If a patient is presbyopic and wearing lenses that correct for distance, computer, and up-close vision, what type of lenses are they using?

The correct choice is progressive addition lenses, which are specifically designed to provide a smooth transition between multiple lens powers, accommodating different focal distances for presbyopic patients. These lenses allow individuals to see clearly at various distances—far away, at arm's length (like a computer screen), and up close for reading—without needing to switch between different pairs of glasses.

Progressive lenses generally feature no visible lines between the different lens areas; instead, they gradually change from one prescription to another across the lens surface. This design mimics natural vision and provides a more aesthetic option compared to bifocals or flat-top lenses, which have a distinct line separating the different viewing areas.

Single vision lenses, on the other hand, only provide one focal power and wouldn't accommodate the multiple vision needs of a presbyopic patient requiring corrections for distance, intermediate, and near vision. Bifocal lenses and flat-top lenses, although effective for certain presbyopic needs, have a defined separation between the two lens powers, which does not allow for intermediate vision correction. This makes progressive addition lenses the appropriate choice for someone needing comprehensive vision correction across various distances.