Focus on Fundamentals

When it comes to progressive lenses, knowing what elements lie within them—plus how to describe their inner workings with the correct terminology—will allow the eyecare professional to confidently explain the lenses’ abstract and invisible technology.

While each spectacle lens maker is today continuously creating new terminology and proprietary words to elevate the description of their lenses, focusing on fundamental terms can simplify the patient education process—and ensure that they understand what you are explaining, including their own anticipated visual experience. This consistent, simple approach will encourage patient confidence in the optician’s guidance in selecting the most suitable lens design for their visual needs.

Progressive lenses—also referred to as multifocal lenses or PALs (progressive addition lenses)—are used to correct vision at multiple distances, providing a progression in power from the wearer’s prescribed distance Rx into intermediate and then near vision seamlessly, without any outwardly visible aesthetic characteristic of the power change within the lens.

Fundamental Terminology

When it comes to the multitude of progressive lens styles available today, the offerings can be overwhelming. Every lens vendor offers various designs, each with its own unique characteristics and benefits. Regardless of brand or style, the following terms remain the fundamentals of explaining what lies within a progressive lens.

➤ Distance Vision Zone: The upper portion of the lens is set directly in front of the wearer’s pupil. It’s a space optimized for clear vision in the distance, such as when looking at objects far away or driving.

➤ Intermediate Vision Zone: Slightly below the optical center is the intermediate distance. This is the portion of the lens designed for the speedometer of a car, laptop computer,* or viewing objects at arm’s length.

[*It is important to note that a progressive office or computer lens design is a better lens design for desktop computers. The upper portion of the lens is set for optimal intermediate distance straight ahead and the wearer need not tilt their neck back to reach the intermediate zone.]

➤ Near Vision Zone: This is the lower portion of the lens that provides clear vision for close-up tasks such as reading or using a smartphone. It has the strongest power for near vision correction.

➤ Corridor: The corridor refers to the vertical area on the lens where the power transitions smoothly from the distance zone to the near zone. A longer corridor allows for a wider range of vision in different distances but can make the progression longer to reach the reading area.

➤ Adaptation Period: The adaptation period is the time it takes for wearers to adjust to progressive lenses. It may take a few hours or days to get used to the different focal points and head movements required to find the clearest vision.

➤ Free-form or Digital Progressive Lenses: Use advanced computer-aided calculations to customize the lens layout based on the patient’s Rx, frame, and fitting measurements. Combined with advanced surfacing technology, the resulting progressive lenses optimize the visual performance by reducing peripheral distortion and aberrations in the lenses. Wearers experience superior visual experience and reduced image distortion or discomfort.

Selecting Lens Layout

Selecting the correct progressive lens layout can be the difference between a satisfied wearer and a non-adapt. Begin by asking your patient about their activities, lifestyle, and hobbies to make the most suitable recommendation. Ensuring that even a repeat progressive patient has been paired with the perfect lens layout for the current time in their life will show the ECP’s commitment to elevated care.

➤ Regular progressive layouts are ideal for frames with a fitting height of 18mm or greater. They offer a smooth transition from distance to near. The lenses are ideal for general day-to-day activities—compatible with active, athletic wearers and those who spend lots of time outdoors and if a driving or distance Rx is required.

➤ Short progressive layouts are ideal for frames with smaller vertical dimensions. The lenses offer a full progression in power, distance, intermediate and near, but shorten the transition into the near zone. A short corridor progressive lens layout is best suited for a fitting height of 14mm or less.

➤ Ultrashort progressive lens layouts are ideal for any patient making the switch from a bifocal to a progressive. The ultrashort corridor length offers the appearance of a no-line bifocal and removes the image jump characteristic of a bifocal because even though the progression in power is rapid and ultrashort, it still exists within the lens. Ultrashort corridor lenses can also be used in frames that require a fitting height of 12mm or less.*

[*Optician’s tip: Trying to put a progressive lens in a super-narrow frame that would require a fitting height of 12mm or less isn’t ideal and the wearer can struggle with the micro reading zone.]