The Australian National University

Konan Medical USA, Inc.

Teddy Lee Maddess

Andrew Charles James

Corinne Frances Carle

Joshua Paul Van Kleef

Estimating the responses of multiple parts of the visual fields of one or both eyes from records of the responses of one or both pupils to concurrently presented multifocal stimuli to the multiple parts of those visual fields. Collections of multifocal stimuli are controlled by separate pseudo-random sequences, one sequence for each stimulated visual field region. Both temporal impulse responses for each component part of the field and gain-kernels characterizing dynamic changes in the pupil responses driven by short-term fluctuations in overall stimulus density are estimated. Many fewer kernels can be estimated by grouping the stimuli into symbolic stimulus groups and only estimating a gain-kernel for each group. Particular symbolic stimulus groups are shown to be highly efficient. The ability to estimate more reliable responses with relatively few extra gain-kernel coefficients means less data is required to be collected.

Response estimation to efficiently capture dynamic response gain changes in multifocal responses

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 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.

Method and apparatus for sensory field assessment

Systems and methods are disclosed for assessing the function of parts of one or more sensory fields of a subject. Pupillary responses to at least two clustered ensembles of stimuli presented to predetermined portions of the sensory fields to be tested are measured. Each cluster comprises individual stimuli presented at locations across the sensory field, where the locations are defined on appropriate axes for the tested sensory fields. The method comprises: presenting statistically independent sequences of selected individual stimuli from the two or more clustered stimulus ensembles to a sensory field of a subject, thereby evoking pupillary responses in at least one pupil of the subject; detecting responses of the pupil or pupils evoked by the stimuli using at least one sensor; and processing the detected responses to relate the detected response to the sensory function of each component part of the sensory field. The sensory fields may be, but are not limited to, the visual fields of the two eyes of a subject.

Clustered volley method and apparatus

A system and method for assessing the function of parts of the nervous system of a subject by measuring the pupillary responses to at least one stimulus ensemble comprising a plurality of individual stimuli; the method comprising: presenting a sequence of selected individual stimuli from the at least one stimulus ensemble to the nervous system of a subject thereby evoking pupillary responses in at least one pupil of the subject, selected individual stimuli being concurrently presented in the sequence, wherein the individual stimuli are each individually balanced such that the pupillary responses evoked by individual stimuli in the ensemble are balanced according to the strength of the neural responses evoked by the individual stimuli; detecting responses of the pupil or pupils evoked by the stimuli using a sensor; and processing the detected responses to relate them to the function of the subject's neural responses to some or all of the individual stimuli of the ensemble.

Pupillary assessment method and apparatus

The present invention relates to a method and an apparatus for simultaneously assessing the functional status of component parts of the nervous system by presenting sparse stimuli to one or more parts of the sensory nervous system. Sparse stimuli consist of temporal sequences of stimulus conditions presented against a baseline null stimulus condition, where the non-null stimulus condition, or conditions, are presented relatively infrequently. The low probability of encountering a stimulus differing from a baseline or null stimulus condition in sparse stimulus sequences insures that gain control mechanisms within the nervous system will increase the neural response magnitude and also bias the measured responses to those neurone populations having such gain controls. The consequently increased response amplitudes ensure more reliably recorded responses than are obtained with non-sparse stimuli.

Method and apparatus for assessing neural function by sparse stimuli

This invention concerns the detection of neural damage to the optic nerve, optic radiations and white matter of the visual brain indicative of various neurological disorders but with particular application to multiple sclerosis. The method involves simultaneous measurement of the shape and latency of responses to visual stimuli presented simultaneously in different parts of the visual field of the two eyes, separating out linear and nonlinear response components, and most particularly separating out binocular interaction responses to assess neural function within each half of the visual cortex. Because rough retino-topicity is maintained in the optic nerve, through the optic radiations and the visual cerebral cortex, stimulation of the separate parts of the visual field permits isolation of responses from different component parts of these neural elements and therefore from the results obtained an objective assessment of damage to these separate neural components can be made simultaneously.

Simultaneous binocular assessment of multiple optic nerve and cortical regions in diseases affecting nerve condition

Method and apparatus for early detection of glaucoma

A diagnostic test for glaucoma, which can detect the early stages of this disease, uses a pattern electroretinogram of a subject to assess any reduction of the density of M.sub.y ganglion cells in a part of the subject's retina. The visual field of the eye of the subject is divided into a number of zones, and a respective visual stimulus signal is applied to each zone. The visual stimulus signals are generated in accordance with data obtained from determinations of the critical spatial frequency (Nyquist frequency) of persons with normal vision, obtained from observations of the 'aliasing' phenomenon. Typical visual stimulus signals are grating patterns, with the contrast of the signal applied to each zone modulated with a different temporal frequency in the range of from 10 Hz to 45 Hz. Any differences between the electroretinogram response component for an individual zone and the expected response component for that zone indicates a change in the M.sub.y ganglion cell function in that zone, attributable to the effect of glaucoma.

Glaucoma testing using non-linear systems identification techniques

Optokinetic nystagmus is the rhythmical scanning of the eyes when primates attempt to stabilize constantly moving visual scenes. If a pattern having distinct vertical features is projected onto a screen and is drifted to the left or to the right, variations of certain parameters associated with optokinetic nystagmus of a subject observing the drifting pattern from the values of those parameters for persons having normal, healthy vision provide an indication of damage to M-type ganglion cells due to the presence of glaucoma in the subject. Such variations occur at an early stage of glaucoma, before other positive indications of the disease are present. Preferably the projected pattern is a coarse sinusoidal grating with vertical striations, which is temporally modulated by a rapid movement or flicker.

Glaucoma testing from observations of optokinetic nystagmus

Existing techniques for diagnosis of glaucoma, namely observation of a scotoma, measurement of intraocular tension and assessment of color vision defects have drawbacks. The present invention overcomes those drawbacks by a psychophysical test in which a sinusoidal grating pattern is presented to a subject with the contrast of the pattern modulated at a frequency in the range from about 10 Hz to about 50 Hz, so that the subject can observe a frequency-doubled pattern of the grating. The contrast of the pattern is then reduced until a threshold value is reached, at which value the frequency-doubled pattern is no longer observed. The threshold value is then compared with the threshold value for persons of normal vision. A higher than normal threshold value indicates that the subject may be suffering from glaucoma. Persons with well-developed glaucoma have threshold values that are approximately twice the threshold value of a person with healthy vision. The pattern is conveniently established on the screen of a cathode ray tube, controlled by a programmed microprocessor.

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Lyneham, Australia

Teddy Lee Maddess