Real-time Acoustic Biofeedback for Enhancing Fixation Stability: A Proof-of-concept Study to Improve Ophthalmic Imaging Diagnostic Quality

The goal of this Proof of Concept Feasibility Study is to improve the fixation stability in patients with fixation loss due to blindness or central vision loss using a patented acoustic real-time feedback device. The main questions it aims to answer are:

1. Fixation guidance - can real-time acoustic biofeedback improve the fixation in healthy patients as well as patients with fixation loss?
2. Optimization of fixation guidance - testing of different stimuli to optimize an acoustic training protocol.
3. Optimization of imaging acquisition - testing improvement of both imaging quality and acquisition time using the acoustic feedback tool.

For the proof-of-concept-study, patients are asked to fixate on a target point in a darkened room and keep up the fixation. We record patients eye movements with near-infrared-lighting and a camera. Fixation is tested in three conditions - visual target only, auditory feedback only, and visual target followed by auditory feedback. In between each set of trials, patients are asked to rate their subjective exhaustion on a Likert scale. At the end of each recording session, patients are handed a questionnaire for feedback on our proof-of-concept study and device settings.

An ethics-approved extension phase is planned to further optimize device parameters and assess performance in a clinical setting.

Study Overview

• Status: Enrolling by invitation
• Conditions: Geographic Atrophy; Retinal Dystrophies; Blindness
• Intervention / Treatment: Device: A device providing acoustic real-time biofeedback

Detailed Description

The goal of this Proof of Concept Feasibility Study is to improve the fixation stability in patients with fixation loss due to blindness or central vision loss using a patented acoustic real-time feedback device. The main questions it aims to answer are:

1. Fixation guidance - can real-time acoustic biofeedback improve the fixation in healthy patients as well as patients with fixation loss?
2. Optimization of fixation guidance - testing of different stimuli to optimize an acoustic training protocol.
3. Optimization of imaging acquisition - testing improvement of both imaging quality and acquisition time using the acoustic feedback tool.

Primary endpoints: Fixation stability (in BCEA and distance from target center), fixation duration, time to fixate. We test fixation in two angles: neutral position (0°) and at 15° eccentricity. We compare three conditions: visual target only, combined visual and auditory feedback, and auditory feedback only.

Secondary endpoints: adaptation and training effects over time, exhaustion measured in a Likert scale. We measure changes of pupil diameter in response to acoustic and visual stimuli. We also compare efficacy between healthy subjects and subjects with fixation loss and compare efficacy between the three conditions.

For the proof-of-concept part of our study, patients are asked to fixate on a target point in a darkened room and keep up fixation for 10 seconds. We record patients eye movements with near-infrared-lighting and a camera. There are three blocks for each condition (visual, auditory, combined), each block consists of 10 trials per eye and per angle. In between each set of trials, patients are asked to rate their subjective exhaustion on a Likert scale. At the end of each recording session, we ask patients for their subjective feedback on which condition was easiest to keep up fixation, whether auditory stimuli were sufficient and open-ended questions on potential improvements of the setup.

An ethics-approved extension phase is planned to further optimize device parameters and assess performance in a clinical setting. We validate the findings of our proof-of-concept study and optimize the device settings by adding the acoustic fixation device to our imaging devices. We will compare the results to answer the question whether the acoustic fixation device will lead to an improved imaging quality and acquisition time.

• Study Type: Interventional
• Enrollment (Estimated): 22
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Germany
  • Göttingen, Germany, 37075
    • EKFZ Else Kroener Fresenius Center for Optogenetic Therapies, University Medical Center Goettingen

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Healthy participants:

• minimum age of 18 years
• no neurological or ophthalmological disease
• ability to perceive auditory feedback
• normal vision
• consent to participate in study

Patients:

• minimum age of 18 years
• existing ophthalmological diagnosis of fixation deficite or loss
• ability to perceive auditory feedback
• consent to participate in study

Exclusion Criteria:

• lack of ability to consent to participate in study
• reduced cooperation during examination or recording
• inability to perceive auditory feedback
• age below 18 years
• patients with nystagmus or inability to move eyes
• opacity of cornea or other ocular structures preventing successful eye tracking
• inability to communicate

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Blind participants; Blind participants receive auditory feedback via our acoustic fixation device in three conditions to assess effects on fixation.	Device: A device providing acoustic real-time biofeedback; We use a camera and an eye tracking software, linked with our spatial-audio mapping tool. Participants receive real-time audio feedback on the location of their gaze. Negative feedback sounds are encoded to convey distance and direction of the deviation from the center. When the patients fixate on the target area, they receive a positive feedback sound.; Other Names: eyeFAST - eye Fixation by Acoustic Stabilization & Tracking
Experimental: Healthy participants; Healthy participants receive the same auditory feedback via our acoustic fixation device in three conditions to assess effects on fixation.	Device: A device providing acoustic real-time biofeedback; We use a camera and an eye tracking software, linked with our spatial-audio mapping tool. Participants receive real-time audio feedback on the location of their gaze. Negative feedback sounds are encoded to convey distance and direction of the deviation from the center. When the patients fixate on the target area, they receive a positive feedback sound.; Other Names: eyeFAST - eye Fixation by Acoustic Stabilization & Tracking

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fixation stability - change from baseline fixation stability recorded without acoustic fixation device compared to fixation stability recorded with acoustic fixation device	In Phase A, we analyse the fixation stability as the distance from the target center (Median [IQR]), duration of fixation and time to achieve stable fixation (latency). We also use posthoc video analysis to generate the BCEA as a measure of fixation stability in each condition and each angle (0 and 15 degrees).	Day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in time to achieve fixation over repeated trials	Time required to achieve fixation was assessed across repeated trials to evaluate potential training or adaptation effects. We calculate the time to achieve fixation in seconds across 10 trials per eye per condition per angle. We compare the time to fixate in milliseconds of the first half of trials to the second half of trials.	Day 1
Subjective exhaustion rating (Likert scale, 1-10)	We test the subjective exhaustion of each participant after each recording session. We provide a scale from 1-10 (1 being extremely exhausted, 10 being not exhausted at all) for participants to provide subjecte exhaustion feedback.	Day 1
Difference in fixation stability (BCEA, time to fixate in ms) between blind and healthy participants across feedback conditions	We compare the efficacy of auditory feedback on fixation stabilty between the healthy and the patient subject group. We also compare the efficacy of the three modalities (combined, auditory and visual) in between groups and within each arm to assess the effect of auditory feedback.	Day 1
Correlation between pupil diameter change (mm) and fixation stability (BCEA)	Further, we measure the pupil reaction as changes in pupil diameter (mm) over time (seconds) across different feedback conditions (visual, auditory, combined) and correlate those changes with the achieved fixation stability parameter (BCEA).	Day 1
Comparison of fixation stability with clinical and imaging parameters	We further analyse the correlation between achieved fixation stability and clinical parameters (such as visual acuity, age of disease onset, year of diagnosis, clinical and genetic diagnosis) and imaging parameters (presence of EZ in OCT-Scans, thickness of retinal layers, perfusion density, vascular density of deep, intermediate and superficial retinal vascular plexuses in OCTA), fundus autofluorescence, visual field parameters and ophthalmological examination results.	Day 1

Collaborators and Investigators

• Sponsor: University Medical Center Goettingen
• Collaborators: EKFZ Else Kroener Fresenius Center for Optogenetic Therapies
• Investigators: Principal Investigator: Dorothea S Laurence, MD, University Medical Center Goettingen

Study record dates

Study Major Dates

• Study Start (Actual): August 27, 2025
• Primary Completion (Estimated): April 15, 2026
• Study Completion (Estimated): May 15, 2026

Study Registration Dates

• First Submitted: March 24, 2026
• First Submitted That Met QC Criteria: April 7, 2026
• First Posted (Actual): April 14, 2026

Study Record Updates

• Last Update Posted (Actual): April 14, 2026
• Last Update Submitted That Met QC Criteria: April 7, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Eye Diseases; Vision Disorders; Sensation Disorders; Retinal Diseases; Retinal Degeneration; Macular Degeneration; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Geographic Atrophy; Retinal Dystrophies; Blindness
• Other Study ID Numbers: 17/5/25

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No