AMA Manual of Style - Stacy L. Christiansen, Cheryl Iverson 2020
Clock Referents
Correct and Preferred Usage
Occasionally, reference to a locus of insertion, position, or attitude is given in terms of a clock-face orientation, as seen by the viewer (see 18.1.4, Numbers and Percentages, Use of Numerals, Measures of Time).
Ambiguous: |
The foreign body was observed in the patient’s left eye at 9 o’clock. |
Use: |
The foreign body was observed in the patient’s left eye at the 9-o’clock position. |
Note: The terms clockwise and counterclockwise can also be confusing. The point of reference (eg, that of observer vs subject) should be specified if the usage is ambiguous.