What does a prism diopter measure?

A prism diopter measures the deviation of light that occurs when it passes through a prism. This measurement indicates how much the light is bent or deviated from its original path due to the prism's angle and refractive properties. Specifically, one prism diopter corresponds to a deviation of one centimeter at a distance of one meter from the prism. This is important in optometry because prisms are often used in lenses to help align the line of sight for individuals with certain visual disorders, particularly strabismus or other binocular vision issues.

Understanding prism diopters is crucial for optometric technicians when working with patients who may require prism correction in their eyewear. It helps to ensure that the lenses are effective in improving binocular vision and reducing symptoms such as double vision.