Today, technologies that once lived only in the minds of science fiction writers are becoming commonplace in every area of our lives. For example, biometrics—or methods of measuring biological features for purposes of identification—are now widespread in all areas of our lives, whether we recognize them or not. Biometrics explain why it’s second-nature for many of us to activate our phones with a fingerprint scan or why certain devices only respond to the sound of our unique voices.

One of the most futuristic forms of biometrics involves iris or retinal scanning. You might be familiar with these technologies from movies or TV shows, but how does they work in the real world?

Retinal Scanning

The retina is a complex web of tissue and neurons that line the back of the eye, and it plays an essential role in vision by transmitting light into neural signals that our brains process as images. Retinas are so complex, in fact, that no two individuals—not even identical twins—share similar patterns. Combined with the fact that retinas do not change throughout our entire lives (with few exceptions), the uniqueness of retinas makes them a perfect biometric marker.

Retinal scans operate by shining a beam of low-energy infrared light into an individual’s eye as they look into a scanner. This beam of light “draws” a path onto the retina. During this process, the amount of light reflected will vary depending on the individual’s unique retinal pattern, and the scanner converts this pattern into a string of computer code and records it in a database. In the future, when individuals return to the retinal scanner, it will compare their retinas to records within its database to check for matches and thus positive identifications.

Iris Scanning

Whereas retinas are located at the back of the eye, the iris is a structure found at the front of the eye that regulates the size of the pupil, and they are perhaps best known as the small disc that gives the eyes their color. Iris scans use camera technology, along with a small level of infrared illumination, to develop images of the highly complex patterns inside the iris. These images are then digitally encoded and uploaded to databases so individuals can use their irises as a form of identification. One of the advantages of iris scanning is that it can be incredibly fast and enjoys incredibly low rates of false matches.