Which feature is characteristic of multifocal contact lenses?

Multifocal contact lenses are specifically designed to help individuals who have presbyopia, a condition that typically affects those over the age of 40, which makes it difficult to focus on close objects. The characteristic feature of multifocal lenses is that they incorporate progressive power, allowing for different levels of magnification for various distances. This means that wearers can see clearly both at a distance and up close without needing to switch between different pairs of glasses or contact lenses.

While single vision lenses correct for only one distance, multifocal contact lenses blend multiple prescriptions seamlessly within the same lens. This progressive design mimics the natural vision adjustment that occurs with the eye, providing a smoother transition between seeing things at varying distances. Using flat design or high water content does not specifically define multifocal lenses; these features can be associated with various types of contact lenses depending on their intended use and material properties, but they are not unique to multifocal lenses.