Biometric eye scan. Computer artwork of a human eye and printed circuit boards. Biometrics is the identification of individuals by their body parts. The iris, the coloured part of the eye, and the retina, the black part of the eye, have unique features in every individual. If an image of a person's eye is held on computer they can be identified by an eye scan. Other parts of the body used for biometric scanning include fingerprints and the contours of the face.