A retinal scan is a

biometric Biometrics are body measurements and calculations related to human characteristics. Biometric authentication (or realistic authentication) is used in computer science as a form of identification and access control. It is also used to identify ...

technique that uses unique patterns on a person's

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

blood vessels. It is not to be confused with other ocular-based technologies:

iris recognition Iris recognition is an automated method of biometric identification that uses mathematical pattern-recognition techniques on video images of one or both of the irises of an individual's eyes, whose complex patterns are unique, stable, and can ...

, commonly called an "iris scan", and eye vein verification that uses scleral veins.

Introduction

The

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

retina is a thin tissue made up of

neural cells In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes t ...

that is located in the posterior portion of the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

. Because of the complex structure of the

capillaries A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...

that supply the retina with

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in th ...

, each person's retina is unique, making retinal scans an emerging authentication method. The network of

blood vessel Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from ...

s in the retina is not entirely genetically determined and thus even

identical twin Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two ...

s do not share a similar pattern. Although retinal patterns may be altered in cases of

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye re ...

or retinal degenerative disorders, the retina typically remains unchanged from birth until death. Due to its unique and unchanging nature, the retina appears to be the most precise and reliable biometric, aside from DNA. The National Center for State Courts estimate that retinal scanning has an error rate of one in ten million. A retinal scan is performed by casting an unperceived beam of low-energy

infrared light Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

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 Blood vessels are the structures of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away fro ...

absorb light more readily than the surrounding tissue, the amount of reflection varies during the scan. The pattern of variations is

digitized DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a digital (i.e. computer-r ...

and stored in a

database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases spa ...

History

The idea for retinal identification was first conceived by Carleton Simon and Isadore Goldstein and was published in the New York State Journal of Medicine in 1935. The idea was ahead of its time, but once

technology Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, scie ...

caught up, the concept for a retinal scanning device emerged in 1975. In 1976, Robert "Buzz" Hill formed a corporation named EyeDentify, Inc., and made a full-time effort to research and develop such a device. In 1978, specific means for a retinal scanner was patented, followed by a commercial model in 1981.

In popular culture

Because of the relative obscurity and "high tech" nature of retinal scans, they are frequently used as a device in fiction to suggest that an area has been particularly strongly secured against intrusion. Some notable examples include: *In the movie '' Star Trek II: The Wrath of Khan'' (1982), Admiral Kirk gains access to top secret computer files by use of a retinal scan. *In the science fiction novel ''

The Long Result ''The Long Result'' is a 1965 science fiction novel by British writer John Brunner. Plot summary In the future, the human race has developed interstellar travel and has encountered other sentient races, none of whom have developed interstell ...

'' by John Brunner (1965), a retinal scanner is used to access a Remote Control Centre at a spaceport. *In the movie ''

Batman Batman is a superhero appearing in American comic books published by DC Comics. The character was created by artist Bob Kane and writer Bill Finger, and debuted in the 27th issue of the comic book '' Detective Comics'' on March 30, 1939 ...

'' (1966), Batman describes to Robin how the tiny vessels in the retina are unique to the individual, and by utilizing the portable retina scan device in the Batmobile, they confirm the identity of the Penguin. *In the comic book film series ''

X-Men The X-Men are a superhero team appearing in American comic books published by Marvel Comics, first appearing in ''The X-Men'' #1 by artist/co-plotter Jack Kirby and writer/editor Stan Lee in 1963. Although initially cancelled in 1970 due to ...

'' Charles Xavier uses a retinal scanner to unlock Cerebro. This is bypassed by the shape-shifter Mystique assuming his form and William Stryker using an unknown mechanism. *In the ''

Half-Life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

'' video game series, the scientists of Black Mesa are frequently shown operating retinal scanners to access locked doors or hidden devices. *Characters in the films ''

GoldenEye ''GoldenEye'' is a 1995 spy film, the seventeenth in the List of James Bond films, ''James Bond'' series produced by Eon Productions, and the first to star Pierce Brosnan as the fictional Secret Intelligence Service, MI6 agent James Bond (lit ...

'' (1995), '' Mission: Impossible'' (1996), '' Barb Wire'' (1996), ''

Entrapment Entrapment is a practice in which a law enforcement agent or agent of the state induces a person to commit a "crime" that the person would have otherwise been unlikely or unwilling to commit.''Sloane'' (1990) 49 A Crim R 270. See also agent prov ...

'' (1999), '' Minority Report'' (2002) and '' Paycheck'' (2003) and '' Charlie's Angels (film)'' (2000) utilize or try to deceive retinal scanners. *In the ''

Splinter Cell ''Tom Clancy's Splinter Cell'' is a series of stealth action-adventure video games, the first of which was released in 2002, and their tie-in novels that were endorsed by Tom Clancy. The series follows Sam Fisher, a highly trained agent of a ...

'' video game series, retinal scanners are used to identify agents within Third Echelon and guards within military/business complexes. *In the 2012 film ''

The Avengers Avenger, Avengers, The Avenger, or The Avengers may refer to: Arts and entertainment In the Marvel Comics universe * Avengers (comics), a team of superheroes ** Avengers (Marvel Cinematic Universe), a central team of protagonist superheroes o ...

'', characters gain access to a quantity of very rare

iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of ...

by using two devices: one which apparently hooks onto a victim's eyeball, and another which receives signals from the first to holographically reconstruct the retina to fool the scanner. *In the 1993 film ''

Demolition Man (film) ''Demolition Man'' is a 1993 American science fiction action film directed by Marco Brambilla in his directorial debut. It stars Sylvester Stallone, Wesley Snipes, Sandra Bullock, and Nigel Hawthorne. Stallone is John Spartan, a risk-taking po ...

'', Simon Phoenix deceives a retinal scanner by taking the eyeball from a prison doctor.

Uses

Retinal scanners are typically used for authentication and identification purposes. Retinal scanning has been utilized by several government agencies including the FBI,

CIA The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...

, and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ...

, and has also been used in prisons. Retinal scanning also has medical application. Communicable illnesses such as AIDS, syphilis,

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or deat ...

chicken pox Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV). The disease results in a characteristic skin rash that forms small, itchy blisters, which eventually scab ...

and

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

as well as

hereditary disease A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

s like

leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enl ...

, and

sickle cell anemia Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red b ...

affect the eyes.

Pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...

also affects the eyes. Likewise, indications of chronic health conditions such as

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually ...

, and

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membr ...

issues first appear in the eyes. Retinal scanning is sometimes confused with

, which has been employed for a wider scope of applications.

Pros and cons

Advantages * Low occurrence of false positives * Extremely low (almost 0%) false negative rates * Highly reliable because no two people have the same retinal pattern * Speedy results: Identity of the subject is verified very quickly Disadvantages * Measurement accuracy can be affected by a disease such as

cataracts A cataract is a cloudy area in the lens of the eye that leads to a decrease in vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble w ...

* Measurement accuracy can also be affected by severe

astigmatism Astigmatism is a type of refractive error due to rotational asymmetry in the eye's refractive power. This results in distorted or blurred vision at any distance. Other symptoms can include eyestrain, headaches, and trouble driving at ni ...

* Scanning procedure is perceived by some as invasive * Subject being scanned must be very close to the camera optics * High equipment cost

References

{{DEFAULTSORT:Retinal Scan Biometrics