A retinal scan is a biometric technique that uses the unique patterns on a person's retina blood vessels. It is not to be confused with another ocular-based technology, iris recognition, commonly called an "iris scanner."
The human retina is a thin tissue composed of neural cells that is located in the posterior portion of the eye. Because of the complex structure of the capillaries that supply the retina with blood, each person's retina is unique. The network of blood vessels in the retina is not entirely genetically determined and thus even identical twins do not share a similar pattern.
Although retinal patterns may be altered in cases of diabetes, glaucoma or retinal degenerative disorders, the retina typically remains unchanged from birth until death. Due to its unique and unchanging nature, the retina appears to be the most precise and reliable biometric, aside from DNA. The National Center for State Courts estimate that retinal scanning has an error rate of one in ten million.
A retinal scan is performed by casting an unperceived beam of low-energy infrared light into a person’s eye as they look through the scanner's eyepiece. This beam of light traces a standardized path on the retina. Because retinal blood vessels absorb light more readily than the surrounding tissue, the amount of reflection varies during the scan. The pattern of variations is digitized and stored in a database.
The idea for retinal identification was first conceived by Dr Carleton Simon and Dr Isadore Goldstein and was published in the New York State Journal of Medicine in 1935. The idea was ahead of its time, but once technology caught up, the concept for a retinal scanning device emerged in 1975. In 1976, Robert "Buzz" Hill formed a corporation named EyeDentify, Inc., and made a full-time effort to research and develop such a device. In 1978, specific means for a retinal scanner was patented, followed by a commercial model in 1981.
In popular culture
The relative obscurity and "high tech" nature of retinal scans means that they are a frequent device in fiction to suggest that an area has been particularly strongly secured against intrusion. Some notable examples include:
In the movie Star Trek II: The Wrath of Khan (1982), Admiral Kirk gains access to top secret computer files by use of a retinal scan.
In the movie Batman (1966), Batman describes to Robin how the tiny vessels in the retina are unique to the individual and utilizing the portable retina scan device in the Batmobile they could confirm the identity of the Penguin.
In the Half-Life series, the Scientists of Black Mesa are frequently shown operating Retinal Scanners to access locked doors or hidden devices. Characters in the films GoldenEye (1995), Mission: Impossible (1996), Barb Wire (1996), Entrapment (1999), Minority Report (2002) and Paycheck (2003) utilize or try to deceive retinal scanners.
In the Splinter Cell series, retinal scanners are used to identify agents within Third Echelon and guards within military/business complexes.
In the 2012 film The Avengers, characters gain access to a quantity of very rare iridium by using two devices: one which apparently hooks onto a victim's eyeball, and another which receives signals from the first to holographically reconstruct the retina to fool the scanner.
Retinal scanners are typically used for authentication and identification purposes. Retinal scanning has been utilized by several government agencies including the FBI, CIA, and NASA. However, in recent years, retinal scanning has become more commercially popular. Retinal scanning has been used in prisons, for ATM identity verification and the prevention of welfare fraud. Retinal scanning also has medical application. Communicable illnesses such as AIDS, syphilis, malaria, chicken pox and Lyme disease as well as hereditary diseases like leukemia, lymphoma, and sickle cell anemia affect the eyes. Pregnancy also affects the eyes. Likewise, indications of chronic health conditions such as congestive heart failure, atherosclerosis, and cholesterol issues first appear in the eyes.
Pros and cons
- Low occurrence of false positives
- Extremely low (almost 0%) false negative rates
- Highly reliable because no two people have the same retinal pattern
- Speedy results: Identity of the subject is verified very quickly
- Measurement accuracy can be affected by a disease such as cataracts
- Measurement accuracy can also be affected by severe astigmatism
- Scanning procedure is perceived by some as invasive
- Not very user friendly
- Subject being scanned must be close to the camera optics
- High equipment cost
- Retina and Iris Scans. Encyclopedia of Espionage, Intelligence, and Security. Copyright © 2004 by The Gale Group, Inc.
- Cofta, Piotr; Furnell, Steven (2008). "Use of Biometric Data". Understanding Public Perceptions: Trust and Engagement in ICT-mediated Services. International Engineering Consortium. p. 153. ISBN 9781931695954. Retrieved 29 September 2014.
The error rate for fingerprint identification can be as high as 1 in 500, whereas a retinal scan boasts an error rate of 1 in 10,000,000.
- Retinography: How Retinal Scanning Works. Retrieved on 2007-04-02.
- "Eye Prints," TIME Magazine, Dec. 16, 1935. Retrieved on 2008-04-10.
- "Why retina scanning works better for James Bond than it ever would for us".
- Iris/Retinal Identification. Archived April 26, 2007, at the Wayback Machine. Wcu.Edu. Retrieved on 2007-04-02.
- Ostaff, Courtney. "Retinal Scans Do More Than Let You In The Door." Retrieved on 2007-04-02.
- "Iris Recognition vs. Retina Scanning – What are the Differences?", M2SYS Blog on Biometric Technology.
- Roberts, Chris. "Biometrics" Retrieved on 2009-06-11.