An improved system and method for screening of hepatic encephalopathy by visual perception ability

Abstract

A system for screening hepatic encephalopathy (HE) based on critical flicker fusion frequency (CFFF) detection using visual perception thresholds. The system comprises a frequency setter module that generates a controlled sequence of flickering light signals, an internal oscillator for precise timing, and a frequency tracker module that adjusts the flicker rate based on patient feedback. A frequency re-setter module ensures visual memory effects are minimized by introducing a non-flickering baseline between steps. The system includes a light controller that emits spectrally filtered, intensity-calibrated light optimized for retinal sensitivity. A patient feedback input module records flicker perception responses, while a recording module logs test parameters and outcomes. A secure communication module transmits this data to a remote interface for clinical evaluation. The system dynamically adapts to patient input, enhancing accuracy in determining CFFF, a validated biomarker for minimal HE, thereby enabling early, objective, and non- invasive screening of cognitive dysfunction.

Description

[0001] AN IMPROVED SYSTEM AND METHOD FOR SCREENING OF

[0002] HEPATIC ENCEPHALOPATHY BY VISUAL PERCEPTION ABILITY

[0003] FIELD OF THE INVENTION:

[0004] This invention relates to the field of biomedical engineering.

[0005] Particularly, this invention relates to an improved system and method testing reduction in visual perception ability in distinguishing flicker caused by hepatic encephalopathy vide cFFF.

[0006] Specifically, this invention relates to an improved system and method for screening of hepatic encephalopathy by visual perception ability.

[0007] BACKGROUND OF THE INVENTION:

[0008] Critical flicker fusion frequency (cFFF) refers to the frequency at which a regularly recurring change of light stimuli is perceived as steady. The cFFF threshold is often assessed in clinics to evaluate the temporal characteristics of the visual system, making it a common test for eye diseases.

[0009] There are following parameters that determine the ability to detect the flicker:

[0010] A. External environmental parameters

[0011] 1. Dark adaption - The duration and intensity of previous exposure to background light, which affects both the intensity sensitivity and the time resolution of vision.

[0012] 2. Room conditions - Ability of the test setup to filter any ambient light that may interfere with perception. 3. Dimension and Distance of Stimulus from the eye of observer - The larger dimension with shorter distance creates more conical angle at the eye, which affects ability to perceive stimuli.

[0013] B. Stimuli Parameters

[0014] 1. Actual frequency of modulation of stimuli, its controllability and variance.

[0015] 2. The amplitude of modulation - it is the change in the level of intensity with respect to maximum intensity.

[0016] 3. The Wavelength of Light modulation source - as the human eye has been tuned to only a small range of wavelength for most effective response.

[0017] 4. The modulation ratio- This is the ratio of the duty cycle that the light is modulated to create the actual frequency. Even for a known frequency, increase in duty cycle of waveform will result in different perception threshold.

[0018] C. Subject / Observer related parameters

[0019] 1. The position of retina and balance of perception between two eyes while observation.

[0020] 2. Physiological parameters like overall age and fatigue - both physical and mental. (This is directly affected by level of sleep deprivation and nutritional intake in past 24 hours).

[0021] 3. Macular function of the observer is the ability to actually perceive the light stimuli of flicker in spite of being in healthy conditions.

[0022] 4. Neurological factors like the nerve conduction ability to communicate stimuli to the brain and reset retina cones and rods for next set of inputs. According to prior arts, the devices which administer this test has critical shortcomings:

[0023] • It needs a trained person for administration so the number of patients covered is low. The patient has to physically travel to a hospital or clinic to get this test done.

[0024] • It is difficult for patients to comprehend the meaning of light flicker and the application settings and usage needs an experienced doctor.

[0025] The test takes too long for a patient and has to perform tests multiple times in order to find correct threshold. A patient’s / user’s eye(s) gets used to a particular flicker and they keep seeing it for a long time and such training effect may mislead actual results.

[0026] • Furthermore, the prior art devices have a frequency-to-frequency transition as a sudden or incremental step. So, when small flicker is changed, it remains unnoticeable - this occurs due to persistence of vision / illusion effect; where, eyes get trained for that frequency. Thus, the patient’s / user’s brain expects a similar response and a random flicker goes unnoticed; thereby, the correlative cFFF score may not be true.

[0027] According to prior arts, a cFFF test can take around 2 minutes.

[0028] FIGURE la illustrates prior art’ s logic of ascending frequency - from 25 Hz to 50 Hz.

[0029] FIGURE lb illustrates prior art’s logic of descending frequency - from 50 Hz to 25 Hz.

[0030] Prior art mechanisms have each step covered and ascends / descends from starting frequency to ending frequency passing through each step. Assuming Starting frequency = 25 Hz

[0031] Ending frequency = 50Hz

[0032] Each step = 1 Hz

[0033] Step delay = 5 seconds.

[0034] Total maximum time taken for a test = 25 X 5 = 125 seconds; which is ~2 minutes. cFFF score may not always be maximum.

[0035] For ascending from 25 Hz, Normal Test time = [cFFF score - 25] X step delay

[0036] For descending from 50 Hz, Normal Test time = [50 - cFFF score] X step delay

[0037] OBJECTS OF THE INVENTION:

[0038] An object of the invention is to provide an improved system and method for measurement of visual perception ability vide cFFF.

[0039] Another object of the invention is to provide a system and method for determining accuracy of cFFF threshold vide cFFF such that even if a small change in frequency is observable by patients and such results should be captured by the system and method.

[0040] Yet another object of the invention is to overcome issues of misleading results caused by persistence of vision while evaluation of perception ability vide cFFF.

[0041] SUMMARY OF THE INVENTION:

[0042] According to this invention, there is provided an improved system for screening of hepatic encephalopathy by visual perception ability, said system comprising: a. a frequency setter module configured to generate a sequence of flickering light signals by defining a starting frequency, an ending frequency, an increment between successive frequencies, and a hold duration at each frequency; b. a core electronics module comprising an internal clock-based oscillator, wherein the oscillator generates timing signals to control the sequence without requiring external timing integrated circuits; c. a frequency tracker module configured to sequentially modulate the flicker frequency of the light signals in discrete ascending or descending steps based on patient feedback; d. a frequency re-setter module configured to reset the light output to a non-flickering baseline between successive steps to eliminate visual memory effects; e. a light controller element (LCE) configured to emit spectrally filtered and intensity-calibrated light optimized for human retinal sensitivity; f. a patient feedback input module configured to detect a response indicating perception or non-perception of flicker; g. a recording module configured to log timestamps, flicker frequencies, and corresponding patient responses; and h. a communication module configured to securely transmit the logged data to a remote user interface, wherein the system is configured to dynamically adapt the frequency sequence based on detected patient feedback to improve accuracy of the critical flicker fusion frequency determination. In at least an embodiment, the frequency tracker module is further configured to modify the increment between successive frequencies dynamically based on realtime patient responses, thereby optimizing the flicker frequency sequence for individual patients.

[0043] In at least an embodiment, the light controller element emits light in a wavelength range between most prominent visual wavelength band of light ranging from 450 nanometers and 650 nanometers to optimize stimulation of human cone photoreceptors.

[0044] In at least an embodiment, the communication module transmits the logged data using an encrypted wireless communication protocol selected from Bluetooth Low Energy (BLE) with proprietary security extensions or Wi-Fi Protected Access 3 (WPA3).

[0045] According to this invention, there is provided a method for screening of hepatic encephalopathy by visual perception ability, said method comprising: a. emitting flickering light to the subject at a starting frequency using a spectrally filtered and intensity-calibrated light source; b. incrementally adjusting the flicker frequency in discrete ascending or descending steps based on real-time subject feedback; c. resetting the light source to a non-flickering baseline between successive steps to achieve flicker fusion threshold faster; d. detecting subject responses indicating perception or non-perception of flicker at each frequency step; e. recording timestamps, corresponding flicker frequencies, and subject responses; and f. transmitting the recorded data securely to a remote computing device for analysis, wherein the increment between successive frequencies is dynamically adapted based on detected subject feedback to enhance measurement accuracy.

[0046] In at least an embodiment, the method further comprises dynamically adjusting the flicker frequency increment based on previous subject feedback to fine-tune the frequency sequence towards the critical flicker fusion frequency threshold.

[0047] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0048] FIGURE la illustrates prior art’s logic of ascending frequency - from 25 Hz to 50 Hz; and

[0049] FIGURE lb illustrates prior art’s logic of descending frequency - from 50 Hz to 25 Hz.

[0050] The invention will now be described in relation to the accompanying drawings, in which:

[0051] FIGURES 2 and 3 illustrates a schematic block diagram of this invention;

[0052] FIGURE 4a illustrates current invention’ s logic of ascending frequency - from 25 Hz to 50 Hz;

[0053] FIGURE 4b illustrates current invention’s logic of descending frequency - from 50 Hz to 25 Hz;

[0054] FIGURE 5 illustrates a fast-changing mechanism used in conjunction with this invention’s system and method; and

[0055] FIGURE 6 shows that any value can be achieved within ~30 seconds. DETAIUED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

[0056] According to this invention, there is provided an improved system and method for screening of hepatic encephalopathy by visual perception ability.

[0057] FIGURES 2 and 3 illustrates a schematic block diagram of this invention.

[0058] In at least an embodiment, the system comprises a frequency setter module (FST) configured to determine parameters of frequency. Parameters of frequency include: starting frequency, ending frequency, steps between frequencies, duration of holding on to a frequency, and total time of test optimization factors frequency changes in a pre-determined discrete manner such that the changes are discretely incremental traceable and measurable in nature. The human visual system perceives flicker differently depending on ambient lighting, individual fatigue, and age. To obtain accurate critical flicker fusion frequency (cFFF) thresholds, it is crucial to systematically control starting and ending frequencies, as well as hold durations at each step to allow for retinal adaptation. Setting discrete increments avoids ambiguous perceptual transitions and helps measure thresholds precisely without relying on continuous ramping (which introduces fatigue and errors). This module solves issues relating to prior art systems which used continuously ramping frequencies, causing perceptual adaptation and subjective drift in flicker perception.

[0059] In preferred embodiments, the system comprises a core electronics module which has inbuilt logic and algorithms to generate frequency. There is no external Timer IC used; being inherent, there is no chance of time being drifted over longer durations. Hence once measured during calibration, time interval can be extrapolated for different frequencies. Using an internal clock-based precision generator ensures high frequency stability needed to finely resolve small perceptual differences in cFFF testing. Eliminating external timing components reduces systematic timing jitter, leading to more reproducible results across different environments. This module solves issues relating to prior art systems which had external timer-based systems and caused jitter and drift, making high- accuracy cFFF testing unreliable across different test setups.

[0060] In preferred embodiments, the system comprises settings and user interface module, which remembers settings and other parameters related to patients, time recording, interactive indication and user inputs for actions to decide start and stop of tests and saving and printing when required.

[0061] In at least an embodiment, the system comprises a frequency tracker module (FTT) configured to determine frequency change in a discretely incremental ascending manner or in a discretely incremental descending manner. The light frequency is changed by fixed value after each response so each user has to pass through each frequency sequentially. Discrete steps, with feedback gating, leverage subjective perception timing to personalize the protocol dynamically. Ascending or descending frequency changes at fixed steps (e.g., +1 Hz) allow for mapping the threshold more reliably than free-running frequencies. Dynamic feedback allows early stopping (shorter test duration) and adaptive step sizing based on subject responses, reducing visual fatigue and improving precision. This module solves issues relating to prior art systems wherein static protocols did not account for patient variability, leading to unnecessary testing time and increased cognitive load on subjects. In at least an embodiment, the system comprises a frequency re-setter module (FRT) configured to reset frequency to zero after each change (ascending or descending) in order to achieve discrete increments of values. Thus, frequency changes are as per dynamic time delays. The persistence of vision (1 / 16th of a second) can cause "ghost" flicker effects, biasing subsequent frequency perception.

[0062] Resetting to a baseline (non-flickering light) between steps forces a "visual refresh" in the brain’s visual cortex (V1 / V2 processing areas). This ensures that each frequency presentation is perceived independently and reduces memory effects between sequential steps. This module solves issues relating to prior art systems wherein no resetting led to inaccurate threshold determination because prior flicker perception contaminated current perception.

[0063] There are two modes of operation. In a default mode the step size is 1 Hz and is uniform but in fast seek type mode, a binary sort type jumping is adopted where jump size is initially 10 and keeps reducing or becoming half (rounded off to higher natural number) as the system approaches threshold.

[0064] The intensity is function of available voltage and current. It is independent of frequency of flicker. Actual turning on - turning off of an LED is in the range of few ns and flicker frequency is in the range of few Hz. So, persistence of vision which is subjective and human eye dependent is the only delay in perception of flicker for any person. As voltage is 5V and current provided through a resistor value of 220 Ohms, the current is fixed and hence the intensity is fixed.

[0065] The emitted light intensity is fixed and constant throughout the length of test. Intensity changes will have changes in perception of flicker and will not give expected CFF threshold. In at least an embodiment, the system comprises of Patient Feedback Input (PFI) which is used to record patient input directly in relation to detection of a flicker, before effecting a subsequent change per frequency setting (FST), per frequency re-setter (FRT), and recording modules. In preferred embodiments, the system comprises electronics’ module to record patient feedback and this module is in scanning mode. It also keeps track of frequency changes and accordingly matches user feedback with frequency of modulation. Accurate cFFF measurement depends on real-time subject feedback because flicker perception is subjective and influenced by momentary conditions. Using manual input (button press) or automated detection (e.g., eye movement sensors) minimizes false positives / negatives. Feedback gated stepwise transitions minimize cognitive overload and reduce errors associated with passive continuous measurement. This module solves issues relating to prior art systems wherein systems that lacked immediate feedback relied on end-of-test surveys or delayed inputs, introducing recall bias. Time-correlated data (frequency vs. response) enables precision curve fitting (e.g., psychometric functions) for objective threshold calculation rather than subjective visual estimation. Logging raw timestamped data allows longitudinal tracking (e.g., monitoring progression in diseases like hepatic encephalopathy, where cFFF decline is an early marker). The recording module solves issues relating to prior art systems wherein systems without raw data storage were incapable of retrospective analysis or machine-leaming-based refinement of thresholds.

[0066] In at least an embodiment, the system comprises a LCE (Light Controller Element) which is actual output and is designed to provide outputs as per logic designed and filter all the variants which may affect the ability to perceive flicker and hence keeping all the other parameters same. Retinal photoreceptors (cones and rods) have peak sensitivity at certain wavelengths. Emitting in a narrowband range optimizes flicker perception because it targets maximum cone sensitivity, improving measurement resolution. Calibrating intensity ensures that variations in light output do not confound the flicker detection threshold (since brighter or dimmer lights affect cFFF perception). This module solves issues relating to prior art systems wherein variable intensity and wavelength caused inconsistency across different devices and lighting conditions.

[0067] Typically, a square wave is used to drive light source.

[0068] ON-OFF duration is same; so, duty cycle is 50%.

[0069] ON Time / (Total Time per cycle) = i

[0070] OFF Time / (Total Time per cycle) = Vi

[0071] The control is ON-OFF mode and no PWM is used.

[0072] PWM would create an error in ON time or OFF time of the cycle.

[0073] Duty Cycle is 50%.

[0074] Increasing Duty cycle would bias the perception towards fusion and reducing duty cycle would bias the perception towards flicker of the light.

[0075] In at least an embodiment, the system comprises a communicator module, which is designed to communicate between dedicated hardware and user interfaces, on a fixed proprietary protocol and hence can be done locally or remotely as per need of the device. Patient data security is critical in clinical-grade devices. Encrypted communication (e.g., BEE + proprietary protocol) ensures that clinical data is protected during wireless transmission. Real-time transmission supports remote testing, opening applications in telemedicine and decentralized trials. This module solves issues relating to prior art systems wherein prior art often used unsecured serial communication, risking privacy breaches. This configuration ensures that there is a positive response from a user at that frequency before moving a subsequent (ascending or descending) frequency; thereby, eliminating false negatives / false positives - rendering an accurate, efficient, cFFF score.

[0076] FIGURE 4a illustrates current invention’s logic of ascending frequency - from 25 Hz to 50 Hz.

[0077] FIGURE 4b illustrates current invention’s logic of descending frequency - from 50 Hz to 25 Hz.

[0078] FIGURE 5 illustrates a fast-changing mechanism used in conjunction with this invention’s system and method.

[0079] With fast-changing mechanism,

[0080] Maximum number of steps = 6

[0081] Maximum time needed = 6 X Step delay = 30 seconds = 1 / 2 minutes

[0082] Total Maximum Number of Steps reduced to 6 for resting according to this invention.

[0083] A time saving of 12 minutes per patient can be achieved which is extremely valuable for doctor and patient.

[0084] FIGURE 6 shows that any value can be achieved within ~30 seconds. In this device, suitable height and angle adjustment of viewing chamber is possible for all patients

[0085] The device, of this invention, is portable.

[0086] • Length - end to end 45 cm

[0087] • Maximum Height from bottom - 22cm front

[0088] • Angle Min = - 30 deg to 35 deg

[0089] • Height of patient above Table - can be from 10 cm to 45cm

[0090] • Eye piece can come almost touching to face unlink other existing

[0091] Larger number of patients can be covered as the current invention’s device is transportable and can reach a patient’s home. The test can be performed at home with online and remote support of healthcare professional. The data storage and record keeping is taken care through an application. Time of test is shorter and dynamic algorithm ensures quick reaching to threshold frequency.

[0092] TECHNICAL ADVANTAGES:

[0093] • The test can be remotely administered. It has functionality to control the test as per patient’s feedback. This helps a healthcare professional to reach and test for a large number of patients

[0094] • The device is available with the patient.

[0095] • Record keeping easy direct Bluetooth printer is integrated

[0096] • No calibration is needed

[0097] • Frequency changes are as per dynamic time delays (specialized algorithms)

[0098] • No need of separate power supply, it takes necessary power from TAB / mobile Suitable height and angle adjustment of viewing chamber is possible for all patients.

[0099] The interrelation, between various modules, as disclosed above, of this invention, produces a synergistic technical effect (faster, more accurate, fatigue-reduced cFFF testing).

[0100] The TECHNICAL ADVANCEMENT, of this invention, lies in providing a novel and non-obvious improvement over existing cFFF testing systems by introducing a dynamic, patient-responsive frequency modulation mechanism that eliminates the drawbacks associated with persistence of vision, training effect, and prolonged test durations. Unlike prior art, which relies on linear, fixed-interval frequency increments requiring extensive time and manual administration, the invention introduces a fast-changing, discrete increment mechanism controlled by patient feedback, reducing testing time from approximately two minutes to under thirty seconds. Additionally, the integrated system comprising a frequency setter (FST), frequency tracker (FTT), frequency re- setter (FRT), patient feedback input (PFI), light controller element (LCE), and communicator module, operating through proprietary internal logic without the need for external timing ICs, provides improved accuracy, efficiency, and portability. The ability to remotely administer the test, adjust the device ergonomically for each patient, and maintain automatic electronic record-keeping further distinguishes the invention from known methods and devices, thereby advancing the field of visual perception measurement and screening for conditions such as hepatic encephalopathy. Flicker frequency increment is achieved by a binary sort type algorithm to reach to the result with minimal decision-making jumps. Thus, the jump size and direction depend on the response from the patient.

[0101] According to a non-limiting exemplary embodiment, the following tabulated comparative data shows importance of “Resetting Light to Non-Flicker Baseline

[0102] Between Steps”:

[0103] INFERENCE:

[0104] Without returning to a baseline, the human visual system’ s temporal adaptation reduces sensitivity to changes in flicker rate (due to temporal summation effects). Resetting the stimulus resets retinal and cortical processing, ensuring each new stimulus is detected freshly.

[0105] According to a non-limiting exemplary embodiment, the following tabulated comparative data shows importance of “Spectrally Filtered Light (450-650 nm

[0106] Range) vs. Unfiltered Light”:

[0107] INFERENCE:

[0108] The 450-650 nm band overlaps peak sensitivity curves for human cone photoreceptors. Emitting unnecessary UV / IR light leads to heat generation, discomfort, and receptor cross-activation (particularly rods), all of which degrade flicker perception fidelity. According to a non-limiting exemplary embodiment, the following tabulated comparative data shows importance of “Dynamic Frequency Adjustment Based on Real-Time Feedback vs. Static Frequency Steps”:

[0109] INFERENCE:

[0110] Psychophysical thresholds (like cFFF) are better estimated by adaptive staircase methods (e.g., transformed up-down procedures) than by fixed incremental changes. Adaptive adjustment reduces noise and speeds up convergence to perceptual thresholds.

[0111] While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Claims

CLAIMS,1. An improved system for screening of hepatic encephalopathy by visual perception ability, said system comprising: a. a frequency setter module (FST) configured to generate a sequence of flickering light signals by defining a starting frequency, an ending frequency, an increment between successive frequencies, and a hold duration at each frequency; b. a core electronics module comprising an internal clock-based oscillator, wherein the oscillator generates timing signals to control the sequence without requiring external timing integrated circuits; c. a frequency tracker module (FTM) configured to sequentially modulate the flicker frequency of the light signals in discrete ascending or descending steps based on patient feedback; d. a frequency re-setter module (FRT) configured to reset the light output to a non-flickering baseline between successive steps to eliminate visual memory effects; e. a light controller element (LCE) configured to emit spectrally filtered and intensity-calibrated light optimized for human retinal sensitivity; f. a patient feedback input module (PFI) configured to detect a response indicating perception or non-perception of flicker; g. a recording module configured to log timestamps, flicker frequencies, and corresponding patient responses; and h. a communication module configured to securely transmit the logged data to a remote user interface,wherein the system is configured to dynamically adapt the frequency sequence based on detected patient feedback to improve accuracy of the critical flicker fusion frequency determination.

2. The system as claimed in claim 1 , wherein the frequency tracker module is further configured to modify the increment between successive frequencies dynamically based on real-time patient responses, thereby optimizing the flicker frequency sequence for individual patients.

3. The system as claimed in claim 1, wherein the light controller element emits light in a wavelength range between most prominent visual wavelength band of light ranging from 450 nanometers and 650 nanometers to optimize stimulation of human cone photoreceptors.

4. The system as claimed in claim 1 , wherein the communication module transmits the logged data using an encrypted wireless communication protocol selected from Bluetooth Low Energy (BLE) with proprietary security extensions or Wi-Fi Protected Access 3 (WPA3).

5. A method for screening of hepatic encephalopathy by visual perception ability, said method comprising: a. emitting flickering light to the subject at a starting frequency using a spectrally filtered and intensity-calibrated light source; b. incrementally adjusting the flicker frequency in discrete ascending or descending steps based on real-time subject feedback; c. resetting the light source to a non-flickering baseline between successive steps to achieve flicker fusion threshold faster;d. detecting subject responses indicating perception or non-perception of flicker at each frequency step; e. recording timestamps, corresponding flicker frequencies, and subject responses; and f. transmitting the recorded data securely to a remote computing device for analysis, wherein the increment between successive frequencies is dynamically adapted based on detected subject feedback to enhance measurement accuracy.

6. The method as claimed in claim 5, wherein the method further comprises dynamically adjusting the flicker frequency increment based on previous subject feedback to fine-tune the frequency sequence towards the critical flicker fusion frequency threshold.

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