Scientists have created a robotic lens that is controlled by small eye movements, including double blinks to zoom in and out. 

Most soft robots are controlled manually or pre-programmed but the lenses mimic the natural electric signals in the human eyeball that are active even when the eye itself is closed.

Researchers from the University of California San Diego harnessed this natural charge to control the lens.

They measured the electrical potential of the eye – called the "electro-oculographic signal" – and then made lenses that would respond to that activity. 

Lead researcher Shengqiang Cai from the university told New Scientist: "Even if your eye cannot see anything, many people can still move their eyeball and generate this electro-oculographic signal."

The lens is made from polymers that expand when electric current is applied.

It is controlled using five electrodes surrounding the eye which act like muscles. When the polymer becomes more convex the lens effectively zooms in.