Visual electrophysiology device

摘要

To assess visual system function, a device monitors electrical response to a visual stimulus. Stimulus generation includes controlling the timing of component flashes comprising the visual stimulus and modulating the timing between the visual stimulus and other device operations, including image acquisition and infrared flashes. Other stimulus generation includes controlling retinal illumination for sinusoidal, triangular, and square stimuli as well as nonlinear adjustments of stimulus luminance as a function of pupil area. Ease of use improvements includes operation with electrode arrays. Error condition monitoring includes determining the presence of: an eye's pupil; impedance between electrodes that monitor the electrical response; and undesirable levels of external light.

主权项

1. A device providing an indication of visual system function of a patient comprising:
a. a first light emitter having a visible first emission spectrum; b. an optical assembly arranged so that light emitted from the first light emitter reaches an eye of the patient; c. a camera arranged to image the eye of the patient; and d. a controller that modulates a light emission from the first light emitter to create a light stimulus, that receives and analyses an electrical signal from the visual system of the patient and that provides an indication of visual system function based on that analysis, wherein the device is further modified so that one or more of the following conditions applies:
(i) the device further comprises a second light emitter having a visible second emission spectrum that is distinct from the first emission spectrum, wherein:
the optical assembly is arranged so that light emitted from the second light emitter reaches an eye of the patient,the controller measures the eye's pupil area using images from the camera and adjusts the luminance of light stimulus as a function of the eye's pupil area, andthe controller modulates light emission from the first and second light emitters to create first and second flashes overlapping in time by at least 50% of the longer of the two flashes;(ii) the light stimulus comprises one or more flashes of light and the controller synchronizes the camera and the light stimulus so that the camera is only activated when there is no flash;(iii) the controller measures the eye's pupil area using images received from the camera and adjusts the luminance in the light stimulus through a non-linear, concave function of the eye's pupil area;(iv) the controller does not provide an indication of visual system function unless the eye's pupil has been identified;(v) the device further comprises a light detector adapted to measure light emitted from the first light emitter, wherein the controller does not provide an indication of visual system function if the signal from the light detector differs from a set of expected light detector signals that includes excessive external light;(vi) the device further comprises:
an electrode array comprising three electrodes structurally adapted to be applied and removed from the skin as a single unit;an analog to digital converter that measures the electrical signal equal to the electric potential difference between a first electrode and a second electrode in the electrode array; anda common-mode attenuation circuit electrically connected to a third electrode in the electrode array, wherein the distance between the first and second electrode is greater than the distance between the first electrode and third electrode and the distance between the first and second electrode is greater than the distance between the second electrode and third electrode;(vii) the controller modulates a light emission from the first light emitter so as to deliver to the eye a periodic light stimulus that approximates a retinal illuminance that varies as one of a sinusoid, a square wave having a duty cycle between 30% and 70%, or a triangular wave; and(viii) the device further comprises an infrared light emitter having an emission spectrum that has at least 50% of its energy emitted at wavelengths longer than 710 nm, wherein:
the optical assembly is further arranged so that light emitted from the infrared light emitter reaches the eye,the controller modulates a light emission from the infrared light emitter to create an infrared flash of light having a duration less than 40 ms, andthe energy emitted by the first light emitter during the infrared flash of light is less than 50% of the energy emitted by infrared light emitter during the infrared flash of light.