Which of the following keratometry readings is considered shorthand and thus omits the axis of the flatter meridian?

The choice indicating "OD 42.25 / 43.50 x 85" is a correct representation of shorthand for keratometry readings, which often simplifies the full notation by omitting the axis of the flatter meridian. In this shorthand format, the two values represent the readings of the steeper and flatter meridians, respectively, while the axis of the steeper meridian is explicitly stated. However, the axis of the flatter meridian is not included, which is characteristic of shorthand representation in keratometry.

Using shorthand allows for easier communication among eye care professionals, especially when the axis of the flatter meridian is either not critical for certain calculations or is already understood within the context of clinical practice. This format is also beneficial for avoiding unnecessary complexity in documentation and helps streamline the reporting of corneal curvature values.

In contrast, the other answer choices either retain the angle of the flatter meridian, which is not typical of shorthand notation, or they provide conflicting formats that do not conform to the standard shorthand practice. This distinct feature makes the choice representative of shorthand in keratometry.