Amazon’s latest patented technology was described in patent no. US 9317113 (filed in 2012 at the USPTO) as “gaze assisted object recognition.”
The technology relies on cameras in your smart phone or glasses that determine the direction of your eye gaze and pinpoint the object (e.g. light switch or book) you want to influence an action upon (e.g. turn on/off or buy). Staring at that object for a set minimum amount of time with or without using a command would allow the user to complete actions without interacting directly with the object to execute the action.
More information on the patent can be found here: https://www.google.ch/patents/US9317113