L&T: RxPertise

Jan
2010

Premium Free-form Single Vision:

The ‘Wow’ of Ultimate Seeing


Photograph by Ned Matura

When we fit conventional ophthalmic lenses in accordance with proper, corrective curve guidelines, they will deliver the excellent optical performance their designers intended. We’ve all learned this proper way, either in school or on the job. But how many of us practice proper measuring and fitting of single vision lenses in our offices, every day, with each and every client? If you’re like me, probably not much. Most ECPs have, in the absence of client complaints, become complacent about the need to practice and fit corrective curve lenses properly. The result is a diminishment of a lens’ true performance potential.

This “twilight zone” of reduced lens performance is essentially an amalgam of many intended and unintended departures from strict compliance with good, corrected curve measuring and fitting techniques. The bad news resulting from these departures is that we ECPs, over the last 25-plus years, have routinely delivered less than optimal single vision lens performance. The good news is that although we may have been unintentionally negligent, we set the stage for premium, free-form single vision lenses to deliver the biggest perceived improvement in ophthalmic lens performance in almost 100 years.

The Big “Wow” of Premium, Free-form Single Vision Lenses
Over the past year or so, doctors and dispensers have increasingly been hearing about patients’ positive reactions to their first pair of premium, free-form single vision (FF SV) lenses. The comments typically range from a simple, “wow” to “unbelievably clear” to “I haven’t seen this well in years!”

Why do these premium lenses inspire such positive comments? There are several reasons:
  • The extreme high precision of free-form surfacing, which can produce lens surfaces over 100 times more accurate than traditionally generated lenses.
  • Sophisticated lens design software that allows correction levels beyond those of even optimally fitted, corrective curve lenses.
  • For the first time, it now becomes possible to optimize sphero-cylindrical prescriptions in their peripheral regions. Remember, corrective curve theory never provided for simultaneous correction of two power meridians, as found with sphero-cylindrical corrections.
  • Lens material choices can be freely chosen, i.e., lens index, photochromic, polarized, etc., almost without traditional availability considerations.
  • Fitting values that differ or depart from default or assumed values in pantoscopic tilt and vertex distance are possible to compensate for in the lens design software.
  • Lens design performance can be further optimized or enhanced using personal factors such as frame size, shape, frame curve, horizontal PD and monocular pupil heights.
  • With some designs, base curves can be individually specified. This mean that a particular frame’s face form curve can be best maintained through use of a base curve that may depart from traditional corrective curve guidelines. Premium, free-form SV lens design software can compensate for this in the lens’s design calculations.

The real “wow” clients are exclaiming about with premium, free-form single vision lenses is actually the sum of the following three factors:
  1.  How in the past, we lost our way with respect for the proper fitting of corrective curve lenses.
  2.  How ECPs detoured into the “twilight zone” of reduced lens performance by fudging lens curves, materials and designs, in order to deal with the whims of eyewear fashion, and by so doing, facilitated our patients getting “used to” substandard optics.
  3. How the precision, sophistication and personalization possibilities of new, digitally surfaced, free-form optimized single vision lenses can surpass the benchmarked lens performance standards of lens designs now nearing almost 100 years old.

Positioning Premium FF Single Vision Lenses to Patients
ECPs should ask themselves when was the last time they were excited to suggest anything beyond AR that would significantly improve the clarity of a single vision lens? Considering that premium, FF SV lenses are only modestly more expensive than quality finished lenses similarly optioned, the price difference they will request for these truly revolutionary lenses should encounter any resistance. If one is lucky enough to be dispensing a client’s first pair while also presenting the same to another, the “wow” reaction heard will no doubt “seal the deal” right away.

The additional time required when determining custom measurements for these premium lenses is sure to be greeted with such patient comments as, “I don’t remember you taking these measurement before.” Take the opportunity to answer with an explanation of how these advanced lenses are different from the older designs they’ve been fitted with before. These additional measurement opportunities, referred to as “patient contact points” (thank you to Anthony Fulco of 21st Century Optics for this terrific term), are essential in enhancing the atmosphere of professionalism and trust needed to differentiate a practice within today’s competitive eyewear market.

Ultimate Seeing
The broad arrival of premium, free-form single vision lenses, has, in my opinion, come to our market a little late. For those ECPs who’ve tried and questioned the value of premium, free-form progressives, I ask you to give these premium SV lenses an earnest try. For your most value conscious or skeptical progressive wearers, try packaging a pair of premium FF SV lenses with their next progressive purchase and position them as the ultimate TV eyewear. What progressive wearer doesn’t slide their eyewear down their nose to view their new, high-definition TV better? And for any prescription containing more than 0.50D of cylinder power, presenting this class of premium SV lens is an absolute no brainer. Everyone I’ve fitted in these ways has requested that I be sure to recommend this technology for all their future eyewear purchases.

The next time a client says they don’t “need” new glasses because their prescription hasn’t changed, talk to them about enjoying the new, premium free-form single vision lenses that deliver the sharpest vision ever. The culmination of over 200 years of ophthalmic lens design, they are truly the ultimate in sight.


What’s New in Premium Single Vision

This L&T roundup of the latest free-form, single vision lenses includes fitting tips for dispensers.

Augen HD
Augen High Definition single vision lenses are aspherized along one or two meridians on the front surface based on prescription, ensuring wide, clear, natural vision for the full range of single vision wearers. The patented design is aspherized for sphere power for prescriptions with no or low cylinder (0.00 to -0.50), and for both sphere and cylinder powers in prescriptions of 0.75 or above. In addition, Augen HD single vision lenses provide flatter curves for all prescriptions, resulting in better cosmetics and thinner centers in plus prescriptions and reduced edge thickness in minus prescriptions.  Augen High Definition lenses are made with proprietary digitally surfaced free-form molds to guarantee each lens delivers the precise characteristics intended by the design team. The optical performance of the lenses is further enhanced by optically pure materials such as Trivex from PPG.

Essilor 360 DS SV
The Essilor 360 Digitally-Surfaced (DS) SV lens is an excellent choice for practices concerned with maintaining familiar fitting and processing requirements. Included is your choice of Crizal Alize or Crizal Avance with Scotchgard Protector. The lens design pole of 360 DS SV lenses is coincident with the lens’s optical center, ensuring easy fitting. Focimeter verification is done at the optical center. Material choices include standard plastic, 1.50 Transitions, Airwear and 1.74 index.

Hoya NuLux EP

Unique among the current crop of premium FF SV lenses, Hoya NuLux EP are the only lenses featuring FF, DS processing on both the convex side as well as the concave side. Hoya claims this allows superlative lens performance. Fitting is done with the lens design pole placed in front of the eyepupil and is defined by engraved circles in the same position. Focimeter verification is done at the MRP, which is between the engraved circles. Material choices include 1.67, 1.67 photochromic and 1.70 index.

Rodenstock Impression Mono and Nexyma

As with the other lenses, Rodenstock’s Premium free-form SV lenses includes designs for distance vision. And, currently unique in the USA market, Rodentsock provides a premium FF, SV lens called Nexyma, that is optimized for near vision rather than distance vision. Although just re-entering the U.S. market, Rodenstock FF SV lenses are available with both POW compensation, as well as ECP specified personalization. Availability includes most indexes, photochromic and polarized options. The lens design pole is fitted online with the eyepupil and is inline with the lens engravings. Focimeter verification is done at the MRP, which is between the engravings. The Nexyma near vision lenses are available for reading distances of either 16 inches or 33 inches. Nexyma lenses are currently available in standard plastic.

Seiko Super MV 1.67
The Super MV 1.67 from Seiko Optical Products of America is a double-sided aspheric single-vision lens that combine Seiko’s patented aspheric front design technology with advanced free-form lens processing on the back. The unique combination of a patented low base curve and free-form aspheric back-surface design virtually eliminates power error, distortion and marginal astigmatism, according to Seiko. The front surface includes Seiko’s exclusive 10mm spherical fitting button. The free-form back surface provides precise aspheric/atoric compensation calculated for the patient’s individual Rx. Unlike traditional aspheric lenses, which compensate for the primary aberrations in the spherical power, Super MV lenses correct these aberrations throughout the entire cylindrical axis, virtually enabling the edged lens to have “optical center vision” everywhere. The result is clarity of vision throughout the entire lens, even in Rxs with high power and cylinder.

Shamir Autograph II SV
An easy to fit premium SV lens, featuring a wide range of included fitting values. This design, therefore, is very easy to dispense, and does not require or use additional position of wear values (POW), such as pantoscopic tilt, frame curve or vertex distance. The optical “pole” of the lens design is online with the engraved fitting circles. Shamir’s propreitary Eyepoint technology will automatically calculate proper thinning prism, which is often required where the eyepupil is located significantly above a frame’s mechanical center. In this design, ECPs should not pay attention to the lens’ optical center, which can be found with a focimeter. Proper, individual placement of the lens’ engraved circles is the primary fitting consideration. Lens verification is done with a focimeter at the MRP, which lies between the engraved circles. All material indexes, photochromic and polarized options up to 1.67 index are available.

Zeiss Individual SV
A sophisticated and personalized premium SV lens, Zeiss Individual allows for ECP input of personalized POW parameters, including VD, Pantoscopic tilt and frame face form angle. Although the Zeiss Individual optimization program can determine the appropriate base curve required for the above, ECPs have the option to select an alternate base curve within 2 diopters of the program’s chosen default value. The Individual lens MRP is placed 4mm below the eyepupil. Lens engravings and focimeter verification occur at this MRP, which is between the engravings. Most material indexes up to 1.67 index are available, except Trivex. Of course, polarized and photochromic options are included.
—BS

 

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