Two caveats here: though this works in web browsers, you can't yet scroll horizontally through Metro-style apps.

ENGADGET: Hands-on with Tobii REX, a peripheral that brings eye-tracking to any Windows 8 PC (video)

But she didn't care to scroll through the thousands of Twitter and Facebook comments on her writing style.

WSJ: When Mom Goes Viral: Marilyn Hagerty, 85, Is Talk of Social Media