Abstract
Purpose :
The Argus II retinal prosthesis restores the ability to perceive impressions of light and movements in patients with end-stage photoreceptor degeneration. The system uses a processing unit to transform images from a camera into electronic data that are wirelessly transmitted to a retinal implant. A controlled trial was performed to compare the efficacy of a thermal camera to a visible-light camera.
Methods :
Four patients with an Argus II prothesis were selected at The Wilmer Eye Institute- 3 were male, the age range was 62-87, and all were Caucasian. Four tasks were performed: (1) Mobility: a human target stood at 3 or 5 meters (m) away. The participant was asked to walk to the target within 7 minutes while remaining in a 5 m boundary. (2) Bowls: up to 4 white bowls filled with hot water were placed on a black table. The subject was asked to indicate if a specific bowl was removed. (3) Cups: two white cups filled with hot water were placed at varying locations on a black table. The subject was asked to indicate which cup was closer. (4) Distant Person: a human target with a white shirt stood in front of the subject at 1, 3, or 6 m. The subject was asked to indicate the distance of the target. Varying numbers of trials, between 24-80, were completed for each task by each subject with each camera.
Chi-squared and Wilcoxon signed rank tests were used to assess how accuracy and response times vary between use of a thermal and standard camera. Accuracy was defined as successful task completion in the specified time and location (Task 1) or on first attempt (Tasks 2-4).
Results :
In each task, the thermal camera increased the subject’s accuracy as compared to the visible-light camera: 98.7% vs 57.5% (χ2=37.84, p<0.001) in the Mobility Task; 71.3% vs 52.1% (χ2=22.65, p<0.001) in the Bowls Task; 80.8% vs 63.9% (χ2=9.30, p=0.002) in the Cups Task; and 73.3% vs 34.2% (χ2=74.05, p<0.001) in the Distant Person Task. Wilcoxon signed-rank comparison of medians revealed no significant differences in response time between use of either camera in successfully completed tasks (p>0.05).
Conclusions :
In this study, the thermal camera outperformed the visible-light camera in all tasks. This suggests that a thermal camera may be of benefit in environments with distinct heat profiles. These findings have the potential to further improve the accessibility of hundreds of patients with the Argus II retinal prosthesis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.