Snellenasteikkoon
Snellenasteikkoon is a term that refers to the Snellen chart, a widely used tool for measuring visual acuity. It is named after Dutch ophthalmologist Herman Snellen, who developed it in the 1860s. The chart consists of rows of letters of decreasing size, printed in a standardized font. Individuals are typically asked to read the letters from a specific distance, usually 20 feet (6 meters).
Visual acuity is commonly expressed as a fraction, such as 20/20. The top number represents the distance
The Snellen chart is a fundamental part of routine eye examinations conducted by optometrists and ophthalmologists.
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