Enter any 3 of the power of the first lens, seconds lens, distance between less, and the power of the crossed cylinder lens to determine the unknown variable.

## Crossed Cylinder Formula

The following formula is used to calculate the power of a crossed cylinder lens.

P = F1 + F2 + (F1 * F2 * d)

Variables:

- P is the power of the crossed cylinder lens (Diopters) F1 is the power of the first lens (Diopters) F2 is the power of the second lens (Diopters) d is the distance between the lenses (meters)

To calculate the power of a crossed cylinder lens, add the power of the first lens to the power of the second lens. Then, multiply the power of the first lens by the power of the second lens and the distance between the lenses. Add this result to the sum of the powers of the two lenses.

## What is a Crossed Cylinder?

A crossed cylinder is a type of lens used in optometry that has curvature in two orientations that are perpendicular to each other. One surface of the lens is shaped like a convex or concave cylinder, while the other is shaped like a cylinder that is rotated 90 degrees from the first. This allows the lens to correct for both astigmatism and other refractive errors like myopia or hyperopia at the same time.

## How to Calculate Crossed Cylinder?

The following steps outline how to calculate the power of a Crossed Cylinder lens.

- First, determine the power of the first lens (F1) in Diopters.
- Next, determine the power of the second lens (F2) in Diopters.
- Next, determine the distance between the lenses (d) in meters.
- Use the formula P = F1 + F2 + (F1 * F2 * d) to calculate the power of the crossed cylinder lens.
- After inserting the values of F1, F2, and d into the formula, calculate the result.

**Example Problem:**

Use the following variables as an example problem to test your knowledge.

F1 (power of the first lens) = -2 Diopters

F2 (power of the second lens) = 3 Diopters

d (distance between the lenses) = 0.5 meters