A new type of eyeglass lens that rapidly darkens when you want it to, is soon to become a reality, according to researchers at the Georgia Institute of Technology in the US.

There are considerable limitations to the transitional, or photochromic lenses currently on the market, which fail to darken inside cars or under baseball caps. Furthermore many brands let the harmful rays seep through.

It also takes time for them to clear up when the sun disappears, which poses inherent safety implications.

A small electrical charge adds the magic touch to the Georgia Tech research team’s new development, which switches from clear to dark and back again in seconds, enabling the capacity for fine color tuning.

Any color in the entire range of hues in which sunglasses are commercially available is possible, according to the researchers, who say their method could be easily applied for retail versions.

Their paper was published in the journal American Chemical Society Applied Materials & Interfaces.