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Publication Number
US-8911085-B2
Publication Date
2014-12-16
Expiration Date
Abstract
A method of screening a pupil of a subject to determine whether the pupil reflex resembles a canonical pupil reflex is disclosed. The method comprises the steps of stimulating the pupil with a stimulus source, such as a pupilometer and determining whether one of various pupillary response conditions is met.
Core Innovation
The invention provides a handheld pupilometry system and associated methods in which a pupil of a subject is stimulated by a stimulus source and a pupilometer begins tracking the pupil constriction response when the pupil is stimulated. During the stimulation, the pupilometer collects a plurality of data points, each data point corresponding with a diameter of the pupil at a specific point in time. The data points are compiled into a pupil data profile and used to determine whether the pupil reflex resembles a canonical pupil reflex.
The method determines whether specified conditions are met based on time-resolved pupil diameter behavior during a period in which the pupil is reactive to the stimulus. The conditions include repeated representations of the same pupil diameter at three or more separate points in time within no more than about four seconds, the existence of a first phase of the pupilary reflex response characterized by non-constriction immediately subsequent to stimulating the pupil with a duration less than about 100 msec or greater than about 1000 msec, and timing relationships between two data points representing the same pupil diameter within a specified time window.
The method further includes a condition that during the first phase the diameter of the pupil increases before it decreases. The described hardware/software architecture supports pupil tracking, feature extraction, and analysis of latency and constriction response dynamics, including latency and constriction and dilation velocities, along with pupil irregularity detection and anomaly/statistical rejection.
Claims Coverage
The document provides five independent methods that share a common structure: stimulate the pupil, track the constriction response with a pupilometer beginning at stimulus onset, collect time-stamped diameter data points, generate a pupil data profile, and determine whether multiple quantitative conditions are met; if none are met the output indicates resemblance to a canonical reflex. The inventive features are the quantitative condition set used to classify a reflex as canonical and the time-resolved screening based on the first non-constriction phase and repeated diameter/timing relationships.
Canonical pupil reflex screening from time-resolved diameter profiling
Stimulating the pupil with a stimulus source; using a pupilometer to track the pupil’s constriction response beginning when the pupil is stimulated; collecting a plurality of data points corresponding with a diameter of the pupil at a specific point in time while the pupil is being stimulated; generating a pupil data profile by compiling the data points; and determining whether each of conditions a–d is met so that if none exists an output indicates the pupil reflex resembles a canonical reflex.
Non-constriction first phase characterization and reflex-shape rule
Determining whether a first phase of the pupilary reflex response exists immediately subsequent to stimulating the pupil, characterized by a period of non-constriction with a duration of less than about 100 msec or greater than about 1000 msec, and determining that during the first phase the diameter of the pupil increases before it decreases.
Repeated same-diameter consistency within a defined post-stimulus window
Determining whether more than two data points exist representing the same pupil diameter at three or more separate points in time during a period of no more than about four seconds in a pupil that is reactive to the stimulus.
Two matching diameter points within a defined timing window
Determining whether two data points exist representing the same pupil diameter at two separate points in time in a pupil that is reactive to the stimulus, wherein the two separate points in time are within about 100 msec, or within about 200 msec, or within about 300 msec, or within about 400 msec, or within about 260 msec of each other, depending on the method.
Across the independent claims, the coverage centers on classifying whether a pupil reflex resembles a canonical pupil reflex by using a pupilometer to generate a time-resolved pupil data profile during stimulation and then applying a set of quantitative conditions. The conditions include repeated diameter occurrences within a post-stimulus time window, identification of an initial non-constriction first phase with a specified duration bound, and a rule that the diameter increases before it decreases during that first phase, together with a timing constraint for two matching diameter points.
Stated Advantages
Documented Applications
No documented applications found
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