Lea Symbols Test optotypes on a blanket to be used to test the visual acuity of a young child

The LEA Vision Test System is a series of

pediatric Pediatrics (American English) also spelled paediatrics (British English), is the branch of medicine that involves the medical care of infants, children, adolescents, and young adults. In the United Kingdom, pediatrics covers many of their youth ...

vision tests designed specifically for children who do not know how to read the letters of the

alphabet An alphabet is a standard set of letter (alphabet), letters written to represent particular sounds in a spoken language. Specifically, letters largely correspond to phonemes as the smallest sound segments that can distinguish one word from a ...

that are typically used in

eye chart __NOTOC__ An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. Eye charts are often used by health care professionals, such as optometr ...

s. There are numerous variants of the LEA test which can be used to assess the visual capabilities of near vision and distance vision, as well as several other aspects of occupational health, such as contrast sensitivity,

visual field The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it i ...

color vision Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different frequencies independently of light intensity. Color perception is a part of the larger visual system and is mediated by a co ...

, visual adaptation,

motion perception Motion perception is the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs. Although this process appears straightforward to most observers, it has proven to be a difficul ...

, and ocular function and

accommodation (eye) Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus (optics), focus on an object as its distance varies. In this, distances vary for individuals from the far point—the maximum distan ...

History

The first version of the LEA test was developed in 1976 by Finnish pediatric

ophthalmologist Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...

Lea Hyvärinen, MD, PhD. Dr. Hyvärinen completed her thesis on

fluorescein angiography Fluorescein angiography (FA), fluorescent angiography (FAG), or fundus fluorescein angiography (FFA) is a technique for examining the circulation of the retina and choroid (parts of the fundus) using a fluorescent dye and a specialized camera. ...

and helped start the first clinical laboratory in that area while serving as a fellow at the

Wilmer Eye Institute The Wilmer Ophthalmological Institute, also referred to as the Wilmer Eye Institute, is a component of the Johns Hopkins University School of Medicine. Ophthalmologist William Holland Wilmer opened the Wilmer Eye Institute in 1925. Its home was com ...

Johns Hopkins Hospital Johns Hopkins Hospital (JHH) is the teaching hospital and biomedical research facility of Johns Hopkins School of Medicine in Baltimore, Maryland. Founded in 1889, Johns Hopkins Hospital and its school of medicine are considered to be the foundin ...

in 1967. During her time with the Wilmer Institute, she became interested in

vision rehabilitation Vision rehabilitation (often called vision rehab) is a term for a medical rehabilitation to improve vision or low vision. In other words, it is the process of restoring functional ability and improving quality of life and independence in an indiv ...

and assessment and has been working in that field since the 1970s, training rehabilitation teams, designing new visual assessment devices, and teaching. The first test within the LEA Vision Test System that Dr. Hyvarinen created was the classic LEA Symbols Test followed shortly by the LEA Numbers Test which was used in comparison studies within the field of

occupational medicine Occupational and Environmental Medicine (OEM), previously called industrial medicine, is a board certified medical specialty under the American Board of Preventative Medicine that specializes in the prevention and treatment of work-related ill ...

Accuracy

Among the array of visual assessment picture tests that exist, the LEA symbols tests are the only tests that have been

calibrated In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...

against the

standardized Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organiza ...

Landolt C The Landolt C, also known as a Landolt ring, Landolt broken ring, or Japanese vision test, is an optotype—a standardized symbol used for testing vision. It was developed by the Swiss-born ophthalmologist Edmund Landolt. The Landolt C consis ...

vision test symbol. The Landolt C is an optotype that is used throughout most of the world as the standardized symbol for measuring visual acuity. It is identical to the "C" that is used in the traditional

Snellen chart A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his profe ...

. In addition to this, the LEA symbols test has been experimentally verified to be both a valid and

reliable Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * Reliability (computer networking), a category used to des ...

measure of visual acuity. As is desirable of a good vision test, each of the four optotypes used in the symbols test has been proven to measure visual acuity similarly and blur equally as well, supporting the test's

internal consistency In statistics and research, internal consistency is typically a measure based on the correlations between different items on the same test (or the same subscale on a larger test). It measures whether several items that propose to measure the same g ...

. A study published in ''Acta Ophthalmologica Scandinavica'' in 2006 showed that the Lea Symbols 15-line folding distance chart is clinically useful in detecting deficiencies in

visual acuity Visual acuity (VA) commonly refers to the clarity of visual perception, vision, but technically rates an animal's ability to recognize small details with precision. Visual acuity depends on optical and neural factors. Optical factors of the eye ...

in preschool children. The study, which compared visual acuity diagnoses from Lea symbols tests to those obtained via

ophthalmological Ophthalmology (, ) is the branch of medicine that deals with the diagnosis, treatment, and surgery of eye diseases and disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a ...

examination, revealed that the Lea symbols chart provided an accurate and sufficient assessment in 95.9% of the 149 preschool-age children tested. This suggests that Lea tests can be used confidently as an alternative to more costly and time-consuming pediatric tests of visual acuity.

Importance

The unique design of the LEA tests and their special optotypes allow for pediatric low vision to be diagnosed in children at much younger ages than standard vision tests allow. This is especially important in young children who possess other

physical disabilities A physical disability is a limitation on a person's physical functioning, mobility, dexterity or stamina. Other physical disabilities include impairments which limit other facets of daily living, such as respiratory disorders, blindness, epilepsy ...

mental disabilities Developmental disability is a diverse group of chronic conditions, comprising mental or physical impairments that arise before adulthood. Developmental disabilities cause individuals living with them many difficulties in certain areas of life, espe ...

and are entitled to receive early

special education Special education (also known as special-needs education, aided education, alternative provision, exceptional student education, special ed., SDC, and SPED) is the practice of educating students in a way that accommodates their individual di ...

benefits. More than half of children who suffer from low vision also have other impairments or disabilities. Most of the LEA tests can also be used on children with significant brain damage and serve as one of the few methods that can accurately assess visual acuity in these situations.

Versions

The LEA Vision Test System currently contains over 40 different tests which target the assessment of many aspects of vision and communication deficiencies in both children and adults.

LEA Symbols Test

The oldest and most basic form of the LEA test is simply referred to as the "LEA Symbols Test". This test consists of four

optotype __NOTOC__ An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. Eye charts are often used by health care professionals, such as optometr ...

s (test symbols): the outlines of an

apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

, a

pentagon In geometry, a pentagon () is any five-sided polygon or 5-gon. The sum of the internal angles in a simple polygon, simple pentagon is 540°. A pentagon may be simple or list of self-intersecting polygons, self-intersecting. A self-intersecting ...

, a

square In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...

, and a

circle A circle is a shape consisting of all point (geometry), points in a plane (mathematics), plane that are at a given distance from a given point, the Centre (geometry), centre. The distance between any point of the circle and the centre is cal ...

. Because these four symbols can be named and easily identified as everyday, concrete objects ("apple", "house", "window", and "ring"), they can be recognized at an earlier age than abstract letters or numbers can be. This enables preschool children to be tested for

long before they become familiar with the letter and numbers used in other standard vision charts. The LEA Symbols Test is often used in the form of the

three-dimensional In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values (''coordinates'') are required to determine the position (geometry), position of a point (geometry), poi ...

(3-D) LEA Puzzle. This puzzle incorporates color along with the four standard optotypes to allow for measurement of visual acuity in children as young as fourteen months of age.

LEA Numbers Test

The "LEA Numbers Test" was the second of the LEA tests that was developed and can be used to test the visual acuity of older children and even adults. This test has a layout similar to a typical

, with lines of numbers decreasing in size towards the bottom of the page. Like the optotypes of the LEA Symbols Test, these numbers are also calibrated against the Landolt C and blur equally.

LEA Grating Acuity Test

This test allows for the assessment of

grating A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. Gratings usually consist of a single set of elongated elements, but can consist of two sets, in which case the second set is usually perpendicu ...

acuity, especially in children who possess severe or multiple visual deficiencies. The "LEA Gratings Test" has also been shown to be successful in vision testing of children with

brain damage Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...

and is the only test that can reveal their limited capacity for the processing of large numbers of

parallel Parallel may refer to: Mathematics * Parallel (geometry), two lines in the Euclidean plane which never intersect * Parallel (operator), mathematical operation named after the composition of electrical resistance in parallel circuits Science a ...

lines.

LEA Contrast Sensitivity Test

Visual information that is presented in low contrast settings is very important to the process of

visual communication Visual communication is the use of visual elements to convey ideas and information which include (but are not limited to) signs, typography, drawing, graphic design, illustration, industrial design, advertising, animation, and electronic resourc ...

. It is especially vital to assess a child's contrast sensitivity at a young age in order to determine the distance and accuracy with the child can distinguish facial features. A very popular test designed specifically for this reason is the "Hiding Heidi Low Contrast Face Pictures" test (which the LEA Vision Test System produces a version of.) This test uses a series of cards depicting cartoon faces of different contrast levels. The contrast sensitivity assessment obtained from this test is very important in educational settings because children with contrast deficiencies have extreme difficulty receiving visual cues from body language or facial expressions and often can't read the blackboard or projector.Hyvärinen, L. (n.d.). Contrast sensitivity. Retrieved from http://www.lea-test.fi/en/assessme/educearl/part1/contrast.html

References

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External links

Official website
Diagnostic ophthalmology Optotypes