ABO NOCE Practice Test

The longest vertical portion of the lens corresponds to the measurement known as the "B measurement." The B measurement refers to the lens height, which is the distance from the geometric center of the lens to its deepest vertical point. This measurement is crucial for various fitting and positioning aspects of the eyewear, ensuring that the optical center is aligned with the wearer's line of sight and that any prescribed prism is properly positioned.

In the context of opticianry and eyewear fitting, understanding the B measurement helps in maintaining visual comfort and aesthetic considerations. It ensures that the lenses will sit comfortably within the frame, providing the appropriate coverage for the wearer's eyes. This measurement is especially important in progressive lenses, where the alignment of the lens' various zones is critical for optimal vision across different distances.