Currency Features for Visually Impaired People

Acuity, visual - A measure of the sharpness of an individual's sight compared with that of a "normal" observer. Acuity is measured by finding the smallest letters a person can read at a distance of 20 feet, and expressing the result as the ratio of this distance to the distance at which a "normal" observer can read the same letters.

AMD - Age-related macular degeneration.

ATM - Automated teller machine.

Authenticate - To determine that a banknote is genuine currency.

Banknote - Paper currency.

BEP - Bureau of Engraving and Printing.

Blind - People are said to be blind if with their better eye they have at most light perception. People with this level of visual acuity are sometimes referred to as "functionally blind."

Blind, legally - People are said to be legally blind if the best corrected visual acuity in their better eye does not exceed 20/200, or if the maximum diameter of their visual field does not exceed 20 degrees. This definition is used primarily for official and legal purposes.

Cataract - A form of eye disease that affects vision. Cataracts are opacities within the crystalline lens. The crystalline lens is a structure in the eye between the cornea and the retina. It is an important optical element in the eye and must remain clear for high quality image formation. Cataracts reduce image quality, often resulting in low-contrast or blurry images. Cataracts are common in old age but are sometimes congenital or arise in conjunction with other eye diseases such as diabetic retinopathy.

Color - The perception in the eye-brain system produced by a nonwhite distribution of electromagnetic energy.

Contrast sensitivity - The ability to perceive small differences in shades of gray. One method for measuring contrast sensitivity is to reduce the contrast of dark letters on a white background until they can no longer be recognized. The lowest contrast at which the letters can be recognized is the threshold level, and the reciprocal of this is the contrast sensitivity.

Covert features - Features that are hidden in the banknote and are not intended to be made public. Used by the Federal Reserve for currency authentication and by law enforcement for forensic purposes.

Currency - Paper money in circulation.

Delaminate - To separate into constituent layers.

Denominate - To determine the value of a banknote.

Disability, visual - Blindness or low vision.

Embedded features - Features that are added during the paper-making process or inserted between laminated layers. They include threads, planchettes, fibers, microtaggants, microcapsules, and so on.

Enhanced fibers - Fibers that respond to ultraviolet, infrared, or other excitations to give identifiable reactions and are added to paper as a security feature.

Fibers - Dyed fibers embedded in the paper as a security feature. See also "Enhanced fibers."

Field, visual - The range of visual directions, centered on the line of sight, over which a standardized test target can be detected.

Fluorescence - The emission of light or other electromagnetic radiation of longer wavelengths by a substance as a result of the absorption of some other radiation of shorter wavelengths, provided the emission continues only as long as the stimulus producing it is maintained. In other words, fluorescence is the luminescence that persists for less than about 10-8 s after excitation.

Glare sensitivity - An adverse effect of bright lighting on vision. For example, oncoming headlights at night may adversely affect visibility of the road ahead in someone with glare sensitivity. Early cataracts may result in glare sensitivity.

Glaucoma - Glaucoma is a disease that occurs when the intra-ocular pressure becomes excessively high (due to inadequate drainage of aqueous humor from the anterior chamber of the eye). The excessive pressure can ultimately damage retinal cells, first resulting in loss of peripheral vision and later progressing (if untreated) to encompass the entire visual field.

Intaglio printing - A printing process where characters are formed as depressed areas on the printing plates. These are filled with ink, which is transferred to paper under pressure.

Issuing authority - An entity entitled to officially distribute banknotes.

Laminate - A sheet of material made of one or more bonded layers.

LED - Light-emitting diode.

Letterpress printing - Printing in which characters are formed by raised surfaces on the printing plates; a roller applies ink to these raised surfaces, and the plate is pressed against the paper to transfer the ink.

Light perception - People are said to have, at most, light perception if, with their better eye, they are able to detect the presence of light but are not able to determine the direction from which the light is coming.

Low vision - Best-corrected acuity less than 20/60 in the better eye. Sometimes defined as the inability to read regular newsprint with optimal reading glasses at normal reading distance.

Luminescence - See "Fluorescence" and "Phosphorescence."

Maculopathy - Disease associated with the central (macular) portion of the retina. Maculopathies usually have an adverse effect on high-acuity central vision. Age-related maculopathy is the most common form of low vision and afflicts many older people.

Microcapsules - Small particles, not visible to the eye that are added to substrate and that respond to ultraviolet, infrared, or other excitations to give identifiable reactions.

Overt feature - A feature that is made public and is visible or apparent without requiring special instruments. May require some instruction on how to observe it.

Paper - The substrate used in printing currency, usually based on cotton and linen fibers rather than on cellulose, as in ordinary paper.

Paper furnish - The fiber-water slurry from which the paper is made.

Peripheral field loss - Loss of vision outside of the central region of the visual field. In the extreme, it results in "tunnel vision," in which only a very narrow central region of vision remains.

Phosphorescence - The emission of light or other electromagnetic radiation that is delayed by more than 10-8 s following excitation.

Planchettes - Colored or reflective pieces of paper or plastic a few millimeters in diameter that are added during paper manufacture.

Recognize - To identify a piece of paper as a banknote, rather than as a similar sized piece of paper such as a store receipt.

Reprographic - Facsimile reproduction of graphic matter, for example, by photocopying or printing from a computer.

Retinopathy - A noninflammatory retinal disease.

Saturation, color - The degree of purity or chroma.

Security thread - The thread present inside the paper used in currency printing. It may carry the domination of the bill or may be fully metallized.

Substrate - The medium on which currency is printed. May be paper, plastic, or a laminated combination.

Smart Money - A form of currency that contains an encryption or information that can uniquely identify and verify the value of the currency.

Substrate - The medium on which banknotes are printed. May be paper, plastic, or a laminated combination.

Target - A form that an individual wishes to distinguish from its background. Specifically, the numerals on a banknote indicating the denomination.

Target population - A group that will be able to use a particular feature in banknotes.

Thread - See "Security thread."

Usher Syndrome - An inherited disorder characterized by moderate to profound hearing impairment, which is present at birth or shortly thereafter, and by progressive vision loss due to retinitis pigmentosa, a degeneration of the retina.

Visually impaired - A person with any form of visual disability that interferes with daily activities, including people who are blind or have low vision or people with peripheral field deficits, glare sensitivity, or losses in contrast sensitivity.

Watermark - A localized modification of the structure and opacity of a sheet of paper so that the pattern or design can be seen when the sheet is held to the light.