When I press the search button on my Lumia 930, there is no 'eye' symbol on the bottom of the Bing screen, only the three dots on the bottom right which have the 'settings' option.
You go into the camera app and choose the "Bing Vision" lens.
It appears that Bing Vision is gradually being withdrawn from Windows Phone. No one knows why, no one knows if those features will be included into Cortana at some point (opening her eyes as well as ears/mouth).
There's apps in the marketplace that covers some of the lost functionality, although it depends on what you want.