This add-on collects nothing and transmits nothing.

It makes no network requests of any kind. It stores two values on your own device using
the browser's extension storage: which colour vision deficiency type you selected, and the
correction strength. There is no account, no sync, no analytics and no telemetry.

On opticquiz.com only, and nowhere else, it reads one value your own browser already holds
(the result of a colour vision test you took on that site) so it can set the correction
strength for you instead of asking you to type it. That value never leaves your device.

Full source: https://github.com/zengineco/opticquiz.com/tree/main/browser-extension