In lenses, what does the ‘add’ power signify?

The ‘add’ power in lenses specifically refers to the additional magnifying power needed in multifocal lenses, such as bifocals or progressive lenses, particularly for activities like reading. This power is incorporated into the lower portion of the lenses to assist individuals with presbyopia, a condition that affects the ability to focus on close objects as one ages.

In a multifocal lens, the ‘add’ power is what allows for a smooth transition from distance vision to near vision, enabling users to have clear vision both far away and up close. The ‘add’ is measured in diopters and signifies how much additional strength is required for the lower segment of the lens to accommodate tasks like reading, sewing, or any close-up work.

Understanding the role of ‘add’ power helps individuals choose the right lenses for their visual needs, especially when they require different strengths for varying distances.