Motion-Acuity Test for Visual Field Acuity Measurement with Motion-Defined Shapes
February 23rd, 2024
A novel motion-based acuity test that allows the assessment of central and peripheral visual processing in low-vision and healthy individuals, along with goggles limiting peripheral vision compatible with MRI protocols, are described here. This method offers a comprehensive vision assessment for functional impairments and dysfunctions of the visual system.
We are searching for the potentially enhanced visual functions in patients with injured visual system. Our research suggests that peripheral vision with its sensitivity to motion may be able to partially compensate for the loss of the central vision. Optical tests are based on the measurements of the stationary shape features.
We are proposing to measure acuity, the sharp vision with shapes of an equal surface built from moving dots. For the first time, it is possible to measure acuity based on motion sensitivity. The proposed protocol offers an accessible tool to assess visual acuity by recruiting central and peripheral visual fields.
Also, the possibility to use positive or negative contrast to modify the velocity of dots and the coherence of direction is crucial for a more detailed description of the full visual field. An assessment of the interplay between central and peripheral parts of the visual field has a crucial role in understanding how lost functions might be taken over by the spare parts of the visual system and how this process can be supported by visual training rehabilitation procedures. To begin, prepare a quiet dimly lit room with a computer, keyboard, display, eye tracker, desk, chin rest, and chair.
Arrange the setup so the participants can sit with their chin on the chin rest, eyes aligned with the center of the upper half of the display and hands reaching the keyboard's arrow keys. Access the configuration text file and locate the line containing the text, patient_name=TestPatient. Replace TestPatient with the specific identifier of the subject being examined.
Then instruct the subject to sit in front of the display, ensuring that their chin is rested on the chin rest and their eyes are directly aligned with the center of the upper half of the display. Confirm the distance between the screen and the subject is accurate. Navigate to the Vizcacha2.
jar directory on the computer and initiate the program. Guide the participant to consistently focus on the fixation cross located at the center of the screen throughout the experiment. On each side of the screen, a circle or an ellipse will be displayed equidistant from the central fixation cross.
The participant's task is to select the circle over the ellipse using the left and right arrow keys. Once the participant is ready, press the S key to commence the experiment. Terminate the program after four reversals or the maximum number of trials has been reached.
To update the newly obtained threshold as the baseline for the subsequent stimuli presentations, use the Python script in the replacer folder and follow the onscreen instructions. To begin, arrange the setup for the motion acuity test and perform the test to determine its difficulty level. Then once the subject is prepared, open the configuration text file to proceed with the coherence test.
Comment out the line reading filename=Shape_Brt. txt at the beginning of the line. After that, uncomment the line below it which includes the Shape_dotsB_C.
txt task. Execute the Vizchacha2. jar program.
Simplify the task explanation for the subject. Once the participant is ready, press the S key to initiate the experiment. Afterwards, reopen the configuration text file.
Comment out the line filename=shape_dotsB_C. txt and uncomment the line that includes the shape_dotsW_C. txt task.
For the Direction Task, after opening the configuration text file, comment on the previously selected file name and uncomment the line that contains filename=shape_dotsB_D. txt task. Execute the Vizcacha2.
jar program. Explain the task to the participant and press the S key to begin the experiment. Then reopen the configuration text file.
Comment out the line filename=shape_dotsB_D. txt and uncomment the line below which includes the shape_dotsW_D. txt task.
For the velocity task, open the configuration text file and comment on the previously selected file name. Uncomment the line containing filename=shape_dotsB_V10_20. txt task.
Execute the Vizcacha2. jar program. Explain the task to the participant and press the S key to begin the experiment.
Then comment out the line shape_dotsB_V10_20. txt and uncomment the line below it, which includes the shape_dotsW_V10_20. txt task.
Overview
This study presents a novel motion-based acuity test designed to evaluate central and peripheral visual processing in both low-vision and healthy individuals. The method incorporates goggles that restrict peripheral vision and is compatible with MRI protocols, providing a comprehensive assessment of visual system functionality.
Key Study Components
Area of Science
- Vision Science
- Visual Processing
- Neurological Rehabilitation
Background
- Peripheral vision has been shown to potentially compensate for central vision loss.
- Traditional optical tests focus on stationary shape features, limiting insights into dynamic motion sensitivity.
- This study aims to fill that gap by assessing acuity through moving visual stimuli.
Purpose of Study
- To assess the interplay between central and peripheral vision in individuals with visual impairments.
- To determine how lost functions can be compensated through peripheral vision.
- To support visual training rehabilitation procedures based on the assessment results.
Methods Used
- A computer-based motion acuity test was developed and executed in a controlled environment.
- Participants were positioned using a chin rest for consistent eye alignment with the display.
- The test involved measuring acuity with moving dots, utilizing configuration files for various tasks.
- Comprehensive instructions were provided to enhance participant engagement and accuracy.
Main Results
- The study illustrates the capacity of motion sensitivity to improve acuity assessment in low-vision cases.
- Participants engaged in tasks that required distinguishing between shapes, ultimately providing insights into their visual field capabilities.
- Key findings suggest that proper assessment can lead to effective rehabilitation strategies leveraging intact visual functions.
Conclusions
- This research demonstrates a promising method for evaluating visual processing deficits and enhancements.
- The findings bolster understanding of compensatory mechanisms within the visual system.
- Implications extend to clinical applications in visual rehabilitation and training for affected individuals.
