In June 2017 Apple acquired SMI SensoMotoric Instruments GmbH for their advanced technology relating to eye tracking glasses and augmented reality. Below is a video from Siggraph 2015 showing off SMI's eye tracking glasses.  

The engineer behind those glasses was Walter Nistico who is now Apple's Engineering Manager – Deep Learning and Computer Vision. His LinkedIn profile states that he developed from concept to launch 3 products including the industry's first calibrationless Eye Tracking smart-glasses.

Today the US Patent & Trademark Office published the original patent application from SMI about these glasses that is now owned by Apple. At least some of the technology found in this patent has likely worked itself into Apple's upcoming mixed reality headset and eventually into Apple's smartglasses.

Apple's patent FIG. 1A below is a front view of a spectacle device; FIG. 1B a side view of the spectacle device of FIG. 1A; FIG. 1C a top view of the spectacle device of FIG. 1A; FIG. 10A a schematic side view of a spectacle device where the optical path of an eye camera extends in a straight line from the eye camera to an eye; and FIG. 10B a schematic side view of a spectacle device where the optical path of an eye camera extends from the eye camera via a mirror to the eye.

To dive into the deep details of this invention, review Apple's patent application number 20220061660. Over time, the seemingly bulky glasses will have been refined to appear more like those in our cover graphic.