Systems and methods for administering a gaze nystagmus test

Systems and methods for performing a Horizontal Gaze Nystagmus (HGN) test. An HGN test device having a harness configured to be worn by a subject, a moveable stimulus controlled by a computing device, and a recording device for recording the eyes of the subject during the administration of the HGN test. More specifically, the HGN device has a movable armature or an arm with a stimulus there attached which follows a track. The recording may be stored in the computing device or transmitted to a remote system for storage.

BACKGROUND OF THE INVENTION

Nystagmus is an involuntary jerking or bouncing of the eyeball that occurs when there is a disturbance of the vestibular (inner ear) system or the oculo-motor control of the eye. Horizontal gaze nystagmus (HGN) refers to a lateral or horizontal jerking when the eye gazes to the side. In the impaired driving context, alcohol consumption or consumption of certain other central nervous system depressants, inhalants or phencyclidine, hinders the ability of the brain to correctly control eye muscles causing the jerk or bounce associated with HGN. As the degree of impairment becomes greater, the jerking or bouncing of the nystagmus becomes more pronounced. This is assessed in the horizontal gaze nystagmus test.

The horizontal gaze nystagmus test is one of three field sobriety tests that comprise the standardized field sobriety test (SFST) battery (the other two tests are the walk-and-turn test and the one-leg-stand test) of the National Highway Traffic Safety Administration (NHTSA). Scientific evidence has shown the horizontal gaze nystagmus test as a reliable roadside measure of a person's impairment due to alcohol or certain other drugs.

Nystagmus describes the “bouncing” eye motion displayed in two ways: (1) pendular nystagmus, where the eye oscillates equally in two directions, and (2) jerk nystagmus, where the eye moves slowly away from a fixation point and then is rapidly corrected through a saccadic (fast) movement. HGN is a type of jerk nystagmus with the saccadic movement toward the direction of the gaze.

An eye normally moves smoothly, whereas an eye with jerk nystagmus moves like a marble rolling across sandpaper. Most types of nystagmus, including HGN, are involuntary motions, meaning the person exhibits the nystagmus without control. The subject exhibiting nystagmus is unaware that it is happening because the bouncing of the eye does not affect the subject's vision.

Law enforcement officers have used field sobriety tests (FST) to detect impairment and to develop probable cause to arrest. Most FSTs test coordination, Balance, and dexterity. The HGN test tracks the movement or coordination and balance of the eye.

The HGN test requires an object for a subject to follow with their eye, such as a pen or the tip of a penlight. The officer places the object approximately twelve to fifteen inches from the subject's face and slightly higher than eye level and instructs the subject to follow the object with the eyes only with the head held still.

The officer checks for the lack of smooth pursuit by eye by moving the object slowly from the center of the subject's face towards the left ear. The left eye should smoothly follow the object, but if the eye exhibits nystagmus, the officer notes the clue. The officer then checks the right eye for the same.

Starting again from the center of the suspect's face, the officer moves the object toward the left ear, bringing the eye as far over as possible and holds the object there for four seconds. The officer notes if there is a distinct and sustained nystagmus at this point. The officer holds the object at maximum deviation for at least four seconds to ensure that quick movement of the object did not cause the nystagmus. The right eye is then checked using the same procedure. The procedure is commonly referred to as “end-point” nystagmus.

The test further requires the officer to move the object at a speed that would take about four seconds for the object to reach the edge of the suspect's left shoulder. The officer notes if the point or angle at which the eye begins to display nystagmus is before the object reaches forty-five degrees from the center of the suspect's face. The officer then moves the object towards the suspect's right shoulder.

Despite the strong correlation between alcohol consumption and HGN, some trial courts still do not admit the results of the HGN test into evidence. Additionally, even if admitted, the officer's administration of the test is often challenged. Therefore, there is a need for an HGN testing device capable of administering and recording the results of an HGN test more consistently and effectively.

SUMMARY OF THE INVENTION

The present invention relates to an HGN testing device capable of administering and recording the results of an HGN test more consistently and effectively.

The apparatus administers the test without human error following a set of accepted protocols for the administration of the test. The apparatus directs various points of light simulating the object an officer would use in directing the test subject to follow with their eyes. The apparatus tests both eyes for the exhibition of nystagmus indicating the subject may be intoxicated.

The apparatus can test and record the eye movement of a test subject for the lack of smooth eye movement in the pursuit of an object. The apparatus further tests for distinct nystagmus at a maximum deviation. Additionally, the apparatus looks at the angle of onset of nystagmus prior to forty-five degrees or when the eye begins to display nystagmus before the object reaches forty-five degrees from the center of the suspect's face.

In great detail, the apparatus for administering a horizontal gaze nystagmus test includes a harness configured to fit a human head such that the apparatus can engage the eyes of the test subject. The harness is typically adjustable and can be configured as either a cap or simply with straps.

In one embodiment, the apparatus uses a jointed armature assembly connected to the harness having a first and second end, wherein the second end includes a distinct terminus. The distinct terminus is the point to which the subject's eyes must follow. In an embodiment the terminus is a small light emitting diode (LED). The apparatus further includes a motor operatively connected and driving the second end of the jointed armature assembly. The device also includes a computing device operatively connected to the motor whereby the movements of the armature assembly can be directed. The computing device may be program logic controller (PLC) capable of directing the armature about a preprogramed path. A power supply is included which is operatively connected to the motor, computing device and light source. The power supply can include a battery.

The apparatus also includes a recording device affixed to the harness whereby the movement of the eyes can be recorded in response to the movement of the distinct terminus end of the armature. The recording device can be selectively detachable to the harness wherein an attachment device is operatively configured to receive and power such a device on the harness. The recording device can capture either visual images, audio signals or both.

A further embodiment includes both a harness and a visor attached to the harness. The visor is operatively aligned in front of the subject's eyes whereby the visor screens the subject's eyes. A projector is included and attached to the harness for displaying a distinct light source onto the visor. The projector can move the light source about an eye facing surface of the visor for the subject's eye to follow. A computing device is operatively connected to the projector whereby the movements of the light source can be directed and a power supply operatively connected to the projector and computing device.

Additionally included in a further embodiment is a display screen attached to the harness and operatively aligned in front of the subject's eyes wherein a distinct point of light is displayed on the screen and visible to the subject's eyes. The apparatus also includes a computing device operatively connected to the screen whereby the movement of the distinct point of light can be directed about the screen and a power supply operatively connected to the screen and computing device. The apparatus can also include a recording device affixed to the harness whereby the movement of the eyes can be recorded in response to the movement of the light sources.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1shows a first exemplary embodiment100of the Horizontal Gaze Nystagmus (HGN) test device according to the present invention. The HGN test device100preferably has a harness110, an armature assembly120driven by a motor142, a recording device152(e.g., an image sensor or video camera), a computing device144, a light150, and a power supply146.

The harness110is preferably configured to be worn about the head12of a test subject10(seeFIG. 3A). The harness110may be adjustable. For example, the harness may have adjustable straps (seeFIG. 3) or an elastic band112as shown.

The armature assembly120preferably includes a plurality of articulated arms (here shown as a first armature member122and a second armature member124) having one or more joints126and extending between a first end130and a second end132. A visual stimulus140is preferably positioned on the second end132and the first end130is preferably operatively connected to the motor142.

The stimulus140may include any object capable of being followed by the human eye. For example, and not by limitation, the stimulus140may be a small pigmented ball mounted to the end of the armature and/or a light source such as a light emitting diode (LED). It is further contemplated that the stimulus140may have various shapes and colors, including objects which luminesce.

The motor142is preferably a servomotor with a rotary actuator (not shown); however, any motor capable of performing the functions as disclosed herein may be used. Additionally, or alternatively, a plurality of motors142may be utilized according to the present invention. A controller is preferably operatively connected to the motor142to control motor direction and/or speed.

The recording device152is preferably attached to the harness110and positioned to record the movement of the subject's eyes16A,16B (seeFIG. 3A) in response to the movements of the stimulus140. The recording device152may be selectively detachable from the harness110through an attachment device154, such as a clip and socket configuration. Of course, other known configurations for attaching the recording device152to the harness110can be used.

The recording device152and/or controller may be configured to store any recordings as an electronically accessible record (such as an image format (e.g., *.tif, *.jpg, *.gif, or *.png file) or encoded video format (e.g., MPEG, H.261, H.263, H.264)) within internal memory storage (not shown) in the recording device (e.g., an SD card) or memory otherwise mounted to the harness110, and/or configured to transmit the electronically accessible record or a copy thereof to an external storage device (e.g., a nonvolatile electronic memory such as a storage medium (server) that is accessible over a network, such as the internet (not shown) via a wired connection and/or wireless transmission (e.g., BLUETOOTH® communication, IEEE 802.11 wireless communication). More preferably, simultaneously with the creation or transmission of the electronically accessible record, or preferably soon thereafter, and as a result thereof, a chain of custody record is created and associated with the electronically accessible record. The chain of custody record preferably includes information related to at least one of, but preferably all of, the following: date of creation of the electronically accessible record, time of creation of the electronically accessible record, geographic location of the creation of the electronically accessible record, a name of a human whose eyes were visually recorded in the electronically accessible record, direction and duration of movements of the stimulus during creation of the electronically accessible record, and/or a name of a human who caused the creation of the electronically accessible record.

The recording device152, when secured to the harness152or otherwise positioned for use with respect to a subject's head, is configured to capture still images and/or video sequences from a focal field of about 5 to about 7 inches wide—but in any event at least as wide as a subject's bizygomatic breadth (maximum horizontal breadth between the zygomatic arches)—by about 1 to about 3 inches tall, at a distance of about 10 to about 18 inches from the stimulus140, measured towards the first end130along a subject's sagittal plane when the harness is mounted thereto.

Additionally or alternatively, the recording device152may record audio and/or other images such as surface temperature through thermal imaging.

The light150(e.g., a diffused light to simply illuminate the face14sufficiently to enable observation and/or recording of eye movement) is preferably attached to the harness110and aimed at the face14of the subject10to illuminate the subject's eyes16A,16B during the administration of the HGN test.

The computing device144is preferably in operative communication with the motor142, the recording device152, and/or the light150. The computing device144is preferably configured to administer the HGN test and operate the recording device152and the light150. The computing device144may be attached to the harness110as shown inFIG. 1or it may be located remotely. The computing device144may be wired to the motor142, the recording device152, and the light150or it may be in wireless communication therewith (e.g., BLUETOOTH® communication, IEEE 802.11 wireless communication).

The power supply146is preferably attached to the harness110and configured to provide power to the motor142, the recording device152, the computing device144(if located on the harness110), and the light150.

The HGN test device100is preferably configured to allow administration of the HGN test pursuant to a method of following a set of protocols. The term “HGN” is used to indicate horizontal gaze nystagmus and the test protocols associated with observing HGN. If the test protocols are modified, the HGN test device100may be programed to include and perform such modifications within the limitations of the hardware of the HGN test device100. It is contemplated that the computing device144is programmable and can be instructed to perform additional tasks as the HGN test evolves.

The device100may be secured at least substantially stationary to a subject's head such that the stimulus140is positioned about ten to about eighteen inches (more preferably about twelve to about fifteen inches) from the subject's nose, and the subject10is instructed to follow the stimulus140with their eyes16A,16B. The HGN test device100is preferably configured to test both eyes16A,16B for the exhibition of nystagmus indicating the subject may be intoxicated.

The HGN test device100is preferably configured to elucidate the three main clues of intoxication under the HGN test. The first is the lack of smooth pursuit of the eye as it follows the stimulus140. During the testing of a subject's left eye16A, the stimulus140moves slowly from the center of the subject's face14(e.g., at least approximately aligned with the sagittal plane of the subject's face) toward the left ear18A (e.g., along a substantially transverse plane), and similarly, for testing the subject's right eye16B, the stimulus140starts at the center of the subject's face14(e.g., at least approximately aligned with the sagittal plane of the subject's face) and moves slowly toward the right ear18B (e.g., along a substantially transverse plane). Preferably, both the left and the right eye16A,16B are tested during the HGN test. If the movement of either of the subject's eyes16A,16B is not smooth in the movement direction of the stimulus140(i.e., pausing, jerking or bouncing) the eye16A,16B exhibits a nystagmus and the person is likely to be intoxicated.

The second test is the discovery of a distinct nystagmus at a set maximum deviation or an end point nystagmus. In this test the subject10is required to follow the stimulus140of the HGN test device100as moves from the center of the subject's face14toward the left ear18A and stops at a predetermined location, typically just within eyesight, and the stimulus140remains in this position for a set period of time, preferably about four seconds. If a distinct and sustained nystagmus is observed in the left eye16A, the subject10is likely to be intoxicated. The same procedure is performed looking for nystagmus in the right eye16B by moving the stimulus140from the center of the subject's face14toward the right ear18B and stopping at a predetermined location, typically just within eyesight, and the stimulus140remains in this position for a set period of time, preferably about four seconds.

The third test includes the detection of the onset of nystagmus prior to reaching a forty-five-degree angle defined from the centerline of the subject's face14and rotating radially toward the subject's left or right shoulder20A,20B. The stimulus140is preferably moved at a constant speed, preferably a speed that would take about four seconds for the stimulus140to simulate an object reaching the edge of a subject's shoulder20A,20B. For the left eye16A, the stimulus140rotates toward the left shoulder20A and for the right eye16B the stimulus140rotates toward the right shoulder20B. Preferably, all three tests are administered to determine if nystagmus is present.

For any of the exemplary embodiments, an indicator (visual and/or audible; not shown) can indicate to the administrator whether the subject passes or fails any of the HGN tests. For example, a green light can indicate the subject10passed the HGN test and is not impaired and a red light can indicate that the subject10failed the HGN test and is likely impaired. A notification of the HGN test results can be sent to the computing device144and stored and/or forwarded to a remote site (not shown), for example, a police station.

Additionally, or alternatively, the HGN test device100may check for vertical nystagmus. Vertical nystagmus may be checked by moving the stimulus140several inches above a subject's eyes16A,16B. While vertical nystagmus is not part of the typical HGN test, it is a good indicator of consumption of high doses of alcohol. The capability to perform such a test may be included in an embodiment of the HGN test device100and in the testing procedures administered to the subject with the HGN test device100.

FIG. 2shows a second embodiment200of the HGN test device. The HGN test device200has a projector220mounted to a harness210preferably configured to project a distinct point of light (not shown) onto a screen222. The harness210illustrated inFIG. 2is a cap design configured to mostly fit about the top of a subject's head12. The screen222is preferably curved and positioned outward from the subject's face14to encompass a substantial portion of the subject's field of vision.

Similar to the first embodiment100, the HGN test device200preferably has a light250for illuminating the subject's eyes16A,16B, a recording device252such as a camera positioned to record movement of the subject's eyes16A,16B mounted to the harness210with an attachment device254, a computing device244, and a power supply246.

The subject is instructed to follow the point of light (not shown) from the projector220with his eyes16A,16B according to the HGN protocol described above. A computing device244controls the projector220and commands the projector220to project the point of light onto the screen222and move the light about the screen222. Preferably, the screen222is transparent from a HGN test administrator's perspective so that the eyes16A,16B of the subject10may be observed. The elements common to those in the first embodiment100may be attached and configured in the same way as applied to second embodiment200.

FIG. 3depicts a third embodiment300of an HGN test device according to the present invention similar to that of the second embodiment HGN test device200shown inFIG. 2. The HGN test device300has a projector320mounted to a harness310preferably configured to project a distinct point of light (not shown) onto a screen322. The harness310illustrated inFIG. 3wraps around a subject's head12and has adjustable straps312configured to be adjustable to provide a secure fit.

The screen322is preferably curved and positioned outward from the subject's face14to encompass a substantial portion of the subject's field of vision. The HGN test device300preferably has a light350for illuminating the subject's eyes16A,16B and a recording device352such as a camera positioned to record movement of the subject's eyes16A,16B and is mounted to the screen322.

FIG. 4illustrates a fourth embodiment400of an HGN test device incorporating the features described above with respect to the third embodiment300(such as a harness410, a projector420, a screen422, a light450, and a recording device452), however, the HGN test device400has a harness410with side members412attached to and extending from the screen422configured to wrap around or be supported by a subject's ears18A,18B.

FIG. 5depicts a fifth embodiment500of an HGN test device according to the present invention. The HGN test device500shown has an electronic display520attached to a harness510, a computing device544, a power supply546. The electronic display520displays a point of light or object (not shown) for the eye16A,16B of the subject10to follow. The displayed point of light functions just as the stimulus140in the first embodiment100and the point of light provided in the second, third, and fourth embodiments200,300,400.

The electronic display520may be comprised of a plurality of LEDs, a liquid crystal display (LCD), or any type of electronic display capable of being mounted to the harness510and functioning in a manner as described herein. Furthermore, the elements common to those in the first embodiment100may be attached and configured in the same way as applied to fifth embodiment500.

FIG. 6provides a sixth embodiment600of the HGN test device. The HGN test device600has a harness610with a visor614and an arm620. The harness610is designed to rest on the subject's head12and to be adjustable with adjustment straps612.

The arm620preferably has a first member622with a first member proximal end624and a first member distal end626and a second member628with a second member proximal end630and a second member distal end632. The first member622preferably extends substantially perpendicular from the face14of a subject10with the first member proximal end624operatively connected with a motor642positioned approximately at the top of the middle of the subject's face14. The second member proximal end630is preferably coupled to the first member distal end626at a junction634, with the second member628extending substantially perpendicular from the first member622and downward from the visor614. The second member distal end632preferably has a stimulus640attached to the second member628at or near the second member distal end632.

The visor614has a track616extending about the near periphery of the visor614in a mostly semi-circular pattern. The arm620is received within the track616preferably at or near the junction634of the first member distal end626and the second member proximal end630. The first member622is preferably configured to extend and contract from the motor642as the arm620traverses the track616.

The stimulus640may be a small pigmented ball and/or a light source such as a light emitting diode (LED) mounted to the second member distal end. Additionally, or alternatively, the stimulus640may comprise a plurality of LED lights stacked in a row along the second member628.

Although not shown inFIG. 6, the HGN test device600may also include a recording device, a light, and a computing device as provided in the description of the first embodiment100.

The foregoing is considered as illustrative only of the principles of the invention. Furthermore, because numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.