A patient brings you an old pair of glasses for prism measurement. With the lensometer, how much total prism is in the glasses?

To determine the total prism contained in the old pair of glasses using the lensometer, it is important to consider both the amount of prism in each lens individually and how these prisms interact when combined.

In this scenario, we have a measurement showing 3 prism diopters base up in the right eye. This indicates that the right lens has an upward deviation in the light passing through it. Additionally, there is a measurement of 9 prism diopters base out, which means that the light is deviating outward on the horizontal plane.

When these two measurements are evaluated for total effective prism, they can be added together because they are in different planes (vertical and horizontal). Though the base directions differ, the total influence of prisms can be assessed by considering how they affect the alignment of the visual axes. The correct interpretation involves recognizing the vertical deviation (upward) and the horizontal deviation (outward) separately while noting that the total consideration combines these effects for understanding the overall prism in the glasses.

Thus, the answer of 3 prism diopters base up for the right eye combined with 9 prism diopters base out leads us accurately to represent the prism adaptation needed for this patient's visual requirements. This assessment provides the necessary clinical information about the