optotyyppejä

Optotyyppejä, often translated as optotypes, are standardized charts or figures used to test visual acuity. These are the symbols that individuals look at during an eye examination to determine how clearly they can see at a given distance. The most common optotypes are letters of the alphabet, such as those found on the Snellen chart. However, other types exist, including numbers, Landolt C rings (broken rings with a gap), and E shapes.

The purpose of optotypes is to provide a consistent and reproducible method for measuring visual sharpness. They are designed with specific proportions and sizes, so that as the optotypes get smaller, the visual acuity is reduced. The distance at which a person can correctly identify a specific line of optotypes is then used to calculate their visual acuity score. For example, a visual acuity of 20/20 means the individual can see at 20 feet what a person with normal vision can see at 20 feet. Different optotypes are employed for different age groups and abilities. For very young children or individuals who cannot read, picture optotypes or matching games with Landolt Cs are often used. The selection and presentation of optotypes are crucial for accurate diagnosis and prescription of corrective lenses.