Staff Smarts Article

Useful information, answers to common questions, and more.

Questions and Answers About Digital Lenses

Why is Digital better than conventional?

With the conventional (also known as the traditional surfacing), laps or tools are used and can only create spherical and cylindrical curves.  No type of design can be placed on the lens.  You also have to work within the constraints of the corrected base curve system.  With the traditional surfacing system, aberrations are moved from the center to the edge. With Digital surfacing a proprietary design can be placed on the front and/or back and depending upon the design, both central and peripheral vision can be positively impacted.  The designs are optimized to attain the correct base curve for maximum vision based on the patient’s Rx.  A lens that is digitally surfaced will have wider fields of view, will be more accurate, will bring out the potential in the lens design and is the most advanced lens technology today.

What makes Dual Digital by Essilor better than the competition?

Dual Digital by Essilor offers better vision because it offers better overall vision by focusing on both central vision and peripheral vision.  Only calculation technologies combining 2 complex surfaces can reduce aberration up to 30% and provide wider distortion free in all vision area: far, intermediate and near.

What is better FBS or Dual Digital?

FBS technology starts with a single vision spherical lens and the design is placed on the back.  FBS offers good vision and is value priced and is a very cost effective way to make a PAL.  The emphasis is on central vision rather than peripheral vision.  There is a balance between controlling good focus and reduction of distortion.  FBS is limited to 1 design so there isn’t a lot of flexibility.  For more on Dual Digital, see answer to question 2.

What impact does Digital surfacing have on the design?

Only the Digital surfacing process can create a design, the traditional surfacing procedure cannot.  The design and process is controlled by sophisticated computer files called point files.

Is there extra turnaround time for digital designs?

No. Digitally surfaced lenses offer the best available lens products and technology and take no longer than traditionally surfaced lenses.  In some cases the turnaround time will be quicker.

Is there any tool made that can measure or show the width of channel made with FBS?

There is no measurement device to measure width of channel however this should not be a concern.  Lens designs created with the digital process will offer the patient enough area to use the intermediate area of the lens.

Do any cut out charts change with the new digital lenses vs. conventional lenses?

Cut out charts should only be used as a guide.  Depending upon the digital lens style and the Rx, blank size used is based on the base curve.  Generally, the higher the Rx the smaller the blank size.  In addition, with some digital designs the progressive length is based on the size of the frame so trying to find the exact area to check the add power may be impossible which is why in this case you should verify the add power that’s engraved on the lens.

If you’re putting a design on the back, why can’t I tell you how long to make the progression?

You don’t have to worry about his at all.  Complex calculations go into every lens design.  Based on the design and in some cases the frame size, the progression will be optimized based on both of these factors to give the patient the best vision possible.

Are there any differences in fitting/adjusting with digital products?

As mentioned in question 7, blank size can be any issue.  In addition, you cannot specify base curve because to obtain maximum vision, a specific base curve is used based on the Rx.  Deviating from this can compromise the optics.  Some Digital designs such as Varilux Physio Enhanced and Shamir Autograph have the Rx compensated based on position of wear.  Please be aware that in these cases the Rx you order and the Rx you receive will be slightly different.

If the optics are better but my lower Rx patients don’t get a WOW, how do I explain it?

Since digital lenses came onto the market in 2005, lens manufacturers conditioned the industry that patients will get a WOW when they initially put on their digital lenses.  In reality, we know this won’t happen in every case.  It’s important to note that when your patients initially put on their new glasses they are “testing” them out in a “controlled” atmosphere in your office.  They may not experience a WOW under these circumstances.  The patient may discover the WOW when they leave your office and do routine tasks at home such as working on a computer, reading, working around the house, etc.