What does "left eye" refer to in medication terminology?

In medication terminology, "left eye" is represented by the abbreviation "OS," which stands for "oculus sinister" in Latin. This term is commonly used by healthcare professionals when prescribing medications for ocular conditions, as it distinguishes the left eye from the right eye and both eyes.

The use of "OS" is vital in ensuring that the correct eye receives the prescribed treatment, thus preventing potential medication errors that could affect the patient's health and recovery. This clear distinction is especially important in scenarios such as prescribing eye drops or ointments, where accuracy in targeting the affected eye is crucial for effective treatment.

Other terms in the question serve specific purposes, such as "AD" meaning "right ear," "AS" meaning "left ear," and "AU" meaning "both ears." While these abbreviations follow similar conventions, they refer to different anatomical locations and are not suitable for denoting the left eye specifically. Therefore, "OS" is the correct term for "left eye" in the context of medication terminology.