As their fingerprints (their name correct) is unique, the possibility that two people have identical footprints is practically zero, and the eyes were visible features unique to each person, and they are beginning to be increasingly used to identify safe and made as easy.
There are two components of the eye presenting these features, namely the iris and retina, and we'll talk below about both.
The iris has two visible features: color and those stripes radiating outward from the pupil, like spokes of a wheel. Eye color is used for a long time, but only as a relative method of identification, accompanied by other features, all relative (height, hair color, weight, etc.).
For a precise identification using increasingly more second feature, namely streaks mentioned above. These striped pattern that is formed is unique to each person and kept unchanged for a very long time, so it can be safely used for a quick and accurate identification.
Appeared so in the last 15-20 years, iris scans appliances, using most often infrared light for better clarity and compare the results with a database, some of these devices with extremely low error rate.
Of course, as with any relatively new technology, iris scanning is still not perfect and there are still some shortcomings related to both the technology itself and some biological aspects (eg, alcohol may modify footprint iris), but many drawbacks certainly they will be eliminated in the future. This sense of identity began to be used at the border, police in some private companies (like Google) or as an alternative name and password for accessing secure sites.
This presents a complex network of blood vessels that is visible and forming very complex patterns, unique to each individual. As in the case of fingerprints or the iris pattern, the possibility that two persons have identical retinal vascular pattern is extremely low. Also, in most cases this pattern remains unchanged throughout life and can be altered only if a person suffers from diabetes, glaucoma or retinal degenerative diseases. It is considered that retinal scan identification method is exceeded only as accurate DNA analysis, with an estimated error rate of one in a million. In order to identify the analysis was created retinal camera that scans the retina. It uses infrared light projected by the retina and blood vessels present there absorb this light to a greater extent than the surrounding tissue, helping it stand out. This method of identification used the FBI, CIA and NASA and in some prisons or banks. Retinal scan is also used for medical purposes, as discussed in more detail in the preceding article.
As with the analysis of the iris, retinal scan may be hindered by the existence of problems (cataracts or astigmatism pronunciation), but technological advances will remove surely these shortcomings, especially as the advantages of such identification methods are very high (speed, security increased , accuracy).