Blindness, Geographic Atrophy, Retinal Dystrophies
Conditions
Brief summary
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.
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.
Interventions
DEVICEA 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.
Sponsors
University Medical Center Goettingen
EKFZ Else Kroener Fresenius Center for Optogenetic Therapies
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
NONE
Intervention model description
Participants are assigned to one of two groups (blind patients or healthy subjects). Each participant undergoes a single-session assessment in which multiple device conditions are tested within-subject. The study used a mixed-design with one between-subject factor (group: blind vs. healthy participants) and one within-subject factor (condition visual, auditory, combined). Phase A: proof of concept study (22 participants) Phase B: device optimization (11 blind participants of Phase A)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Fixation stability - change from baseline fixation stability recorded without acoustic fixation device compared to fixation stability recorded with acoustic fixation device | Day 1 | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in time to achieve fixation over repeated trials | Day 1 | 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. |
| Subjective exhaustion rating (Likert scale, 1-10) | Day 1 | 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. |
| Difference in fixation stability (BCEA, time to fixate in ms) between blind and healthy participants across feedback conditions | Day 1 | 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. |
| Correlation between pupil diameter change (mm) and fixation stability (BCEA) | Day 1 | 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). |
| Comparison of fixation stability with clinical and imaging parameters | Day 1 | 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. |
Countries
Germany
Contacts
PRINCIPAL_INVESTIGATORDorothea S Laurence, MD
University Medical Center Goettingen
Outcome results
None listed