What Do "OD" and "OS" Mean on an Eye Prescription?

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"OD" stands for the Latin term "ocular dexter" and means right eye, while "OS" stands for "ocular sinister" and means left eye, according to All About Vision. These terms are traditionally used on eyeglass and contact lens prescriptions though many eye doctors have begun to modernize this practice, opting for "RE" and "LE" to signify right eye and left eye.