Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
2000-02-10
2001-05-15
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
C600S558000
Reexamination Certificate
active
06231187
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a portable apparatus for measuring eye movement of subjects, and to methods for diagnosing and treating neurological disorders using such an apparatus.
BACKGROUND OF THE INVENTION
Information relating to eye movement and eye position is useful for the diagnosis of many neurological conditions, such as dyslexia. A number of devices for obtaining such data have been described, many of which include eye position sensors based on variations of the Purkinje eye tracker, wherein a light beam is applied to each eye and the light reflected from the eyes is used to determine eye position. In a device for measuring eye position described in U.S. Pat. No. 4,889,422, issued Dec. 26, 1989 to Pavlidis, a frame is provided for holding a subject's head, to prevent relative movement between the head and eye position sensors. U.S. Pat. No. 5,070,883, issued Dec. 10, 1991 to Kasahara, relates to an eye movement detecting apparatus to be worn on the head of an individual being tested, to overcome the problem of relative movement between eye position sensors and the head. U.S. Pat. No. 5,305,764, issued Apr. 26, 1994 to Yamada et al., describes a device for measuring eye and head movement of a subject, so that the line-of-sight of an individual may be detected. Further devices are described in U.S. Pat. Nos. 4,373,787, issued Feb. 15, 1983 to Crane, and No. 4,102,564, issued Jul. 25, 1978 to Michael.
The above-mentioned prior art devices are similar in that they provide precise information regarding the position or movement of the eyes themselves. As these devices rely on delicate and sensitive eye position detectors to provide the information, they are complex, and the delicacy of the detectors limits their portability.
Diagnosis of some neurological disorders may not require detailed information regarding eye position. Attention-deficit hyperactivity disorder (ADHD) is one such neurological condition, characterized by inattentiveness, impulsiveness, and hyperactivity. In the diagnosis of ADHD, data relating simply to eye movement would suffice and, in such cases, the above-mentioned prior art devices are not appropriate owing to their complexity of construction and usability.
Moreover, the diagnosis of ADHD, as with any neurological disorder, is ideally carried out with young children, so that corrective measures can begin at an early age. To do this, it would be most advantageous to have a device which could be both portable and inexpensive so that it could be taken to schools to screen children and operated by school personnel after minimal training. However, as mentioned above, existing instrumentation available to test eye movement is usually very expensive, not portable, and difficult to use.
OBJECT OF THE INVENTION
It is an object of this invention to provide a simple, inexpensive, and portable apparatus for diagnosing neurological disorders in individuals on the basis of eye movements.
It is a further object of this invention to provide methods for diagnosing and treating neurological disorders in individuals on the basis of eye movements.
SUMMARY OF THE INVENTION
In a first broad aspect, the invention provides an apparatus for diagnosing a neurological disorder in a subject by detecting the subject's eye movement. The apparatus includes: a helmet for blocking visual stimuli from the subject's visual field; at least one visual cue disposed inside the helmet within the visual field of the subject when the helmet is placed on the subject's head, the visual cue capable of being switched from on to off states; at least two electrodes for attaching to the subject's head, the electrodes producing electrical signals corresponding to the subject's eye movements; signal processing means for controlling on and off states of the visual cues, receiving and processing electrical signals produced by the electrodes, and producing output signals corresponding to the subject's eye movements; and means for displaying output signals produced by the signal processing means.
In a preferred embodiment, the at least one visual cue is at least three visual cues. The at least three visual cues are disposed inside the helmet within the visual field of the subject when the helmet is on the subject's head, and are located at the center, left, and right of the subject's visual field.
The signal processing means and display means may be disposed on the helmet. The signal processing means may comprise: at least one amplifier for amplifying the electrical signals produced by the electrodes; an A/D converter for receiving the output from the amplifier and producing a digital signal therefrom; and logic circuitry for processing the digital signal, controlling illumination of the visual cues, and producing output signals corresponding to the subject's eye movements. In certain embodiments of the invention, the A/D converter is disposed on/in the helmet, and the logic circuitry and display means are separate from the helmet. In the latter case, the logic circuitry and display means comprise a personal computer.
In some embodiments of the invention, at least one sound-emitting device is disposed within the helmet, wherein the sound-emitting device is controlled by the signal processing means. Preferably, two sound-emitting devices are disposed within the helmet, one adjacent each of the subject's ears when the helmet is on the subject's head.
In another broad aspect, the invention provides a method for diagnosing a neurological disorder in a subject. The method includes the following steps: (a) providing at least three visual cues within the subject's visual field while blocking any other visual stimuli from the subject's visual field, the visual cues capable of being switched from on to off states; (b) switching on the central visual cue; (c) switching off the central visual cue and switching on either one of the left or right visual cues; (d) switching off the left or right visual cue and switching on the central visual cue, wherein the subject is instructed to look at the central visual cue and then away from whichever of the left or right visual cues is subsequently switched on; (e) measuring the direction of eye movement in response to the switching on of either the left or right visual cue; (f) determining whether the subject's eye movements were as instructed; (g) repeating steps (b) to (f) a prescribed number of times; and (h) obtaining a score of the total number of correct or incorrect eye movements; wherein the score is diagnostic of the disorder and wherein an apparatus as described above for the first broad aspect of the invention is employed.
In a further broad aspect, the invention provides a method for treating a neurological disorder in a subject. The method includes the following steps: (a) providing visual cues within the left, right, and center of the subject's visual field while blocking any other visual stimuli from the subject's visual field, the visual cues capable of being switched from on to off states; (b) switching on the central visual cue; (c) switching off the central visual cue and switching on either one of the left or right visual cues; (d) switching off the left or right visual cue and switching on the central visual cue, wherein the subject is instructed to look at the central visual cue and then away from whichever of the left or right visual cues is subsequently switched on; (e) measuring the direction of eye movement in response to the switching on of either the left or right visual cue; (f) determining whether the subject's eye movements were as instructed; (g) providing positive reinforcement if the subject's eye movement was correct and/or negative reinforcement if the subject's eye movement was incorrect; and (h) repeating steps (b) to (f) a prescribed number of times. In some embodiments, the method also includes the step of obtaining a score of the total number of correct or incorrect eye movements, wherein reinforcement is provided
Hampton Karen A.
Loeb Gerald E.
Munoz Douglas P.
Ten Hove Martin W.
Manuel George
Miernicki Steeg Carol
Queen's University at Kingston
Scribner Stephen J.
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