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Symbols deciphered: The history of symbols and signs in medicine


The symbols, signs, and abbreviations used every day in medical records have ancient roots in history.



The symbols, signs, and abbreviations used every day in medical records have ancient roots in history.


Dr. Bohigian

Our Ophthalmic Heritage By George M. Bohigian, MD

In the everyday practice of medicine, physicians use symbols, signs, and abbreviations to record medical histories, physical examinations, diagnoses, and prescriptions. This article discusses the possible origins, evolution, and history of some of common notations and abbreviations. Written language is a form of progressive abstraction, which is constantly evolving.

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Signs and symbols

A patient’s name may be written in script, a practice which started in Mesopotamia or Egypt with hieroglyphic type of symbols. Hieroglyphic symbols were both pictorial as well as phonetic. We use the alphabet in written word. The alphabet is from the Greek Alpha and Beta.

The symbol of “Rx” connects back to ancient civilizations. The ancients believed that an evil heart travels to the eye and causes it also to be evil. The power of the eye that casts the evil spell and its ensuing evil was the result of a fateful glance. In today’s ophthalmological nomenclature, OD means oculus dexter or the right eye. OU can signify the plural form, oculi unitas (both eyes) or the singular form, oculus uterque (each eye). OS for ocular sinister indicates the left eye.

The belief that a “good eye” could counteract the evil eye may have been the cause of the ancient Egyptians’ creation of the myth of the Eye of Horus. The Eye of Horus thus became the hieroglyphic symbol of healing.


NEXT: Numbers, Decimals, and Zero


The symbol of the Eye of Horus indicated protection against evil and suggested completeness or good health. The left eye was the Wadjet eye or the sound eye of Horus; it signified the moon. The design of the Eye of Horus came to resemble the capital letter R and was a symbol for protection. Thus, physicians in ancient Rome in a prayer to Horus to heal the patient used the symbol Rx. The Rx was placed above medical formulas to enhance their effects.

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Numbers, decimals, and zero

These notations are found in ancient times. The numbers that we use today 1 through 10 are Hindu numerals; they originated in India with the Hindus who were also mathematical powers in the ancient world as were the Babylonians. This number system originated in India in the sixth or seventh century and introduced in Europe through the Arab mathematicians around the 12th century; hence, they are called Hindu-Arabic numerals. The shape of the numbers are traced from perhaps 1 being the symbol of the index finger, 2, 3 being shapes of the fingers and 5 probably from Hindu mantra “Hum” symbol. The decimal is from Hindu mathematicians.

The use of time and date

In communication, clinicians measure and record time and date. Measurement of time is based on the natural order of celestial observations of the sky. The calendars are generally based on a lunar or solar calendar. There are at least 40 different calendars currently used throughout the world-for example, the Jewish calendar, Chinese calendar, Islamic calendar, and Mayan calendar, as well as the current Gregorian calendar. The calendar has been changed at least 100 times since the birth of Christ.

The seven days of the week came from the concept of five planets the ancients could observe with their naked eye, plus the sun and the moon. Some of the names of the week are derived from these celestial objects, e.g., Saturday from Saturn, Sunday from the sun, Monday from the moon.


NEXT: Equal, Plus, and Minus Signs


The system of 24 hours comes from the Egyptian culture. The Egyptians divided the period from sunrise to sunset into 10 parts and added an hour before sunrise and an hour after sunset for a total of 24 hours in a day/night period. Sixty minutes in an hour is based on the Babylonian system, which was based on the number 60. Our culture is based on 10 or the decimal system probably due to ten fingers. They decided to take 60 units as the radius or 120 as the diameter of their standard circle. The circle using the old value three for Pi × 120˚ = 360 units. Hence they divided each degree into 60 units (our minutes) and each minute into 60 units (our seconds). The modern divisions of the earth are directly traceable to this, hence 360° in a circle.

Equal, plus, and minus signs

The equal sign was originally written out in long hand until 1543 when Robert Recorde, a textbook writer in England, tried to promote the symbol of a pair of parallel lines that is now used for the equal sign.

Plus, minus, and equal are all signs from antiquity. We use the ancient symbols of hieroglyphics for addition since it shows someone walking toward (added to) and the other hieroglyphics for someone walking away (subtraction). Recorde promoted the new style plus sign, which did have some popularity in Europe. William Oughtred introduced the “×” for simple multiplication in 1631 in England.


NEXT: The Staff of Asclepius


The staff of Asclepius

The ancients looked upon the snake as a symbol of health and healing because it could shed and regenerate its skin. Also snakes live in the earth in crevices of the earth and came closely associated with the underworld or realm of the dead.

The Staff of Asclepius is the proper symbol of medicine and is used today as the symbol of the American Medical Association. It consists of a wooden staff that represents plants or growth. The caduceus-which is incorrectly used as a symbol of medicine-is a staff of olive wood with a pair of wings topped with a pinecone and a pair of snakes coiled around the staff.



George M. Bohigian, MD, is professor of clinical ophthalmology, Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO.

Norman B. Medow, FACS, editor of the Our Ophthalmic Heritage, reviewed this column. He is director, pediatric ophthalmology and strabismus, Montefiore Hospital Medical Center, and professor of ophthalmology and pediatrics, Albert Einstein College of Medicine, Bronx, NY. He did not indicate a financial interest in the subject matter.


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