Retina recognition technology captures and analyzes the patterns of blood vessels on the thin nerve on the back of the eyeball that processes light entering through the pupil.
Retinal patterns are highly distinctive traits. Every eye has its own totally unique pattern of blood vessels; even the eyes of identical twins are distinct. Although each pattern normally remains stable over a person's lifetime, it can be affected by serious physical injury or by certain diseases such as glaucoma, diabetes, high blood pressure, and autoimmune deficiency syndrome.
The fact that the retina is small, internal, and difficult to measure makes capturing its image more difficult than most biometric technologies. An individual must position the eye very close to the lens of the retina-scan device, gaze directly into the lens, and remain perfectly still while focusing on a revolving light while a small camera scans the retina through the pupil. Any movement can interfere with the process and can require restarting. Enrollment can easily take more than a minute. The generated template is only 96 bytes, one of the smallest of the biometric technologies.
One of the most accurate and most reliable of the biometric technologies, it is used for access control in government and military environments that require very high security, such as nuclear weapons and research sites. However, the great degree of effort and cooperation required of users has made it one of the least deployed of all the biometric technologies. Newer, faster, better retina recognition technologies are being developed.
While factors such as dust, grease, and perspiration that can make fingerprint techniques difficult do not affect retinal scanning, and injuries to the hand or fingers are more common than severe eye injuries.
- GAO, Information Security: Challenges in Using Biometrics 8-9 (GAO-03-1137T) (Sept. 9, 2003) (full-text).