How to Use PD Ruler | ABBE Glasses - Free Printable

Problem Description:

The image shows a PD Ruler (Pupillary Distance Ruler), which is commonly used in optometry to measure the distance between the pupils of a person's eyes. The ruler has markings on both sides, and the task is likely to determine the pupillary distance (PD) based on the measurements indicated by the circled areas.

Observations from the Image:

1. The ruler has two sets of markings: one on the top and one on the bottom.
2. The top set of markings is labeled with "R" (right eye) and "L" (left eye).
3. The bottom set of markings provides numerical values for measurement.
4. Two specific points are circled:
- One near the "R" marking on the top.
- One near the "L" marking on the top.
5. The numerical values corresponding to these points are:
- The point near "R" is at approximately 60 on the bottom scale.
- The point near "L" is at approximately 94 on the bottom scale.

Solution Approach:

The pupillary distance (PD) is the distance between the centers of the pupils of the eyes. To calculate this:
1. Identify the numerical values corresponding to the right eye (R) and the left eye (L).
2. Subtract the smaller value from the larger value to get the PD.

From the image:
- The value for the right eye (R) is 60.
- The value for the left eye (L) is 94.

Calculation:

\[
\text{PD} = \text{Value at L} - \text{Value at R} = 94 - 60 = 34
\]

Final Answer:

\[
\boxed{34}
\]

Explanation:

The pupillary distance (PD) is the horizontal distance between the centers of the pupils of the eyes. In this case, the PD is calculated as the difference between the numerical values corresponding to the right and left eye markings on the PD ruler. The result, 34, indicates that the distance between the pupils is 34 mm. This measurement is crucial for fitting eyeglasses or contact lenses properly.