The Difference between the Iris and the Retina and Why It’s Important In Biometric Identification

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Iris recognition and retinal scanning are both very reliable modalities for biometric identification. However, both possess different characteristics that have a strong impact on their performance based on the environment and deployment purpose. Both biometric modalities use contactless scanners, but there are notable differences between iris recognition and retinal scanning; one being that iris recognition is considered non-invasive, and retinal scanning as invasive because it beams visible light into the eyes during the scanning process.

These biometric identification technologies are often misunderstood and incorrectly assumed to be one in the same despite their distinct differences. In this post, we will discuss the differences between iris recognition and retinal scanning.

Retinal Scanning

The human retina is a thin tissue composed of neural cells situated in the posterior portion of the eye. Because of the complex arrangement of the capillaries that supply the retina with blood, each person’s retina is unique. The network of blood vessels in the retina is so complex that even identical twins do not share a similar pattern. Although retinal patterns may be altered in case of diseases such as diabetes, glaucoma or retinal degenerative disorders, the retina typically remains unchanged from birth until death. (Via Wikipedia –

Retinal scanning is used to map the unique patterns of a person’s retina. The blood vessels within the retina absorb light more readily than the surrounding tissue and are easily identified with suitable lighting. A retinal scan is performed by projecting an unperceived beam of low-energy infrared light into a person’s eye as they look through the scanner’s eyepiece. This beam of light traces a standardized path on the retina. Because retinal blood vessels are more absorbent of this light than the rest of the eye, the amount of reflection varies during the scan. The variation pattern is converted to a computer code and is stored in a database. Retinal scanning also has medical applications. Communicable illnesses such as AIDS, syphilis, malaria, chicken pox as well as hereditary diseases like leukemia, lymphoma, and sickle cell anemia impact the eyes. Pregnancy also affects the eyes. Similarly, indications of chronic health conditions such as congestive heart failure, atherosclerosis, and cholesterol issues first appear in the eyes.



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Retinal scanning biometrics are mostly utilized by high security government agencies like the FBI, CIA and NASA. One reason why retinal biometrics has not been widely adapted in the commercial scene is the expense of hardware devices.

Iris Recognition

The human iris is a thin, circular structure in the eye, responsible for controlling the size and the diameter of the pupils and thus the amount of light reaching the retina. “Eye color” is the color of the iris, which can vary for person to person. In some cases iris color can be hazel (a combination of light brown, green and gold), grey, violet, or even pink. In response to the amount of light entering the eye, muscles attached to the iris expand or contract the aperture at the center of the iris, known as the pupil. The larger the pupil, the more light can enter.

Iris recognition is an automated method of biometric identification that uses mathematical pattern-recognition techniques on video images of the irises of an individual’s eyes, whose complex random patterns are unique and can be seen from some distance.

Unprecedented Usability and Iris Image Quality in a Compact DesignUnlike retinal scanning, iris recognition uses camera technology with subtle infrared illumination to acquire images of the detail-rich, intricate structures of the iris. Digital templates encoded from these patterns by mathematical and statistical algorithms allow unambiguous positive identification of an individual. Databases of enrolled templates are searched by matcher engines at speeds measured in the millions of templates per second per (single-core) CPU, and with infinitesimally small False Match rates. Hundreds of millions of persons in countries around the world have been enrolled in iris recognition systems, for security and convenience purposes such as border control, and some national ID systems based on this technology are being deployed. Besides its speed of matching and its extreme resistance to False Matches, a key advantage of iris recognition is the stability of the iris as an internal, protected, yet externally visible organ of the eye.


The use of iris recognition biometrics for patient identification in healthcare has skyrocketed in addition to deployments for immigration and border control, time and attendance, and access control. Due to the combination of reliability, accuracy, speed and relative low costs (plus the fact that the technology is contactless and non-invasive), iris recognition is gaining popularity as the modality of choice for individual identification in a wide range of industries. Another advantage of iris recognition biometrics is its durability. A research study by The National Institute of Standards and Technology (NIST) suggests that the iris is a stable internal organ and iris recognition is usable for decades after initial enrollment.


In summary, let’s examine the differences between iris recognition and retina scanning:

  • Retinal scanning accuracy can be affected by disease; the fine texture of the iris remains remarkably stable.
  • Iris recognition is like taking a normal photograph of a person and can be performed from a distance; whereas retinal scanning requires the eye to be brought very close to an eyepiece.
  • Iris recognition is more widely accepted as a commercial biometric modality than retinal scanning.
  • While both are contactless, retinal scanning is considered to be invasive because it beams visible light into the eye whereas iris recognition uses a digital photograph for identification and is non-invasive.

The ability to differentiate between retinal scanning and iris recognition is essential if you are considering investing in biometrics and expect a high return on investment (ROI). We hope that we could clearly point out the differences between the two modalities through this informative post. If you need additional clarification, do not hesitate to drop us a line at:

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John Trader

John Trader is the Public Relations and Marketing Manager with M2SYS Technology, a recognized industry leader in biometric identity management technology. Headquartered in Atlanta, GA M2SYS Technology's mission is to pioneer the high-tech industry by delivering long-term value to customers, employees and partners through continued innovation and excellence in all aspects of our business. M2SYS continues to innovate, build and bring to market leading-edge biometrics solutions that revolutionize the industry and expand the applicability of biometrics technology in our marketplace. You can view their Web site at or contact them via e-mail at

One thought on “The Difference between the Iris and the Retina and Why It’s Important In Biometric Identification

  • January 5, 2023 at 4:10 am

    Iris recognition and retinal scanning are both reliable methods of biometric identification, but they have different characteristics that impact their performance based on the environment and purpose of deployment. Iris recognition uses a contactless scanner and is considered non-invasive, while retinal scanning uses a contactless scanner and is considered invasive due to the visible light beam used during the scanning process. Retinal scanning is used to map the unique patterns of a person’s retina, which remains unchanged from birth until death, and has medical applications as well.


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