Retinography: What is it? How does it work? Applications, Advantages and Disadvantages

It is a sophisticated means of identifying people by the pattern of blood vessels in the retina (the innermost layer of the back of the eye).

The field of medicine has advanced in recent decades exponentially and all, thanks to the technological advances that have been taking place within the scientific community.

Whose expertise has made possible hundreds of devices that are less invasive and more efficient for the diagnosis of this or that condition? Such is the case with retinography.

Retinography requires using a special scanner the size of a shoebox to map the unique pattern of blood vessels in the retina.

The pattern is so complex that even identical twins do not have the same configuration of blood vessels. Those who favor its use claim that retinography has an error rate of only one in a million.

Currently, there are several biometric devices in use, machines that can identify people by their physical characteristics.

Some examples include fingerprint scanners and devices that can recognize a particular voice, hand, or signature. The retinal scanner is another addition to the identification toolkit.


How the retinal scan works

A retina scanner uses infrared light for mapping. When a person looks inside the eyepiece, an invisible beam of low-energy infrared light traces a circular path in the retina at the back of the eye.

The blood-filled capillaries absorb more infrared light than the surrounding tissue. Because of this, there is a variation in the intensity of the reflection.

The scanner measures this reflection at 320 points along the beam’s path. Next, assign an intensity degree between zero and 4,095. The resulting numbers are compressed into a computer code of 80 bytes. This code can be compared with patterns that have already been entered into the computer database.


Retinal scanners are already in use in the Pentagon and in government and corporate organizations where people need to be identified before entering an area.

New concerns about the security of terrorism and bank and credit card fraud have caused many organizations to think seriously about using retina scanners or other biometric means to identify people at airports and ATMs.

Some states require truck and bus drivers to be mapped by retinography. This information is used by state agencies to prevent impaired drivers from having licenses in several states to hide their driving records.

A proposed and more controversial use of retinal scanners is to develop a record of workers, where all are scanned to make sure they are legal citizens of the United States and, therefore, eligible for employment.

Critics of this proposal are concerned about possible invasions of privacy and violations of other personal rights.

Advantages and disadvantages

Retinal scanners have several advantages over fingerprints and speech recognition systems. They do not require as much computer memory as a fingerprint scan and are not subject to contamination by dirt or improper finger placement.

Unlike voice recognition systems, the retina scanner is not distracted by background noise or voice changes caused by the disease.

The main disadvantage of the retinal scanner is that the person has to focus on the scanner about three inches away. This restriction makes the device difficult the use the ATM because a person who uses an ATM rarely focuses on a very long area and is never close enough.

A new device called an iris scanner might be more beneficial for these everyday transactions since the scanning camera may be farther away and only has to scan the iris pattern (color portion) of the eye. This procedure does not require focusing on the camera.