Developed in the 1980s, retinal scanning is one of the most well-known biometric technologies.

Once the scanner device captures a retinal image, specialized software compiles the unique features of the network of retinal blood vessels into a template.
Retinal scan is a highly dependable technology because it is highly accurate and difficult to spoof, in terms of identification.  The technology, however, has notable disadvantages including difficult image acquisition and limited user applications.  Often enrollment in a retinal scan biometric system is lengthy due to requirement of multiple image capture, which can cause user discomfort.  However, once user is acclimated to the process, an enrolled person can be identified with a retinal scan process in seconds.
Because retinal blood vessels are more absorbent of log-energy infrared light than the rest of the eye, the amount of reflection varies during the scan. The pattern of variations is converted to computer code and stored in a database.
Retinal scans should therefore not be confused with another ocular-based technology, iris recognition, which is described as the process of recognizing a person by analyzing the random pattern of the iris.The retina’s intricate network of blood vessels is a physiological characteristic that remains stable throughout the life of a person.As with fingerprints and iris patterns, genetic factors do not determine the exact pattern of blood vessels in the retina. This allows retinal scan technology to differentiate between identical twins and provide robust identification.