Retinal Scanning

Definition

A retinal scan is a biometric technique that maps the unique patterns of a person’s retina using a low-intensity light source. Through a delicate sensor, a retinal scan examines the pattern of retina blood vessels, which remains unchanged from birth until death.

What is a retina?

The retina is the innermost layer of cells lining the back wall inside the eye. The retina contains multiple layers of sensory tissue and millions of photoreceptors. This layer of tissue detects light and creates electrical impulses that are sent through the optic nerve to the brain which enables a person to see. In other words, the retina fundamentally acts as the image sensor in a camera.

Made up of multiple layers of neurons, the neural retina is adjoined by a series of synapses, wherein an outer layer of pigmented epithelial cells support it. The main light-sensing cells in the retina are comprised of two specific types of photoreceptor cells: rods and cones. While rods generally function in dim lighting conditions and are responsible for black-and-white vision, cones are built for brighter lighting conditions and are in charge of recognizing colour. 

What is an iris?

The iris is the pigmented, annular muscular curtain near the front of the eye, which controls the size and diameter of the pupil. The iris regulates the amount of light that enters the eye by opening and closing the pupil, which is crucial in maintaining a proper line of vision.

The iris is the determining factor of a person’s eye color. Two distinct layers make up the iris: the stroma, which is the pigmented fibrovascular layer in the front, and pigmented epithelial cells which are below the stroma.

What is iris recognition?

Iris recognition technology is an automated method of biometric authentication that utilizes software algorithms and video camera technology with minimal infrared illumination that can analyze minute textures of the iris. Iris scanning is capable of capturing images of the intricate and unique structures of the iris even from a distance. Since every iris is unique to an individual, iris recognition makes for an ideal form of biometric verification.

How accurate are retinal scanning and iris recognition?

Retinal scanning and iris recognition are two of the most accurate and reliable biometric modalities used for identity verification and authentication. 

One study on biometric authentication discovered that the false rejection rate of retinal scanning technology stands at 1.8%. This comprehensive study has clearly established that retinal scanning is the most accurate among all other biometric modalities. 

Iris recognition is one of the fastest biometric modalities for identity verification and authentication on the market. Like retinal scanning, iris recognition also boasts one of the lowest rates of false acceptance and false rejection. As a matter of fact, the false rejection and false acceptance rate of iris recognition is significantly lower than that of fingerprints.

What is the difference between retinal scanning and iris recognition?

Both retinal and iris scanning are ocular-based biometric technologies. However, distinct differences exist which sets these two modalities apart that are suitable for specific use cases. 

While the texture of a person’s iris remains stable over time, the accuracy of retinal scan measurement can be affected by disease. Unlike the iris, the retina can be subjected to changes if an individual is afflicted with a disease or blindness. Close proximity to an eye scanner is also required in retinal scanning (much like looking into a microscope), whereas iris recognition, being a normal photo capture process, can be taken even from afar.

What are the pros and cons of retinal scanning?

The retina is regarded as one of the most reliable biometric modalities available in the marketplace nowadays. Since retinal recognition templates are incredibly small, it is quite fast to confirm the identity of a person. Once identity is verified through a retinal scan, there is almost no error given the high number of unique data points of the retina. Simply put, it is virtually impossible to be falsely accepted by a retinal recognition system.

However, there is a negative public perception regarding retinal scanning due to its intrusive nature. A lot of people assume that a retinal scan can pose a serious health risk to the eye (although unsubstantiated by scientific studies, it still persists). This is largely due to having to place the eye into a receptacle while a subtle infrared light is beamed directly onto it.  Therefore, retinal scans require a massive amount of cooperation from a user to capture high quality images. Retinal scans can therefore entail multiple attempts and quite a long time to get the best results in accurately verifying the user. 

Where is retinal scanning used?

Given the accuracy of its matching capabilities, retinal scan technology is difficult to spoof and is typically deployed in top-level security applications for authentication and identification.

With an estimated error rate of just one in ten million, retina recognition technology has been implemented by several US government agencies such as the Federal Bureau of Investigation (FBI), Central Intelligence Agency (CIA), and National Aeronautics and Space Administration (NASA). Nowadays, retinal scanning has also been deployed in a number of applications, including ATM identity verification and prevention of welfare fraud. 

What are the pros and cons of iris recognition?

Since iris patterns stay practically unchanged throughout a person’s lifetime, iris recognition is one of the most accurate biometric modalities that are commonly deployed. The false acceptance rate and false rejection rate of iris scanning is extremely low, guaranteeing a higher rate of accuracy in identity verification and authentication. 

Iris recognition is an easy-to-use technology, wherein a person only needs to stand still in front of the camera, and the rest is taken care of by the technology behind it. No direct physical contact is required between the person and the camera, making iris recognition completely non-intrusive.

Being one of the emerging biometric technologies, iris recognition comes at a relatively high cost. Iris scanners are quite expensive, making them mostly accessible to governments and large corporations. To initiate a reliable iris recognition process, a proper setup is a  must.  It might take more than a few attempts to get the capture process right as eye scanners can be sensitive to reflection. Moreover, they also require a person to stay still and avoid extra movements. 

Where is iris recognition used?

For reliable identity verification, digital templates based on the patterns of the irises of a person’s eyes can be used for comparison and matching. The speed of iris scanning and the visibility of the eye, alongside the incredibly low rate of false matches, are some of the main reasons why this biometric technology is gaining traction.

Iris recognition can be deployed in a wide variety of applications such as airport security, sensitive construction tasks, and military operations. Iris recognition can also provide a unique identity for citizens who do not own a passport or other identity cards, giving them access to governmental services.

How safe are eye (retina and iris) scanning technologies?

Eye scanners scan the unique patterns of an individual’s retina and/or iris to accurately and quickly verify their identity to access restricted areas, services, or information. Although concerns exist that infrared rays could have a negative impact on vision, most experts believe that retinal and iris scanners pose no health risk to users.

Even if a retinal scan itself poses no danger to the eye, users sometimes complain of discomfort from the technology during the enrollment process. This has to do with leaning in and keeping their eye close to the scanning device in order for a scan to be accurate. Although an infrared light is beamed directly into the eye, there is no scientific study that supports the assumption that the retinal scan damages the vision of the user. 

On the other hand, iris scans capture a grayscale photo of a person’s iris and are generally considered non-intrusive and more comfortable to complete. 

Retinal Scan vs Iris Recognition: Which is better?

Based upon the unique physiological characteristics of the eye for identity verification, both retinal scan and iris recognition offer their own list of advantages and disadvantages.

Iris recognition has gained more widespread commercial adoption between the two. The acceptance of retinal scans by the general public is extremely low due to its inconvenient and invasive nature. On the other hand, iris recognition is considered more user friendly as it uses contactless digital photography to precisely verify identity. 

Retinal recognition is almost exclusively deployed in applications where extremely high levels of security are a requirement. Retinal scanning technology is mostly deployed in military installations and bases, nuclear facilities, and high-caliber laboratories.

Given the complexity of retinal biometrics, it is hardly surprising that retinal scanning technology only enjoys a low commercial acceptance. However, iris recognition is widely accepted as a commercially-viable modality compared to retinal scanning. With the cost of adopting iris recognition technology expected to decrease, iris scanning technology is expected to dominate the global market for biometric identity verification and authentication

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