Facebook recently responded to Congressional questioning with a 452-page document which turns out to have also covered the company's use of its two eye-tracking patents filed last year. According to the company, neither of those patents have been used yet, as both were associated with possible security features for its subsidiary Oculus. More directly, the Facebook's report states that one of the patents was part of the company's search for viable security options for the Oculus Rift VR platform. That likely means the social media giant had planned to use the eye tracking software detailed in the patents as a way to read a wearers eye and secure log-in.
The second patent, which gauges the emotional response of users was intended to "reduce consumer friction." There's been no report of exactly how that would be implemented or how a user's emotional state would be used to that end. However, it could feasibly be used to avoid overexposure to a certain type of emotionally harmful content or to adjust a content feed as needed to prevent the more damaging effects often associated with social media. Barring that, the company could have used it for Big Data analysis as well. For now, the company says it hasn't actually built any technology using the patents and doesn't have any plans to in the near future. Facebook elaborated on that to say that if it did utilize the eye-tracking patents it has on file, it would take into account the security and privacy of its users. The result would be comparable to how it manages movement software. Presumably, that means it would be stored in an anonymized form and kept under lock and key anywhere it exists in the company's system.
The company has faced scrutiny and implemented several policy changes in the days, weeks, and months following its widely publicized Cambridge Analytica scandal. As a result, there will undoubtedly be quite a lot of other information seeping out over the coming days. Given the general size of Facebook's response to the Congressional inquiries, that could easily turn into weeks. In the meantime, it at least doesn't appear as though Facebook ever actually did anything with its two eye-tracking patents.