Method and Apparatus for Sensory Field Assessment

• US 20100249532A1
• Filed: 11/07/2008
• Published: 09/30/2010
• Est. Priority Date: 11/09/2007
• Status: Active Grant

• Current Assignee: KONAN MEDICAL USA, INC.
• Original Assignee: KONAN MEDICAL USA, INC.
• Inventors: James, Andrew Charles, Maddess, Teddy Lee
• Granted Patent: US 10,064,548 B2
• Time in Patent Office: Days
• US Class Current: 600/300
• CPC Class Codes: A61B 3/024 for determining the visual field, e.g. perimeter types
• CPC Class Codes: A61B 5/378 Visual stimuli

Abstract

A method for assessing the function of at least one sensory field of a subject, and apparatus and systems for carrying out the method, the method comprising: using a display, presenting stimuli to selected locations of the sensory field, the selected locations being centred at points on a sampling grid spanning a portion of the sensory field, wherein the individual stimuli if presented simultaneously at the sampling grid points would overlap in the space defined by the sensory dimensions of the field; using a sensor, detecting responses in the subject'"'"'s sensory field evoked by the stimuli; and processing the detected responses to relate them to the function of the subject'"'"'s sensory field at the selected locations.

Claims

1-59. -59. (canceled)

60. A method for assessing the function of the sensory field of a subject, the method comprising:

presenting stimuli to selected locations of the sensory field, the selected locations being centered at points on a sampling grid spanning a portion of the sensory field, wherein the individual stimuli if presented simultaneously at the sampling grid points would overlap in the space defined by the sensory dimensions of the field;

using a sensor, detecting responses in the subject'"'"'s sensory field evoked by the stimuli; and

processing the detected responses to relate them to the function of the subject'"'"'s sensory field at the selected locations.

61. A method as claimed in claim 60 wherein the stimuli, if presented simultaneously, are sufficiently overlapping such that spatial aliasing of the stimuli on the sampling grid is minimized.

62. A method as claimed in claim 60 wherein the profiles of the stimuli are smoothly varying such that the individual stimuli comprise mainly spatial frequencies that are about less than or equal to the highest spatial frequency that can be represented by the sampling grid.

63. A method as claimed in any one of claim 60 wherein the sensory field has a horizontal meridional axis and a vertical meridional axis, and the stimuli do not overlap with either the vertical or horizontal meridional axes of the sensory field.

64. A method as claimed in claim 63 wherein the stimuli are chosen such that, in use, each stimulus stimulates approximately equal numbers of sensory neurons in the sensory field.

65. A method as claimed in claim 60 wherein the sampling grid is presented in a polar representation wherein the coordinates of the polar representation may be linear or nonlinear functions of radius and polar angle.

66. A method as claimed in claim 60 wherein the stimuli are presented so as to produce a perception of a spatially frequency doubled arrangement such that the perceived spatial frequencies are between 30% lower than frequency doubled frequencies and 200% of the frequency doubled frequencies.

67. A method as claimed in claim 60 wherein the responses in the subject'"'"'s sensory field evoked by the stimuli are detected by a method selected from the group of:

detecting electrical potentials by detecting changes in magnetic;

or electromagnetic radiation;

by detecting changes in acoustic signals;

by detecting changes in the responses of the subject'"'"'s pupil;

or by detecting changes in movements of the subject'"'"'s eye, or a behavioral response of the subject.

68. A method as claimed in claim 60 wherein the stimuli are presented either successively or concurrently.

69. A method as claimed in claim 60 wherein the stimuli are presented in a multifocal arrangement wherein the processing comprises the step of computing linear and/or nonlinear weighting functions that characterize the response of each stimulated portion of the sensory field stimulated by the stimuli.

70. A method as claimed in claim 69 wherein the concurrently presented stimuli are temporally sparsely presented.

71. A method as claimed in claim 69 wherein the concurrently presented stimuli are spatially sparsely presented.

72. A method as claimed in claim 69 wherein the concurrently presented stimuli are sparsely presented both spatially and temporally.

73. A method as claimed in claim 71 wherein two or more spatially sparse stimuli are presented simultaneously.

74. A method as claimed in claim 60 wherein the stimuli are presented at locations on a multi-dimensional sampling grid.

75. A method as claimed in claim 60 wherein the stimuli are presented at locations on a regular sampling grid.

76. A method as claimed in claim 60 wherein the stimuli are presented at locations on an irregular sampling grid.

77. A method as claimed in claim 60 further comprising the step of enhancing generally elongated features within a polar representation of the stimulus space by operation of one or more filters having an aspect ratio of about 3 to 1 wherein the one or more filters may be edge preserving filters.

78. A method as claimed in claim 77 wherein the processing comprises transforming the measured responses to a rectilinear representation of the stimulated portions of the sensory field.

79. A method as claimed in claim 60 wherein the processing comprises the step of transforming the measured responses to a polar representation of the stimulated portions of the sensory field.

80. A method as claimed in claim 60 wherein the sensory field under assessment is selected from the group of at least one visual sensory field, at least one auditory sensory field, or a tactile sensory field of the subject.

81. A method as claimed in claim 60 wherein the sensory field under assessment is two or more sensory fields selected from the group of at least one visual sensory field, at least one auditory sensory field, and a tactile sensory field of the subject.

82. A method as claimed in claim 81 wherein the sensory field under assessment is a plurality of dimensions, each dimension being selected from the group one or two visual sensory fields, one or two auditory sensory field, and one or more tactile sensory fields of the subject.

83. A method as claimed in claim 60 wherein the sensory field under assessment is at least one visual sensory field of the subject encompassing the visual field sensitivity of one or both retinas of the subject.

84. A method as claimed in claim 73 wherein the method of assessing the visual sensory field of one or both retinas of the subject is a method for diagnosing a condition causing visual impairment especially visual impairment localized to a part of the sensory fields.

85. A method as claimed in claim 84 wherein the condition is one or more of glaucoma, age-related macular degeneration, diabetic retinopathy, stroke or multiple sclerosis.

86. An apparatus for assessing the function of the sensory field of a subject, the apparatus comprising:

a display for presenting stimuli to selected locations of the sensory field, the selected locations being centered at points on a sampling grid spanning a portion of the sensory field, wherein the individual stimuli if presented simultaneously at the sampling grid points would overlap in the space defined by the sensory dimensions of the field;

a sensor for detecting responses in the subject'"'"'s sensory field evoked by the stimuli;

a processor for processing the detected responses to relate them to the function of the subject'"'"'s sensory field at the selected locations.

87. An apparatus as claimed in claim 86 wherein the stimuli, if presented simultaneously, are sufficiently overlapping such that spatial aliasing of the stimuli on the sampling grid is minimized.

88. An apparatus as claimed in claim 86 wherein the edges of the stimuli are smoothly varying such that the individual stimuli comprise only low spatial frequency Fourier components and so contain only spatial frequencies that are less than or equal to the highest spatial frequency that can be represented by the sampling grid.

89. An apparatus as claimed in claim 86 wherein the stimuli are chosen such that, in use, each stimulus stimulates approximately equal numbers of sensory cells in the sensory field.

90. An apparatus as claimed in claim 86 wherein the apparatus is adapted for presentation of the sampling grid in a polar representation wherein the coordinates of the polar representation may be linear or nonlinear functions of radius and polar angle.

91. An apparatus as claimed in claim 86 further comprising one or more filters for enhancement of generally elongated features with the polar sampling grid wherein the one or more filters are edge preserving filters.

92. An apparatus as claimed in claim 86 for computing linear and/or nonlinear weighting functions that characterize the response of each stimulated portion of the sensory field stimulated by the stimuli.

93. An apparatus as claimed in claim 86 wherein the wherein the apparatus is adapted for assessment of the visual field sensitivity of one or both retinas of the subject and the displays are selected from the group of a CRT, LCD, plasma, LED, or OLED image display screen or projector.

94. An apparatus as claimed in claim 86 wherein the sensor for detecting responses evoked by the stimuli is a sensor for detecting neural or behavioral responses from the subject.

95. An apparatus as claimed in claim 86 further comprising a memory for recording the responses.

96. An apparatus claimed in claim 86 wherein the stimuli are presented so as to produce a perception of a spatially frequency doubled arrangement such that the perceived spatial frequencies are between 30% lower than frequency doubled frequencies and 200% of the frequency doubled frequencies.

97. An apparatus as claimed in claim 86 wherein the apparatus is adapted for the assessment of a condition causing impairment of the subjects visual fields including any one or more of glaucoma, age-related macular degeneration, diabetic rectinopathy, stroke or multiple sclerosis affecting one or both eyes of the subject.

98. Use of the apparatus of claim 86 for assessment of one or more sensory fields of a subject.