PAL Strategies for the
Clinical Optical Dispensary
How to provide a superior visual experience
for your presbyopic patients.
BRIAN D. ROSENBLATT, O.D.
Today's ophthalmic practitioner must possess the qualities of both a healthcare provider and an optical lens expert. This duality is seen clearly in the area of presbyopic eye wear. We must ensure the highest quality of care including diagnosing and treating the ophthalmic health and addressing the optical correction.
We are also responsible for educating our patients so that they can make intelligent healthcare decisions. In this article, I'll explain how clinical and optical staffs can contribute to increasing patients' satisfaction with progressive addition ophthalmic lenses
Plant the seed
In your reception area, you and your staff can "plant the seed" in a patient's mind regarding various eyewear options. Use displays and brochures that describe the different options and the applications of each. Many patients bring these brochures to the examination room and ask if a certain option is appropriate for them.
Therefore we must educate patients in the exam room and when transitioning them to the optician; finally we must provide a model for the optician to educate the patient. An important concept to keep in mind is that the educational process associated with the prescription and subsequent sale of any optical device begins in the examination room. It continues as the patient's care is assumed by the optical staff.
The evaluation begins
Once the presbyopic patient enters the examination room, the evaluation of his or her ophthalmic needs truly begins. A thorough history, including occupation, avocations, and observation of the patient's posture is helpful in your treatment plan.
For the patient who may be a multifocal lens candidate, his natural head positioning is paramount for proper optical center alignment. Note any physical restrictions or requirements.
An accurate refraction is important. Carefully evaluate prescription changes. Checking the difference from the patient's habitual prescription to his new refraction will provide a great deal of information to improve prescription change adaptation. If the change in refraction is minor, visual complaints may be directly related to their current presbyopic lens design and fitting.
As part of our approach to refractive error, we must understand the patient's visual needs such as driving, computer use, and near point demands. Is the patient a progressive lens candidate? Does he require a high-index material to reduce the thickness of his eye wear? What coatings are available to enhance the comfort and cosmetics of the patient's eye wear?
Your time to shine
At the conclusion of the comprehensive eye examination, you should summarize your findings with the patient. A patient who understands her ocular condition is more likely to be compliant with your treatment plan. A well-informed patient feels that you are truly directing his care rather than just going through the motions to sell a pair of glasses. This is your moment to shine, to educate the patient and to explain your findings with a thought out assessment and treatment plan.
It's imperative that the clinician recommend eyewear options appropriate for every individual patient. Just as you would educate a patient on your plan of action for the treatment of his glaucoma, so must you approach the correction of their refractive error. Patients are usually not aware of the advances in lens designs for
presbyopia, ultraviolet blockers, anti-reflective coatings or new lens materials.
Don't be afraid to recommend options that will provide improvement in their visual experience. Hopefully, they hear of new advances in lens technology from you rather than from a neighbor who may have gone to another optometrist. Patients want you to recommend and prescribe, not offer an a la carte menu of choices for them to decipher.
Never prejudge a patient's ability to afford your recommendation. Allow them to make their own financial decisions and have an alternative contingency plan appropriate to their treatment.
Transition is the key
When you introduce the patient to your optical staff, review your findings with the patient and the optician. This provides a continuity of care as the patient leaves the clinical setting and enters your optical service. The optical staff must be familiar with the options available to your patient based on your prescription and treatment
recommendations. Summarizing the patient's case with the optician in his presence permits the optical staff member to become familiar with your treatment and appropriate patient education.
Educate your staff
Although you may have done an excellent job of making appropriate recommendations and transferring the patient from your care to the optical staff, the patient may still wind up with a less-than-optimal pair of spectacles. It's important that you share your knowledge with your optical staff as you learn of new lens designs, coatings and materials. In other instances, it will be your optical staff that learns about new lenses and materials before you do.
Hold regular meetings to discuss new options and their applications in your dispensary so that everyone remains current. Your optical staff is ultimately responsible for guiding the patient through the process of selecting the final lens design, material and coatings that he'll actually purchase.
Know your progressives
Today's progressive lens designs offer many advantages to patients, yet also exhibit some significant limitations. Their cosmetic benefit has been widely embraced -- presbyopes favor the "no line" bifocal appearance of these lenses to their lined predecessors. Additionally, an intermediate zone incorporated into the progressive channel enables the presbyope to function at a computer without requiring additional eye wear.
Progressive lenses are available in many different materials and indices of refraction. Anti-
reflection coatings have greatly improved the comfort and cosmetics of these lenses. The scratch resistance and surface cleanability of the newer anti-
reflective coatings are also improved.
Limitations of these designs include a reduction in usable near zone versus lined bifocal designs and peripheral distortion from unwanted astigmatism. Furthermore, all progressive lenses produce unwanted astigmatism that causes symptoms of peripheral vision distortion and optical movement upon head or eye movement. This visual disturbance, known as "swim," is a byproduct of the optics that produces the progressive channel. Swim and the need to move the head and eyes to see through the clear areas of progressive lens account for the majority of patient adaptation problems.
Dealing with the unwanted
Each manufacturer's lens design distributes the unwanted astigmatism over a single surface of the lens. Variations in the location of the astigmatism create hard and soft designs, higher and wider intermediate channels and wider near optical zones.
Older progressive lens designs were categorized as "hard," with concentrated areas of peripheral astigmatism positioned mainly below the 180 line of the lens. "Soft design" progressive lenses, usually newer designs, tend to spread out the unwanted astigmatism even above the 180 line into the distance-viewing zone. This results in smoother transitions between distance and near but compromises larger areas of the lens with distortion.
Think of the unwanted astigmatism as piles of sand on the front surface of a lens; you can either distribute the unwanted astigmatism with a smaller base and higher peak (hard design) or with a larger base and lower peak (soft design). In both cases, you're not reducing the amount of unwanted astigmatism (distortion), but redistributing it.
Until now, repositioning the distortion had been the only option to lens designers. This is the major design limitation of using only one surface for the progressive curves. With one exception, all existing PAL lenses are single-surface progressive designs.
Another characteristic of current PAL designs is the approximate 1:1 relationship between add power and unwanted astigmatism. For each diopter of add power, there's a corresponding diopter of unwanted astigmatism (+/- 20%). So as the add power goes up, the intermediate channel width is reduced and peripheral distortion is increased.
Meet the designs
The leading PALs -- Sola's
Solamax, Rodenstock's Multigressive 2, Hoya's HOYAlux Summit ed, and Essilor's Varilux Comfort and Panamic -- are all excellent products that have made PAL fitting easier in the past few years. Our office has had great success with Varilux Comfort -- yet some patients are still unhappy with their
PALs. I gathered the information pertaining to the following designs from their respective manufacturers. Our office has not had experience with the Multigressive 2, Solamax or HOYAlux Summit ecp PAL designs.
Multigressive 2 by Rodenstock (www.rodenstock.com) is available in 1.50 plastic, 1.52 plastic Colormatic Extra
(Rodenstock's photochromatic product) and 1.60 plastic. It's available from +8.00 to -9.00 with up to 4.00D of cylinder, 4.00D of prism and adds of +1.00 to +3.50. Rodenstock describes its minimum fitting height as 18 mm.
Company designers used an aspheric front surface with an atoric back surface created by aspheric meridians. The lenses are available tinted, hard coated and anti-reflection coated. Because of the complexity of the design, the manufacturer suggests that customers allow approximately three weeks for delivery of Multigressive 2 lenses. Rodenstock says its technology yields immediate adaptation and cosmetically appealing lenses because of their use of flatter base curves.
Solamax by Sola (www.sola.com) is a general-purpose progressive addition lens designed with a near emphasis. Sola states that Solamax's combined features of a shorter effective corridor length and larger near zone that is "wider higher up," are appropriate for today's small fashion frames. The company says that it has a progressive corridor that widens rapidly into a large near zone, providing more clear near vision than its competitors' products that have short corridor designs.
Sola scientists used what they call "Design by Prescription" technology that incorporates varying the design of the distance and near zones for each base curve and add power. Solamax uses a soft design within the distance zone, combined with a hard design within the near zone.
To ensure comfortable binocularity during lateral viewing, Solamax was designed asymmetrically, with separate right and left lens designs. Sola also incorporated asphericity into this lens to minimize oblique power errors introduced by peripheral viewing. It's available with their patented DuPont anti-reflection coating, a six layer, anti-reflection stack that incorporates both hydrophobic (water repelling) and oleophobic (lipid retarding) layers. Material and power range availabilities were not available.
►HOYAlux Summit cd, the flagship PAL of Hoya
(www.hoyavision.com), uses Hoya's "Reduced Vertical Progression" technology to shorten the corridor, making this lens appropriate for today's small frame sizes. The progression corridor is the shortest of the products I've included, at just 11 mm. The lens can fit into a frame with a minimum B measurement as small as 24 mm. A minimal space of just 14 mm is required between the fitting reference point and the bottom rim of the frame and only 10 mm are required between the top of the frame and the fitting point. HOYAlux Summit cd is available in Hoya's 1.50, 1.60 and 1.70 indices. It's also available with Hoya's anti-reflection coating, Super HiVision Anti-Reflection. Spectrophotometer testing indicates a reflection rate less than 1%, therefore yielding a light transmission rate of greater than 99% with a gold reflex color. Hoya guarantees the coating for the life of the prescription.
Varilux Comfort and Panamic are two popular PAL designs by Essilor
(www.es-silor.com). Comfort is the fourth-generation PAL that the Varilux Corporation has introduced. It combines a high, wide near vision zone with a soft peripheral design. With a unique short progressive corridor length, 85% of the total add power is reached at 12 mm from the fitting cross. Because of the higher location of the near-vision zone, Essilor states that there's an approximate five-degree reduction in inferior eye movement to reach the full near add power compared to other standard PAL designs.
Panamic, Essilor's "premium PAL product," provides a wider near zone than Comfort with an emphasis on periphery softness and binocular vision of the lens design. Essilor's anti-reflection coating,
Crizal, is available with these two products. Crizal increases the light transmittance of the lens to 99%; with 1% reflectance and a green reflex color. It consists of a two-sided silica scratch-resistance coating, zirconium oxide containing anti-reflective coatings, and an outer hydrophobic layer on the contra-ocular surface. Varilux Comfort and Panamic are available in polycarbonate, 1.50, 1.56, 1.59, and 1.60 plastic indices, polarized, and Transitions lenses. Comfort is also available in glass and PhotoGray Extra Glass. Panamic is also available in 1.67 plastic. The suggested minimum fitting height is 18 mm.
What's new in PALs
(Editor's note: Information on the new Gradal Individual and Gradal Short i by Carl Zeiss Optical, which was unavailable at the time this feature was written, appears in
"Pulse" on page 14.)
Definity, by the Spectacle Lens Group, a Johnson & Johnson Vision Care Group company, is the first-ever dual surface add design. What makes this product unique is the proprietary use of different progressive designs that are placed on the front and back surface of each lens. This may assist the clinician in achieving a more comfortable PAL.
The lens designer has twice the surface area to distribute unwanted astigmatism; it's distributed in different patterns over both surfaces. By offsetting the peaks of astigmatism on the front and back surfaces, some cancellation of unwanted astigmatism occurs, reducing peripheral distortion and widening the intermediate channel. This also results in a "soft design."
Another feature of this product is what the manufacturer terms the "fourth zone:" If the lens is fit with a seg height of
23 mm or more, there's a reduction of 0.12D to 0.75D below the reading area. This drop in power decreases pincushion distortion so that stairs and curbs appear less curved or distorted.
Increasing add power in PALs results in an increase in peripheral unwanted astigmatism (Remember the 1:1 rule). Because of its dual surface add design, increasing the add power with Definity lenses results in a decrease in unwanted astigmatism in comparison with traditional single-surface PAL designs. This results in a wider intermediate zone, a tremendous benefit to patients when we must increase their add power. If a patient requires a +2.50 add, it exhibits the reduced distortion of a +1.75 add in a single-surface progressive. Our practice has had tremendous success with this lens in patients who spend most of their day at a computer terminal.
This product is available in polycarbonate, CR-39 and Transitions CR-39 and 1.60 High-Index materials. It's currently only available with
Gemcoat, the company's anti-reflection system.
You must remember this
It's imperative that the practitioner and optical staff be familiar with the different designs of each of the PALs they offer in their dispensary. The importance of accurate measurements in fitting these lenses can't be overstated. Pre-adjust the frame before taking measurements to ensure the accuracy of segment height measurements on every patient.
Determine segment height while taking into consideration the patients' requirements at their workplace and their natural head and body posture. Take monocular pupillary distances (PD) to align the optical center of the lens. These measurements should be taken only with a monocular
pupillometer. If the PD isn't accurate, the patient will never be satisfied regardless of the PAL design, as their eyes won't be able to track along the progressive corridor into the near segment.
We always schedule a two-week follow up with our optical manager that we term a "spectacle progress evaluation" after dispensing a progressive lens, regardless of how long a patient has been wearing a progressive lens. This visit emphasizes the technical nature of the lens design and assures the patient continuity of care between the clinical and optical aspect of our practice.
Dr. Rosenblatt is president of Rosenblatt Family Eyecare Associates in Raritan, N.J. Contact him at (908) 725-3331 or
Optometric Management, Issue: September 2003