What is the primary purpose of measuring segment height in eyewear fitting?

Measuring segment height is crucial in eyewear fitting primarily to ensure comfort while viewing, particularly for those using multifocal or bifocal lenses. The segment height measurement determines the vertical placement of the reading or near portion of the lens in line with the wearer’s eyes. This placement is essential for achieving optimal visual clarity and comfort when looking at nearby objects. If the segment is positioned too high or too low, it can lead to visual strain, discomfort, and difficulty transitioning between viewing distances, which undermines the functionality of the lenses.

While considerations such as lens integrity and aesthetics play a role in eyewear fitting, they are secondary to the paramount need for visual comfort. Proper segment height facilitates a seamless experience in viewing tasks, thus enhancing overall satisfaction with the eyewear. Aligning with fashion trends may also be important to some wearers, but the primary focus remains on achieving the best optical performance for everyday activities.