New York, Jan 29 (IANS): Here's the next generation of eyeglasses that quickly go from clear to shaded and back again when you want them to.

Researchers from Georgia Institute of Technology have designed a new kind of lens that can switch within seconds from clear to darkly shaded and back again in response to a small electrical charge that a wearer could control.

The discovery will benefit pilots, security guards and others who need such control.

"We can also fine-tune the colour of the lenses to match the full range of hues used in commercial sunglasses. The method used to make the lenses could be easily scaled up for manufacturing," said Anna Osterholm in John Reynolds' group at Georgia Institute of Technology.

In the study, Osterholm and the team pointed out that most transitional lenses now on the market do not meet many users' needs.

When wearers are driving or wearing a baseball cap, for example, the lenses stay clear rather than switching to a darker shade even in broad daylight.

Also, the majority of available versions don't block out the harshest light, such as bright light reflected off snow.

"And the change from coloured to clear can take several minutes, which has safety implications for certain users including airline pilots," the authors noted.

The new discovery is reported in the journal ACS Applied Materials & Interfaces.