A woman presents a pair of "Shutter Shade" sunglasses at the 24th China International Optic Fair held in Beijing, Sept 14, 2011. Over 770 exhibitors from 23 countries took part in the fair. [Photo/Xinhua]

A female employee presents specially designed sunglasses at the 24th China International Optic Fair held in Beijing, Sept 14, 2011. [Photo/Xinhua]

Children wearing sunglasses pose for photos at the 24th China International Optic Fair held in Beijing, Sept 14, 2011. [Photo/Xinhua]

A staff member shows visitors the latest optometric tools at the 24th China International Optic Fair held in Beijing, Sept 14, 2011. [Photo/Xinhua]