New York City Police Photograph Irises of Suspects

  The technology uses high-resolution images to identify unique patterns in the iris, the colored part of the eye. It is considered less intrusive than retinal scanning, which looks at patterns in the blood vessels in the back of the eye and can reveal information about a person’s health, raising privacy concerns.

http://www.nytimes.com/2010/11/16/nyregion/16retinas.html?_r=1&ref=nyregion