| abstract |
A computer-readable medium includes computer-executable instructions that cause a processing unit of a user device to instruct a user to stand a predetermined distance from the user device, acquire an image of the user, and determine a user interpupillary distance based on the acquired image. The user interpupillary distance indicates a distance between the user's pupils in terms of pixels. The computer-executable instructions further cause the processing unit to determine a current distance between the user and the user device based on the user interpupillary distance, a predetermined interpupillary distance, a width of the acquired image in terms of pixels, and a field of view of the camera. Additionally, the computer-executable instructions cause the processing unit to display the current distance between the user and the user device on a display and display an eye chart when the determined current distance is equal to the predetermined distance. |