Article Date: 2/1/2001

PROGRESSIVES
How Progressive Do You Want To Be?
These steps may be the blueprint you need for greater PAL success.

By Irwin Shwom, O.D., R.D.O Everett, Mass.

Progressive addition lenses (PALs) have made our lives easier and richer. But how's your success rate? Success with PALs isn't an easy task without a consistent plan of action when fitting these lenses. I know that many of you leave fitting PALs to your technicians, but neither you nor your technician should miss out on these ideas to achieve more success with them.

Finding a scapegoat

After years of experience in both the opticianry and optometric ends of our field, I've discovered that many us find it easier to blame our patients for not adapting to PALs rather than to search for better solutions so they can adapt to these lenses.

For PALs to become the workhorses of our practice that they should be, we need only make sure we consistently follow a few steps when fitting patients with PALs.

Here are the seven steps that I follow:

  1. "scope out" the right patient candidates
  2. explain PALs to them
  3. examine and prescribe
  4. select frames that make the lenses work
  5. "dot" them
  6. fabricate them
  7. adjust them.

Once we've done all of these, then, and only then, can we assign to our patients the relatively simple task of getting used to PALs.

Scope out the right patient candidates

I've found that most successful PAL users need to present to us with some concern regarding their inability to visually function smoothly and completely with their emerging presbyopia. Initiate a full discussion with your patient about the alternatives of two pairs of glasses and lined bifocals, listing all the advantages and disadvantages, prior to recommending PALs. After having this discussion with patients, I've found that for most of them, PALs provide a more than reasonable visual alternative.

Patient candidates for PAL use fall into a couple different categories. For instance, patients who are considered:

Searching

You can fit monocular patients successfully with progressives at a cost. Even when we do everything correctly, those monocular patients who're in need of wide fields of view, especially at near, are limited by many of today's PAL designs. In our office, we fully advise successful monocular progressive users of the field limitations and demonstrate these limitations to them where possible.

Strabismic patients who function monocularly fit into the above description. Despite some limitations, they can be successfully fitted with PALs. Intermittent and large phoric patients have shown relatively large failure rates. A basic tenet of successful PAL fitting has been, "Both eyes and the nose need to be pointing to the same target at the same time," and they don't always meet that criterion.

Head tilting patients are all right as long as they're constant and repeatable. Patients with mild to moderate degrees of head tilting from vertical can be successfully fitted with PALs as long as this is a normal and natural position for them to remain in.

Discourage patients who drive at night and lift their chin upward to decrease the glare of oncoming headlights from using progressives.

Explain them

Negative selling isn't something I like to do, but it's important to explain up front things that PALs don't do well.

Backing up a car isn't easy for PAL users. If you were to look way back over your right shoulder now, you'd notice how your chin moves up. Think about what occurs when we raise our chins with a PAL. Good for reading, bad for distance.

Lying down while watching television isn't easy, either. When we lie on our backs, our chins again rise. This helps with reading, but unless a television is mounted at or near the ceiling, we're now looking out of the reading/intermediate portion of the progressive.

For long-term, detail tasks, PALs aren't necessarily the best option. Although we've made great strides to a truly wide field of view for near tasks, especially in higher add powers, we know that we've yet to reach optical nirvana. The relatively limited width continues to create visual comfort issues for even my happiest patients.

I've still found nothing more comfortable for a uni-distance focal length task than to have a pair of single vision near-only glasses to read with for extended periods of time. In situations like this, I can continue to feel comfortable prescribing progressives. But in this situation, you have a great opportunity to offer a pair of prescription readers as appropriate adjunctive therapy.

Active patients

Rock climbing, hiking, cycling and some racquet sports are also difficult for PAL users. Odd head tilt requirements along with the need for quick eye movements consistently remain on target for single clear vision. Given these conditions, I'd fit a PAL only to an experienced wearer, but never to a rookie.

Unfortunately, the lens design always has an area that is out of focus for the patient. We all know that the optical engineers in our field have done a great job of designing today's new progressives, but they know and share with us their frustration in not being able to make the perfect progressive.

Unwanted, but inherent, astigmatism exists in every PAL design. Most of the unwanted power is located in the lens in both the nasal and temporal portions of the intermediate and near segments of the lens. As opposed to waiting for patients to tell me about the "blur" they see at intermediate and/or near, I demonstrate that to them up front.

I use a standard Amsler grid chart and have the patient move the glasses closer and farther from the chart to demonstrate the "by design out of focus zones" in the PAL. Doing this has dramatically cut down on my patients' objections to peripheral blur at near symptoms.

Examine and prescribe

A great refraction has no substitute, regardless of the technologies that we use to get there. Knowledge and comfort with your refracting and prescribing techniques are a must. This is no time to try "new" techniques on the refracting side of the table.

Prescribe your full-powered prescription for both distance and near, making sure not to add "extra power" at either distance or near for compensation. The compensation has already been done for you in most new lens designs.

In prescriptions with greater than 5.00D of power, know the distance at which you're refracting and the vertex distance at which you'll fit your patients. Here's the opportunity to prescribe "small" changes in the final prescription to get your desired visual outcome. We do it with contacts, so we can also successfully do it with PALs.

I've found that the unequal image size found in anisome- tropic patients creates about the same amount of post fitting frustration as conventional lined bifocals.

Patients who report classic difficulties while reading with lined bifocals will report the same effects with PALs. However, I've found that prescribing a slab-off compensatory prism, a widely underused but successful option, fixes this problem.

Also, I've had great success fitting patients who meet all standard fitting criteria, but who also have a relatively large amount of astigmatism. With today's super-calculated, computed and manufactured PALs, astigmatism doesn't pose a big problem for a successful fitting.

Select the best lens

How do we know which PAL to fit? To be honest, this is where you have to try them yourself and decide. My lens representatives do an excellent job of providing us with information on the comparable strengths and features of their company's lens designs. However, I've found that I need to try them on myself first to "see" what they're trying to tell me, then decide where I can best use the lens.

Make it work

Use adjustable nose pads. Unless you have a super adjustable, pliable, fixed bridge resin frame, always fit PALs with frames that have adjustable nose pads. You need the feature of adjustability while dispensing to make those last-minute tweaks on the completed spectacles. You also need to use adjustable face form and pantoscopic tilt capabilities.

Choose frames that either incorporate this feature or that you can manipulate at either the fabrication or the dispensing time. These types of frames have the ability to be rounded to the face and create between 10 to 15 degrees of pantoscopic frame tilt. You should be discouraged from using any frame that you can't reasonably bend or won't maintain a position.

Once you've found the frames that work best, supply them in multiple bridge sizes in your dispensary. As I walk into my own dispensary, I see many frame shapes that look nice, but similar, from a distance. I'll carry the same effective shape frame in multiple sizes but each one has the nose pads mounted in a different place on the frame.

For instance, if I'm looking for an oval-shaped frame, and the one I've initially selected causes the frame to sit too high on the patient's face, I just look for the same type of frame that has the nose pads mounted a little higher on the frame. This feature causes the frame to drop a bit, creating a better fitting advantage.

Don't purchase a frame that you'd use for fitting PALs if you can't make adjustments smooth-ly, fully and without breakage. Some frame designs and materials make adjusting more challenging than necessary.

Dot 'em

You've heard it for years: "Place the optical center of the patient's lenses directly in front of his line of sight for the required tasks." Fitting PALs is no different. The concept of dotting the optical center is a necessary technique we all must master.

Remember that the patient's right eye sights his left eye and the patient's left eye sights his right eye. Don't cross sight because that causes parallax, resulting in a false optical center and possible PAL rejection.

Make sure you're at the same height as your patient when dotting so that you see eye to eye. Either get up to his height or have him come down to yours.

Have the patient place the adjusted frame on before and after dotting in the position that he's most likely to wear them. Before I asked patients to do this, I consistently had a high rate of PAL failures.

Think about it: I want frames to fit certain ways, so I place them where I think they should be on the patient's face. Patients listen to me in my office, but once they've left, the real world takes over, and they adjust the frames to their comfort level.

Of course, this doesn't always mesh with how I've adjusted the spectacles. At the time of dotting, I'm as insistent as I can be that my patient place the frame on his nose and face in a location that they "most likely" will end up using them. In most situations, I can be kept in the positive column of PAL success by making small, easy-to-do compensations on frame fit.

Dot the patient's pupil location in a consistent manner. I've found that searching, locating and dotting the nasal aspects of the patient's pupil has helped a lot in making me accurate with proper centration of the finished distance PAL.

Fabricate them

With today's patternless edgers and computerized lens layout technology, this is the easy part. Let the machines do it. Uncut finished PAL lenses come with marking dots that are easy to locate and use.

After you've used the standard layout and blocking techniques, edge, finish and insert the completed lens like any other simple single vision job. Nothing special is required to edge and finish these in your own in-office lab.

Inspect the finished job optical center using the lens manufacturer's layout charts and against the dotted sample lenses. Should your dots not line up with the prescribed fitting centration, stop and either re-align the lenses in the frame or throw them away and start again. This isn't a situation where close is good enough.

Adjust them

After you've completed and inspected the finished eyeglasses, ensure that the finished product is "bench fitted" with 10 to 15 degrees of pantoscopic tilt.

Times are good

We've never had a better or easier time to prescribe, fit and troubleshoot PALs. Today, most progressives work well "out of the box." Certainly, some work better than others, and we've all developed our favorites. With the unveiling of the next generation of lenses fitting progressives just gets easier.

Dr. Shwom's brother, Leonard C. Shwom, O.D., R.D.O., contributed to this article.

Dr Shwom is in private practice in Everett, Mass. He's an associate professor at the New England College of Optometry in Boston. If you have your own "Tricks of the Trade" on progressive addition lenses, please send them to: Irwin M. Shwom, O.D., R.D.O., 421 Broadway, Everett, Mass. 02149-3435. Phone: (617) 387-1904. E-mail: bubba421@aol.com.

New Directions for PALs
An ophthalmic lens expert forecasts the next big step for PALs.

By Joseph L. Bruneni,
Torrance, Calif.

Have you been wondering about the latest changes in progressive addition lens (PAL) designs? Well, here's a brief rundown of what's been happening in this advanced lens category. The past 18 to 24 months have seen major changes in PAL designs.

The first such change was prompted by the fashion trend toward smaller, vertically narrow frames. Trying to dispense a conventional progressive design in one of the popular new small retro frames became a blueprint for disaster because the narrow vertical height of the frame or mounting cut off much of the reading portion of the lens. Recognizing a new market, American Optical produced their Compact lens with a progressive channel shorter than anything available at that time.

Since then, other short channel PALs have become available, such as the Hoya Hoyalux GP, Pentax AF Mini, Rodenstock Progressiv series, Kodak Concise and Sola Solamax, to name just a few.

The next major change came with the "position of wear" concept in which the manufacturer or laboratory alters the O.D.'s prescription to compensate for the way the lens is positioned when worn by the patient. The prescription changes are subtle, but they do seem to provide enhanced acuity for the patient.

Another example of an advanced progressive concept is the long-awaited cast-to-prescription progressive from Johnson & Johnson. The new lens from Johnson & Johnson places half of the progressive addition curves on the front surface and half on the back surface of the lens. According to Johnson & Johnson, the result of this hybrid approach is a considerably wider field of view for intermediate and near.

SOLA recently introduced a totally new progressive design called Solamax, featuring a short channel with an intermediate zone considerably wider than conventional progressives. SOLA President Brett Olson recently told a laboratory audience that the non-adapt rate for this design is running .006%. He stated, "SOLA believes the future in progressive design will be specific progressives for specific tasks. The concept of fitting every patient with a general purpose progressive design will be outmoded by progressives that are designed for specific patient lifestyles."

He added, "Future products from SOLA will focus on performance, technologies and fashion. We plan to continue expanding our family of progressives with lenses designed for the patient's custom needs."

Rest assured that Sola won't be the only company seeking to produce newer, more advanced progressive designs. At a recent OLA convention, a new type of generator was unveiled that could potentially permit laboratories to produce lenses that would have progressive curves placed on the back surface of the lens. The same machine can also produce atoric back surfaces, something labs are unable to surface with conventional equipment.

As a result of these advancements in progressive designs, coupled with the extraordinary improvements in laboratory processing equipment, the concept of producing progressive lenses specifically designed for each patient's lifestyle is close to reality. This continuing advancement of progressive lens design may create a somewhat confusing range of choices for eyecare professionals, but the long-term beneficiaries are the patients who wear these sophisticated lenses.



Optometric Management, Issue: February 2001