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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 27 February, 2008 Next Week's Question
Retina, iris in human eye are more reliable for ID than fingerprint
Question
Is the human eye like a fingerprint? Can it be used for positive identification purposes?

Question
Even though you may have seen high-tech eye scanners in various science fiction films (Minority Report, James Bond films, etc), the reality is that they are, well, real. In fact, the eye, in many ways, is much better than a fingerprint for identifying people accurately.

There are 2 structures inside the eye which are currently used for identification, and, unlike a fingerprint which can change over time or be purposely altered, these structures remain fairly unchanged throughout a person's life. The first structure is called the retina which is the back layer of the eye and acts like the film in a camera and processes the light and images we see. The retina is made up of an intricate network of crossing blood vessels and it is this unique meshwork which is used by retinal scanners to accurately identify people.

The other ocular structure which is used in ID scanners is the iris, or round, colored part of the eye in front. The iris, and its central pupil, act similarly to the lens or aperture of a camera and monitors the amount of light that enters the eye. The human iris is composed of small crypts, pits, striations, fibers, furrows, pigment and other structures which create its unsurpassed uniqueness. The iris appearance is so complex and unique that not even your own right and left irises are the same! Even identical twins have different iris patterns.

Once an iris pattern is converted to mathematical code using a proprietary algorithm, the likelihood of 2 people having the same pattern is a staggering 1 in 10 to the 78th power (the odds of winning the lottery or getting struck by lightning are much much higher). Because of this, and the relative ease for cameras to recognize it, the iris will probably beat out the retina in future scanning technology. Eye scanners are currently in use at the CIA, FBI & NASA but there is a very real possibility that in the near future you may be getting money out of an ATM, not with your card but with your eye!

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