupilometer may comprise an imaging sensor for generating signals representative of a pupil of an eye, a data processor; and a program executable by the data processor for enabling the data processor to process signals received from the imaging sensor and to thereby identify one or more regions of non-uniformity within an image of a perimeter of the pupil. The pupilometer may incorporate several innovative calibration and thresholding routines and may provide the basis for an innovative medical diagnostics system, when coupled to a network containing a suitable medical database and data processing hardware.

Claims

1. A pupilometer comprising:

a CMOS sensor for generating image data representative of a pupil of a patient; and

deformation detection means coupled to said CMOS sensor for identifying one or more selected regions within an image of a perimeter of said pupil that exhibit a predetermined amount of regional distortion.

2. A pupilometer comprising:

a microprocessor;

a memory coupled to said microprocessor;

an imaging device coupled to said microprocessor;

a visible light source coupled to said microprocessor;

an IR light source coupled to said microprocessor; and

a display coupled to said microprocessor;

said memory having stored therein a program for enabling said microprocessor to cause a plurality of visible light stimulus pulses to be generated by said visible light source, to cause said IR light source to generate IR light for illuminating a pupil, to enable said imaging device to acquire a plurality of images of said illuminated pupil, to process data sets representative of said images of said illuminated pupil to obtain information descriptive of a response of said pupil to said visible light stimulus pulses, and to cause said information to be depicted on said display;

said information descriptive of a response of said pupil to said visible light stimulus pulses comprising information indicative of a degree of non-uniform deformation of a selected segment of a perimeter of said pupil.

3. A handheld pupilometer comprising:

a housing having a display, microprocessor, memory, imaging device, visible light source and IR light source mounted therein;

said microprocessor being electronically coupled to said display, said memory, said imaging device, said visible light source and said IR light source; and

said memory having stored therein a program for enabling said microprocessor to cause at least one visible light stimulus pulse to be generated by said visible light source, to cause said IR light source to generate IR light for illuminating a pupil, to enable said imaging device to acquire a plurality of images of said illuminated pupil, and to process a plurality of data sets representative of said plurality of images of said illuminated pupil to obtain information descriptive of a response of said pupil to said at least one visible light stimulus pulse, and to cause said information to be depicted on said display;

said information descriptive of a response of said pupil to said at least one visible light stimulus pulse comprising information indicative of a degree of deformation of a selected segment of a perimeter of said pupil.

4. The handheld pupilometer of claim 3, wherein said information descriptive of a response of said pupil to said at least one visible light stimulus pulse comprises information descriptive of a dynamic response of said selected segment of said perimeter of said pupil.

5. The pupilometer of claim 3, wherein said imaging device comprises a CMOS N×

M sensor.

6. The pupilometer of claim 3, wherein said imaging device comprises a CCD camera.

7. The pupilometer of claim 3 further comprising means coupled to said microprocessor for downloading to a remote storage device said information descriptive of a response of said pupil to said at least one visible light stimulus pulse.

8. The pupilometer of claim 7 wherein said means for downloading comprises at least one of either an IR transmitter circuit or a RF transmitter circuit.

9. The pupilometer of claim 7 wherein said means for downloading comprises at least one of either a data port or a modem for coupling said pupilometer to a computer.

10. The pupilometer of claim 9, wherein said means for acquiring image data comprises a source of infrared light, a source of visible light and an imaging device under microprocessor control.

11. The pupilometer of claim 10, wherein said imaging device is selected from a group consisting of a CCD camera and a N×

M CMOS imaging sensor.

13. The pupilometer of claim 10, wherein said means for acquiring image data comprises a source of infrared light, a source of visible light and an imaging device under micrprocessor control.

12. A handheld pupilometer comprising:

a housing having mounted therein means for acquiring image data representative of ocular tissue, means for processing said image data, and means for displaying information derived from said image data,

said means for processing said image data comprising a microprocessor and programming for determining a pixel brightness threshold value, programming for locating a pupil within a plurality of image data sets using said pixel brightness threshold value, and programming for identifying one or more regions around a perimeter of said pupil that exhibit a non-uniform change in shape when said pupil is exposed to illumination of a predetermined type.

14. The pupilometer of claim 12, wherein said illumination comprises exposure to ambient light.

15. A method for correlating pupilary responses with pathological indications, said method comprising the steps of:

storing within a database data representative of a plurality of pupilary response characteristics associated with one or more pathological indications;

using a pupilometer obtaining pupilary response data from a patient, said pupilary response data being representative of one or more pupilary response characteristics of said patient; and

comparing within a data analysis system said pupilary response data obtained from said patient with said data representative of a plurality of pupilary response characteristics to identify one or more pathological conditions of said patient.

16. A method for correlating pupilary measurements with pathological indications, said method comprising the steps of:

storing within a database data representative of a plurality of pupilary configurations and associated pathological conditions;

using a pupilometer obtaining pupilary configuration data from a patient; and

comparing within a data analysis system said pupilary configuration data obtained from said patient with said data representative of said plurality of pupilary configurations to identify one or more pathological conditions of said patient.

17. The method of claim 16, wherein said pupilary configuration data comprises data descriptive of a pupilary response to at least one visible light stimulus pulse.

18. The method of claim 16, wherein said pupilary configuration data comprises data descriptive of a pupilary change in shape responsive to at least one light stimulus pulse.

19. The method of claim 16, wherein said pupilary configuration data comprises data descriptive of a pupilary response to ambient light exposure.

20. A method for correlating pupilary responses with pathological indications, said method comprising the steps of:

storing within a database data representative of a plurality of pupilary sectional configurations and associated pathological conditions;

using a pupilometer obtaining pupilary configuration data from a patient, said pupilary configuration data including data indicative of selected regional non-uniformities of a pupil of said patient if said patient'"'"'s pupil exhibits such regional non-uniformities; and

comparing within a data analysis system said pupilary configuration data obtained from said patient with said data representative of said plurality of pupilary sectional configurations to identify one or more pathological conditions of said patient.

21. A method for correlating pupilary responses with a scalar value indicative of a state of health of an individual or physiological system of said individual, said method comprising the steps of:

storing within a database data representative of a plurality of pupilary response characteristics associated with one or more pathological indications;

using a pupilometer obtaining pupilary response data from a patient, said pupilary response data being representative of one or more pupilary response characteristics of said patient; and

comparing within a data analysis system said pupilary response data obtained from said patient with said data representative of said plurality of pupilary response characteristics to derive said scalar value.

22. A system for use in diagnosing pathological conditions, said system comprising:

a pupilometer for obtaining data descriptive of one or more pupilary characteristics from a patient;

a database for storing data descriptive of a plurality of pupilary characteristics and associated physical conditions; and

a central processing unit coupled to said digital pupilometer and said database for comparing said data obtained by said pupilometer to said data stored within said database such that a pathological condition of said patient may be diagnosed based upon said comparison.

23. The system of claim 22 further comprising a processing subroutine for generating a scalar indicator based upon a result of said step of comparing said data stored within said pupilometer to said data stored within said database.

24. The system of claim 22 further comprising a display coupled to said central processing unit for displaying images of said patient'"'"'s pupil and for providing an indication of whether or not said pupilary characteristics of said patient correspond to any of said pupilary characteristics represented by said data stored within said database.

25. A method for locating a pupil within an image of ocular tissue, said method comprising the steps of:

establishing a pixel brightness threshold value for discriminating between light and dark gray scale data comprising said image, and

comparing gray scale image data at a plurality of pixel locations within said image of ocular tissue to said pixel brightness threshold value to identify a region within said image of ocular tissue that represents said pupil,

wherein said step of establishing a pixel brightness threshold value comprises the steps of selecting a pixel brightness threshold value, constructing vertical and horizontal histogram data sets from said image of ocular tissue, wherein each histogram data set comprises a plot of sums of pixel locations having a value exceeding said threshold value along respective rows or columns of pixels comprising said image, determining whether curves mapped from said vertical and horizontal histogram data sets comprise at least one maximum value bordered by a pair of null values, and repeating said selecting, constructing and determining steps until a pixel brightness threshold value is identified that satisfies said determining step.

26. The method of claim 25, wherein said step of selecting a pixel brightness threshold value comprises the steps of selecting a maximum pixel brightness threshold value and decreasing said pixel brightness threshold value in increments from said maximum pixel brightness threshold value upon each repetition of said selecting step.

27. The method of claim 25, wherein said step of selecting a pixel brightness threshold value comprises the steps of selecting a minimum pixel brightness threshold value and increasing said pixel brightness threshold value in increments from said minimum pixel brightness threshold value upon each repetition of said selecting step.

28. The method of claim 27, wherein said assigning step comprises the step of deriving a pixel brightness threshold value comprising the sum of the relative minimum pixel brightness threshold value and 2/3 times the difference between the relative maximum and relative minimum pixel brightness threshold values.

29. The method of claim 25, wherein said step of selecting a pixel brightness threshold value comprises the steps of

selecting a maximum pixel brightness threshold value and decreasing said pixel brightness threshold value in increments from said maximum pixel brightness threshold value until a first predetermined histogram plot is achieved and a relative maximum pixel brightness threshold value is identified,

selecting a minimum pixel brightness threshold value and increasing said pixel brightness threshold value in increments from said minimum pixel brightness threshold value until a second predetermined histogram plot is achieved and a relative minimum pixel brightness threshold value is identified, and

assigning said pixel brightness threshold value a level between said relative maximum pixel brightness threshold value and said relative minimum pixel brightness threshold value.

30. A method of processing data representative of an image of ocular tissue, said method comprising the steps of:

generating digital image data representative of said image of said ocular tissue;

processing said digital image data representative of said image of said ocular tissue to locate one or more landmarks within said image of said ocular tissue;

using said one or more landmarks determine whether a right eye or left eye of a patient is being monitored.

31. A method of calibrating a pupilometer comprising the steps of:

acquiring at least one data set representative of an image of an eye including a pupil and an iris,

deriving from said at least one data set information descriptive of a shape of an outer perimeter region of said iris,

deriving from said at least one data set information descriptive of a shape of a perimeter region of said pupil, and

comparing said information descriptive of said shape of said outer perimeter region of said iris to said information descriptive of said perimeter region of said pupil to normalize and establish a frame of reference for said information descriptive of said shape of said pupil.

32. A method for calibrating a pupilometer comprising the steps of:

acquiring at least one data set representative of an image of an eye including a pupil and an iris,

deriving from said at least one data set an indication of a diameter of an outer perimeter of said iris,

comparing said indication of said diameter of said outer perimeter of said iris to an assumed diameter of said iris, and

utilizing a difference between said indication of said diameter of said outer perimeter of said iris and said assumed diameter to calibrate said pupilometer.

33. The method of claim 32, wherein said assumed diameter of said iris is a horizontal diameter and is approximately 11.75 mm.

34. A method for calibrating a pupilometer comprising the steps of:

illuminating a portion of an eye including an iris and a pupil with low intensity blue light,

using an imaging sensor, obtaining data descriptive of an image of said portion of said eye illuminated by said low intensity blue light,

analyzing said data to identify an outer perimeter of said iris of said eye within said image, and

using said identified outer perimeter of said iris of said eye to calibrate said pupilometer.

35. A method for acquiring pupilometry data, said method comprising the steps of:

exposing an eye of a patient to blue light pulses and IR pulses in a predetermined sequence,

obtaining data descriptive of a shape of an iris of said eye when said eye is exposed to said blue light pulses, and

obtaining data descriptive of a shape of a pupil of said eye when said eye is exposed to said IR pulses.

36. The method of claim 35, wherein said light pulses and IR pulses, and said respective data obtaining steps, are multiplexed.

37. A method of calibrating a pupilometer, said method comprising the steps of:

exposing an eye to a plurality of light stimulus pulses,

using said pupilometer obtaining a plurality of image data sets representative of respective pupilary responses of said eye to said light stimulus pulses,

using said plurality of obtained image data sets deriving response curves representative of said respective pupilary responses, and

using said response curves to evaluate a degree of adaptation of said eye to said stimulus pulses.

38. The method of claim 37 further comprising the step of using an estimate of said degree of accommodation of said eye to said stimulus pulses to normalize one or more image data sets representing a pupilary response to a selected stimulus pulse.

39. A pupilometry system comprising:

a display, microprocessor, memory, imaging device, first and second visible light sources and an IR light source;

said microprocessor being electronically coupled to said display, said memory, said imaging device, said visible light sources and said IR light source; and

said memory having stored therein a program including stimulus control code for enabling said microprocessor to cause said first visible light source to generate a first visible light stimulus pulse for illuminating a first eye, to cause said second visible light source to generate a second visible light stimulus pulse for illuminating a second eye at a predetermined time following termination of said first visible light stimulus pulse, and to cause said first visible light source to generate a third visible light stimulus pulse for illuminating said first eye at a predetermined time following termination of said second visual light stimulus pulse;

including illumination control code for enabling said microprocessor to cause said IR light source to generate IR light for illuminating a pupil of said first eye during a duration of said first, second and third visible light stimulus pulses;

including image acquisition code for enabling said microprocessor to cause said imaging device to acquire a plurality of images of said IR illuminated pupil;

including image analysis code for enabling said microprocessor to process data sets representative of said images of said IR illuminated pupil to obtain information descriptive of a response of said pupil to said visible light illumination of said first eye and said second eye; and

display code for enabling said microprocessor to cause said information to be depicted on said display.

40. The pupilometer of claim 39 further comprising an armature that extends from a main body of said pupilometer for supporting said second visible light source.

41. The pupilometer of claim 40, wherein said armature detachably engages said main body of said pupilometer.