The formula to convert diopter to Snellen acuity is:
\[ \text{Snellen Acuity} = \frac{1}{\text{D} \times 0.25 + 1} \]
Where:
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.
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 1:
Using the formula:
\[ \text{Snellen Acuity} = \frac{1}{2 \times 0.25 + 1} = 0.444444 \]
Example 2:
Using the formula:
\[ \text{Snellen Acuity} = \frac{1}{3 \times 0.25 + 1} = 0.307692 \]
