Lenses: The Big Picture

An OLA-sponsored article on avoiding some common dispensing pitfalls

By Alex Yoho, ABOM

The most beautiful and stylish frame can become an ugly duckling when the wrong lenses are used. In this OLA-sponsored article, we will investigate some of the common pitfalls to avoid.

Thanks to the following lab folks for contributing their thoughts: Drake McLean, president, Dietz-McLean Optical, San Antonio, Texas; John Granby, president, Deschutes Optical, Boise, Idaho, and Bend, Ore.; Ray Knoll, vice president, Northwest Region, Hoya Vision Care, Seattle; Jacquie Honstrom, production manager, Next Generation Ophthalmics, Inc., Grand Rapids, Minn.; Don Hampton, lab manager, Diversified Ophthalmics, Inc., Cincinnati; Kim Scheidler, director of education, Sutherlin Optical, Kansas City, Mo.; Karen Stotz ABOC, NCLC, quality assurance/internal education, Pech Optical Corp, Sioux City, Iowa.

BASIC ECP ERRORS

Q What are the basic mistakes most often made when ECPs recommend frame-lens combinations?

McLean: Not pre-adjusting the frame prior to taking measurements.

Honstrom: Rimless frames in high Rx patients. Not spending extra for rolled edge, or a polish on rimless.

Knoll: Selecting the frame first. It is always best to select the lens design first, based on the prescription, then the frame based on cosmetic and lens considerations, and, finally, lens material.

Granby: Ordering lens styles that aren't available in the material they want, or, a material that isn't practical for the frame.

Hampton: Base curve and frame base are overlooked, often compromising the shape and ultimate fit of the frame.

Material should always be part of the decision when choosing certain frames to eliminate chipping or cracking. With the extended offering of short corridor PALs, they are not always selected for short B measurements.

RIMLESS ADVICE

Q What advice would you give when using rimless drill mounts?

Knoll: Use the optimum material for the patient's Rx, based on cosmetic considerations. Also, minimizing the size of the lenses will often make a significant difference in thickness.

Granby: 1.60 high index lenses have the best selection of lens styles and 1.60 is very durable for drills. Keep the difference between the frame PD and patient's PD less than 8mm, and you have the best chance for the thinnest lenses.

Honstrom: High index material, AR coating, depending on the color of the frame, possibly edge painting, or polish the edges. It doesn't have to be a shiny polish.

Hampton: Be very mindful of power restraints and always select the appropriate material—Trivex or 1.60 are good options.

Scheidler: A frame that adjusts perfectly with demo lenses may not fit the patient's nose at all after adding the Rx. If you're unsure how thick the lens will be, call your lab. We can usually tell you how thick the lenses will be and how much thinner or thicker they'll be with a different material or different size.

Stotz: It is also necessary to have an understanding of the Rx restrictions related to the mounting hardware.

UNDERSTANDING WRAPS

Q Why have wrapped lenses been frustrating?

McLean: General lack of understanding of Rx recalculation.

Granby: Patients with Rx powers over -2.50 should be given a first and second choice frame. Send both frames to the lab for evaluation and let the patient know that if one frame won't work, the other may.

Also, make sure your lab figures magnification difference, between a conventional frame and wrap frame, to ensure the patient can adapt to the curve change in a wrap.

Knoll: Until recently, tracers and edgers were not designed to handle high-base frames or lenses. Newer equipment is now available to overcome these limitations, and cosmetically pleasing lenses can generally now be produced, though still with some limitations.

Honstrom: Dispensers order the job and don't tell the lab ahead of time that it's a wrap frame. If lenses were made for a normal frame, we have to start over.

Hampton: There seems to be a lack of understanding of constraints in parameters. PD, power, bevel, and eye-wire correlation all play a critical part as to whether or not there can be success with a wrap order.

Stotz: Perhaps the most frustrating part of wrap lenses is the limited usage areas offered by many manufacturers. However, optimization has helped increase patient success rates on wrap lenses.

PATIENT RECOMMENDATIONS

Q What do dispensers need to watch out for when making recommendations to patients?

McLean: Power in each meridian and how that impacts thickness, PD, and total decentration. Having adequate lens area for maximum vision, minimum fitting heights, and distance window are often not considered.

Honstrom: Dispensers need to make sure that the recommendations meet all parts of their lifestyles if the patient isn't going to buy multiple pairs.

Scheidler: Be careful what and how you say things. Patients hear absolutes!

"I'll try to have them Friday" is often heard as "On my sainted mother's grave, they'll be here Friday for sure, if not Thursday!"

PROCESSING FAILURES

Q What are some examples of sure-fire processing failures?

Granby: Ordering things that are just not possible, such as round segs in poly, Transitions ST-7×28 in poly, drilled rimless in plastic, conventional PAL at a 15 seg height, and over-the-counter frames of poor quality used for Rx lenses.

Knoll: Combining steep curve lenses with low curve frames, or vice versa, particularly if the frame is constructed of anodized aluminum (this will likely result in frame damage); attempting to combine a drill-mount frame with too-thick lenses, resulting in a job that is cosmetically unacceptable, sometimes so difficult as to result repeated fabrication attempts and long delays; ordering thin-edge lenses or an inappropriate lens material in a metal-groove frame.

Hampton: Poor PAL selection for a small frame.

Scheidler: Plastic, or some mid-index lenses in drilled rimless or the grooved metal and plastic frames.

Stotz: Pushing the limits of what is advised by the manufacturer.

VISUAL ACUITY

Q What can a dispenser avoid that might create visual acuity failures?

McLean: Note the difference between an old Rx and new.

Granby: Avoid poly over +/-4.00, spherical lens designs with powers over +3.00, and specifying too thin of a center for the material request.

Knoll: Provide the fitting height when ordering aspheric single vision lenses. In the case of aspheric lenses, the surface is produced to accommodate for off-axis viewing, but if the OC is not located properly, the patient will never be using the lens as the designer intended.

Honstrom: High-minus patients in a high wrap frame.

Hampton: Improper use of higher indexes, especially in lower powers that can induce ghost images.

Scheidler: Tints that are too dark, even in sunwear. The darker the lens, the more the eyes dilate.

When asked who is in the best position to avoid any problems with eyewear, all our panelists responded: the well-trained dispenser.

Remember, your patients come to you excited about the prospect of getting that cool new frame, but, if we tackle the lens aspect first, designing that perfect pair of eyewear will really come together. If these concepts are foreign to you, take the time to work with your lab to gain a good understanding of what it takes to make beautiful lenses that won't spoil the appearance of the frame. EB

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