Which of the following prism conditions would likely not be noticed by the wearer?

When considering which prism condition might not be noticed by the wearer, it's important to examine the implications of each option.

The term "BU" refers to base up prism, which can help in vertical alignment of images. If the right eye (OD) has a base up condition and the left eye is not specified as having any base direction (indicated by the absence of a prism in the other eye), this means that any change in alignment due to base up prism in one eye may go unnoticed by the wearer. The brain often compensates for small discrepancies in visual inputs, especially if both eyes are not experiencing opposing misalignments or significant deviations; therefore, a slight base up prism in one eye may not create a noticeable effect.

In contrast, the other options, whether they indicate opposing prism conditions or include base in (BI) prisms, are more likely to create noticeable visual discrepancies for the wearer. Base in prisms would create convergence, leading to corresponding symptoms if there's a misalignment or imbalance that the visual system must reconcile. Additionally, if both eyes are specified with the same base direction (as in OU-BO), any added strain due to the prisms would typically be more apparent.

Thus, the presence of a base up