What does the term "additional amount of plus power" refer to?

The term "additional amount of plus power" is primarily associated with the extra lens power required for near vision tasks in individuals who are presbyopic or have difficulty focusing on close objects due to age-related changes in the eye. This concept is critical for optometrists and ophthalmologists when determining the appropriate prescription for reading or other tasks that require close-up vision.

When a patient requires an "additional amount of plus power," it indicates that their base prescription (for distance vision) needs to be augmented to allow for clear vision at shorter distances. This is particularly relevant when the standard distance correction may fall short for activities that necessitate fine detail work, such as reading, sewing, or using a computer. Understanding this additional power helps in providing the best possible vision correction tailored to an individual’s specific needs.

In contrast, the other options—correction for distance vision, adjustment for astigmatism, and measurement of lens thickness—address different aspects of vision correction or lens characteristics and do not align directly with the specific requirement for enhanced near vision.