Diopter to Snellen Conversion Calculator

Convert Diopter to Snellen Acuity

Formula

The formula to convert diopter to Snellen acuity is:

\[ \text{Snellen Acuity} = \frac{1}{\text{D} \times 0.25 + 1} \]

Where:

What is Diopter?

A diopter is a unit of measurement for the optical power of a lens or curved mirror. It is the reciprocal of the focal length measured in meters. In the context of vision correction, it is used to describe the refractive power of eyeglasses or contact lenses needed to correct a person’s vision.

What is Snellen Acuity?

Snellen acuity is a measure of visual acuity, which is the clarity or sharpness of vision. It is typically represented by a fraction, such as 20/20, where the first number indicates the distance at which a person can clearly see a letter that the average person can see at the second number’s distance. The Snellen chart is commonly used to test and express visual acuity.

Example Calculations

Example 1:

Using the formula:

\[ \text{Snellen Acuity} = \frac{1}{2 \times 0.25 + 1} = 0.444444 \]

Example 2:

Using the formula:

\[ \text{Snellen Acuity} = \frac{1}{3 \times 0.25 + 1} = 0.307692 \]