In multifocal lenses, the segment height is most critical for which type of vision?

The segment height in multifocal lenses is particularly critical for near vision because it determines the positioning of the reading segment in relation to the wearer's eyes. Proper segment height ensures that when the wearer looks down to read or engage in close tasks, their line of sight aligns with the optical center of the near vision segment. This alignment is essential for achieving clear and comfortable vision at close distances, which is the primary function of the near portion of multifocal lenses.

In contrast, the other types of vision—distance, intermediate, and peripheral—are not as directly impacted by the segment height. Distance vision relies more on the top portion of the lens, while intermediate vision depends on the central part of the lens, making segment height less critical for those areas. Peripheral vision is generally concerned with the overall lens design and fit rather than the specific height of the segment. Therefore, understanding the function of segment height in relation to viewing distances underscores its critical role in enhancing near vision in multifocal lenses.