Research into eye recognition technology has occurred since 1935.  It was during that year an article appeared in the New York State Journal of Medicine that suggested that the pattern of blood vessels on the retina could be used to identify an individual (Computer Business Review, 1998).  Since 1935, extensive research and development has gone into establishing iris and retinal patterns and the uniqueness of them.

It has been well documented the uniqueness of eye identification.  The iris is so unique that no two irises are alike, even among identical twins, in the entire human population.  In actuality, identifying the iris and converting it to mathematical code, the probability that two irises will produce the same mathematical code is approximately one in ten to the 78th power.  The population of the earth is approximately ten to the tenth power (Iriscan, 1999).

The concept of a system that is able to identify an individual based on their iris was developed in America as well as Britain.  The key individuals in bringing this concept to reality were Leonard Flom and Aran Safir, two ophthalmologists.  The development of the actual iris scanning technology is credited to Dr. John Daugman.   Dr. John Daugman is the man responsible for the creation of the mathematical (algorithms) formulas used to measure the varying characteristics of one's iris.  These mathematical formulas were patented by Dr. John Daugman at Cambridge University in 1994 (The Economist, 1998).

In the iris alone, there are over 400 distinguishing characteristics, or Degrees of Freedom (DOF), that can be quantified and used to identify an individual (Daugman, J. & Williams, G. O. 1992).  Although, approximately 260 of those are used or captured in a "live" iris identification application.  These identifiable characteristics include: contraction furrows, striations, pits, collagenous fibers, filaments, crypts (darkened areas on the iris), serpentine vasculature, rings, and freckles.  Due to these unique characteristics, the iris has six times more distinct identifiable features than a fingerprint.

The iris is a robust method of identification since the iris remains unchanged throughout one's life and is not suspect to wear and injury.

Retinal scan identification is based on the blood vessel pattern(s) found on the back of the retina in one's eye.  The first retinal commercial product, EyeDentify 7.5, appeared in 1985 (Computer Business Review, 1998).

In identifying one's iris, there are two types of methods that are used by iris identification systems: passive and active. 

The active iris system requires the user to move back and forth so that the camera can adjust and focus in on the user's iris.   The active iris system method requires that a user be anywhere from six to 14 inches away from the camera.  The passive iris system is different in that it incorporates a series of cameras that locate and focus on the iris.  The passive iris system allows the user to be anywhere from one to three feet away from the camera(s).  This method provides for a much more user-friendly experience (International Biometric Group, 1999).

Actual iris identification can be broken down into four fundamental steps.  First, a person stands in front of the iris identification system, generally between one and three feet away, while a wide angle camera calculates the position of their eye.  A second camera zooms in on the eye and takes a black and white image.  After the iris system has one's iris in focus, it overlays a circular grid (zone's of analysis) on the image of the iris and identifies where areas of light and dark fall.  The purpose of overlaying the grid is so that the iris system can recognize a pattern within the iris and to generate 'points' within the pattern into an 'eyeprint'.   Finally, the captured image or 'eyeprint' is checked against a previously stored 'reference template' in the database.

The time it takes for a iris system to identify your iris is approximately two seconds.   A template iris pattern code contains between 256 and 512 bytes of data depending upon the manufacturer.  This small 'template' provides for instant identification and provides a definite advantage when it comes to database searches and archives.  As a result of this small "electronic footprint", up to 100,000 records a second can be scanned using a standard personal computer.  Furthermore, the mismatch rate is less than one in 100,000 (The Economist, 1998).

Retinal scans involve a low-intensity infrared light that is projected through to the back of the eye and onto the retina.  Infrared light is used due to the fact that the blood vessels on the retina absorb the infrared light faster than surrounding eye tissue(s).  The infrared light with the retinal pattern is reflected back to a video camera.  The video camera captures the retinal pattern and converts it into data that is 35 bytes in size (Industry Information: Biometrics, 1996).

Retinal scanning systems have predominately been implemented in high security access control situations.  The military as well as financial institutions make up most retinal scanning employments.  For instance, the Central Intelligence Agency (CIA), the Federal Bureau of Investigation (FBI), and the National Aeronautical Space Agency (NASA) have all been implementers of retinal scanning.  Other more recent customers have included the Cook County Prison in Illinois and defense contractor, General Dynamics.

Likewise, iris identification technology has been been predominately used in high-security access control situations.  Financial institutions have also explored the means of iris identification technology.  In fact, the English bank, Nationwide, just completed a test pilot of the world's first automated teller machine (ATM) machine equipped with iris identification capabilities.  Responses from customers were overwhelmingly favorable.  Citibank is also in the test pilot stages with iris identification technology.

Other high-profile applications include:

• Equine Research Institute in Utsunomiya, Japan, is using iris identification to identify racehorses.
• Iris scanners were used in the Winter Olympics in Nagano to identify biathlon participants before they were granted access to their rifles.

The current hurdle for retinal identification is that of user acceptance.  Retinal identification has several disadvantages including:

• susceptible to disease damage (i.e. cataracts)
• viewed as intrusive and not very user friendly
• high amount of both user and operator skill required
• not enough funding from government and private sectors

However, retinal identification continues to be one of the best biometric performers on the market with low false reject rates, a nearly zero percent false accept rate, small data template, and quick identify confirmations (Industry Information: Biometrics, 1996).

Iris identification is gradually gaining popularity and favorable press.  Experts predict that the "killer application" for iris identification technology will be e-commerce.  Engineers around the world are betting that legal tender in the e-commerce age will be digital certificate combined with a coded image of a person's iris (The Economist, 1998).

Prices need to come down before worldwide implementation occurs.

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