Which abbreviation represents the administration of medication into the left eye?

The abbreviation that represents the administration of medication into the left eye is "OS," which stands for "oculus sinister" in Latin. This term is used specifically in the context of ophthalmology to denote the left eye. Understanding this abbreviation is crucial for accurately interpreting prescriptions and ensuring that medications are administered correctly, particularly in situations where eye drops or ointments are involved.

In clinical practice, "OD" stands for "oculus dexter," which indicates the right eye, while "OU" means "oculi uterque," referring to both eyes. "EN" does not relate specifically to the administration of medication to the eyes and is not a standard ophthalmic abbreviation. This makes "OS" the clear choice for indicating treatment targeted at the left eye.