I take it you want to use eye movements for data input (rather than reading people's thoughts, which would be silly to consider). It's not the greatest idea, efficiency wise, but may have its strengths in terms of convenience. From a fairly [recent (2014) review of eye based HCI](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.708.7920&rep=rep1&type=pdf):

> It should be noted, though, that gaze control of [WIMP](https://en.wikipedia.org/wiki/WIMP_(computing)) is
noticeably slower and more error prone than control by conventional mouse
and keyboard (e.g. gaze typing reaches about 20 wpm which is far from the
80 wpm by a touch typist, see Majaranta et al. 2009a). 

And the 2009 paper they refer to for state of the art is ["Fast Gaze Typing with an Adjustable Dwell Time"](http://www.sis.uta.fi/~csolsp/docs/Majaranta_CHI_09.pdf). It's basically displaying a large virtual keyboard (like your phone/tablet does) and uses a specialized algorithm to reduce errors. I'm not familiar with the details of the latter, you'll want to read the paper for that.

Microsoft Research has a more [recent (2017) paper](https://www.microsoft.com/en-us/research/wp-content/uploads/2017/01/cascading_dwell.pdf) using a cascading virtual keyboard and it claims improvements for the average user. The latter paper also makes me wonder if the previous research overstated its results, because

> Participants were able to achieve
typing speeds of 12.39 WPM on average with our cascading
technique, whereas participants were able to achieve typing
speeds of 10.62 WPM on average with a static dwell time
approach.

I don't know what discrepancies are due to; methodology or what is being reported, I guess.

By the way, there's a [HCI stack exchange](https://ux.stackexchange.com/) where I'm sure there are more knowledgeable people on this.