Eyeglasses come in a various types. This includes a single-vision lens with one power or strength over the entire lens, or a bifocal or trifocal lens with multiple strengths over the entire lens. But while the latter two are options if you need a different strength in your lenses to see far and near objects, many multifocal lenses were designed with a visible line separating the different prescription areas in the eyeglasses.
If you prefer a no-line multifocal lens for yourself or your child, a progressive additional lens (PAL) might be an option.
What are progressive lenses?
PALs are a type of multifocal lens specifically for people who need corrective lenses to see distant and close up objects. To put it plainly, these lenses allow you to see clearly at multiple distances without a bifocal line.
The need for a progressive lens increases with age. By the age of 35 or 40, many people have difficulty focusing their eyes on nearby objects. This is known as presbyopia, and to compensate for this focusing problem, some people wear single-vision eyeglasses for distance, as well as reading glasses for close up.
While this approach can work, PALs provide a simpler, more convenient solution to age-related vision problems:
The upper section of a progressive lens provides the strength you need to see clearly in the distance.
The lower section provides the strength you need to see clearly up close.
The middle section helps you see clearly at intermediate or middle distances.
These lenses provide a gradual transition in strength from top to bottom.
In short, Progressive lenses are more suitable if you have a prescription which has a combination of Distance and Near Vision powers and you follow an active lifestyle.