Features: Special Section

May
2004

Spec-ulating


By Palmer R. Cook, OD

Most people associate the term eyewear design with fashion. But there is another type of eyewear design that takes place not in the design studio, but in the dispensary. Today’s ophthalmic technology allows the “Specs Experts” to design attractive, comfortable, high-performance eyewear for every patient.

Great “specs experts” recognize that the prescription is just the foundation for patient pleasing eyewear. They know their frames and they take note of their patient’s facial anatomy, complexion and preference of style as they are discussing lens design. Often these experts can reach up and pull an ideal frame from their display in a matter of moments. This is no trick.

Experienced optical dispensers develop an almost uncanny ability to pick a great looking, great fitting frame for a patient almost at the blink of an eye. The beauty of this ability is that there is a very human bias for returning to the first tried-on frame as the first chosen. A great choice right off the bat will frequently be the choice the patient returns to—the best and final choice.

The shape of the eyewire is usually the primary focus of frame selection. A dark, round front on a patient with a round face, arched eyebrows, big round eyes and a curved, arching hairline creates a dramatic design—which might work great if your patient was Humpty Dumpty. Selecting a rimless frame with round lenses, an arched bridge and delicate temples for the same patient would be a blended design, which is usually done to make the eyewear as unobtrusive as possible. A more rectangular shape, with some arch to the top of the eyewire to better parallel the brows and a frame color that complements the patient’s complexion and hair color would make this a balanced design. For most patients a balanced design is most appropriate.

Another key aspect of frame selection is the position of the temple attachments—at the top of the eyewire, at the bottom of the eyewire or somewhere in between. High temple attachment swings the bottoms of the lenses closer to the eyes when pantoscopic angle is added. This effectively widens the reading area for PAL wearers. It can cause the bottom of the eyewire to ride on the cheeks, especially when the patient smiles. A low temple attachment swings the tops of the lenses away from the eyes. This allows more lash relief, which can be important with today’s flatter, aspheric curves. It also can reduce the problem of “brow smudging.” Temple attachments between the extremes of “at the bottom” and “at the top” affect the position of both the tops and bottoms of the lenses.

The position of the bridge can significantly affect the patient’s appearance. Bridge attachments at the top of the eyewire make the apparent length of the patient’s nose longer and lower bridge attachments shorten the nose. Lower bridge attachments also tend to make the frame more ornate or busy because the bridge does not blend in with the tops of the eyewires. A low bridge can be cosmetically helpful with wide PDs and just the opposite with narrow PDs and tightly bunched facial features.

Also quickly make needed bends or do a little realignment of the pads before the patient puts the frame on.

The Prescription
Most ophthalmic prescriptions only give the light bending properties that the patients require and the interpupillary measurement. For many prescriptions the lens design is so interdependent with the frame design that optimal lens material choices and other lens parameters can’t be made in the exam room. Nevertheless every doctor should assume the responsibility of discussing basic lens and frame options whenever a lens Rx is written. You are pretty much left to your own devices for lens curvatures, absorptive properties, index, Abbe, specific gravity, break resistance, MRP positions and other eyewear design properties.

The Patient
Patients have anatomic differences, differences in goals, occupations and avocations. They also vary in mindset, attitude and experience level, and they fall across a wide range of ability to understand and communicate. Even worse, although they look to the doctor to give advice on what they should have, when they sit down with you at the frame bar, they feel they are now in a situation in which you are going to “sell them a pair of glasses.” In their minds you are a sales person. This alone is a good reason for establishing your expertise and professionalism by beginning with the lens discussion rather than the frame selection.

The absolute best way to share the mantle of trust that exists between the doctor and patient is for the doctor to tell the patient in broad terms about their eyewear needs and then for the doctor to introduce the patient to you. Barring this, a second best alternative is to be able to honestly say to the patient, “The doctor says for this kind of prescription you should have…” Any doctor for whom you routinely fill prescriptions should be willing to have a discussion with you on what he expects in terms of eyewear for his patients.

As you finalize the look, get at least an approximate alignment of the frame you are going to use. Then ask for a big grin. If the patient’s cheeks do a bump and grind on the bottom of the frame, you can re-align or re-select the frame.

Patient Challenges
Meet Charley and Tom, patients whom most of you are probably familiar with. Both offer a lot of opportunity for using today’s great ophthalmic technology. The most important point is that you need to be an eyewear expert, with perhaps a little bit of Sherlock Homes thrown in, rather than simply an ophthalmic pharmacist who just fills a prescription. Your efforts will help make patients see better, look better, be more comfortable and even perceive a higher value in their own eyewear. Your reward will be happier patients, a more productive dispensary and a much more interesting workday.

Chubby Cheeks Charley
Rx: OD -3.00 = -2.75 x 180,
OS -3.25 = -3.00 x 180 with no add. Charley, a physically big guy, is a blond haired, blue-eyed extrovert. He works in sales and spends hours on the freeways covering a three-state territory in the Midwest. His favorite sport is basketball. His facial shape is round, reminiscent of a basketball, and his maximum facial width is 160mm. His distance PD is 66mm.
Thoughts & Suggestions
Charley’s eyes, nose and mouth occupy an island in the center of his face. A lot of detail around his eyes will not improve his appearance. Use a simple, blended design. Charley has only about 3 diopters of minus in the horizontal meridian, but he has -5.75 OD and over -6.00 OS in the vertical meridians. A big B measurement on Charley will increase the bottom (and top) edge thickness. This could be a problem as his “chubby cheeks” would bump on the lenses when he smiles. The problem will be even worse if you place his distance MRP high in the eyewire. His round, short face would not do well with a large B measurement from a cosmetic standpoint either. On the other hand, a very small B measurement could look ridiculous on a man of his stature. A 50-20 choice would have the frame PD just 4mm greater than the anatomical PD, but the eyewear’s boxed width (2 x A + dbl) would only be 120mm which could look odd on a face that is more than 160mm in width.

Turnback temples that exaggerate the frame width might help. If a large A measurement is used, edge thickness will be increased and overall weight will go up (Caution: patients with blond complexions tend to be more pressure sensitive). Charley is doing lots of driving so polarized lenses to minimize veiling glare from the windshield should be recommended. Anti-reflective lenses for night driving and to facilitate good eye contact with his customers should also be discussed. AR lenses will also be helpful with the high, bright lighting in gymnasiums.

Both a roll and polish of the lens edges and a higher index material will reduce the edge thickness at the bottom of the lens and give Charley some “cheek relief” when he smiles. Consider using a zyl frame with an especially wide eyewire laterally. This is the equivalent of using turnback temples in a wire frame. One advantage of a zyl design is it can cover up those wooly eyebrows. Don’t forget to discuss sports eyewear.

Long Nose Tom
Rx: OD +7.50 = -0.50 x 045, OS +6.75 = -0.75 x 180 with a +2.25 add. Tom has a craggy rectangular face with a long, prominent nose and bushy eyebrows. He is an accountant and his hobby is reading medieval literature. His vertex distance is 21mm. His facial width is 130mm and his distance PD is OD 37, OS 33. His two-year-old eyewear is held together with duct tape and a small safety pin is substituting for a missing left hinge screw. His previous Rx was about the same for distance, but his add was only +1.50 (in a D-35).

Thoughts & Suggestions
Tom is careless with his eyewear, so stick with a sturdy frame, and seat and seal the screws for him at the time of dispensing. He needs a balanced design that offsets his long nose and facial shape.
Minimize the length of his nose by selecting a frame with a bridge that is not at the top of the front, and, if the eyewires arc upward, they will partially disguise his bushy brows. A deep shape (big B measurement) will soften his long facial shape. Adjusting your styling frames to account for his left hyper ear will make frame selection and measurement taking faster and easier.

Tom presents some interesting optical problems. His long vertex distance will have the effect of narrowing his reading area in both D segs and in PALs. This problem is compounded by the fact that he has about +9.50 OD and about +8.37 OS at near. The magnification from this plus effectively narrows his field of view at near. A lens with a wide reading area is definitely indicated. Measure his vertex at the reading level. If it is significantly greater than the 21mm distance vertex, you may need to reduce the add to get the effective power called for by the Rx. Tom is a candidate for high index, so be sure to use AR lenses to offset the undesirable effects of the increased reflectance. Tom’s vocation and avocation make him an ideal candidate for computer/reading glasses. He will especially appreciate having intermediate power when he is at the library.

Helpful Definitions
•The “A” measurement is the horizontal dimension of a box drawn so that it just touches the top, bottom, right, and left sides of the lens.

•The “B” measurement is the vertical dimension of a box drawn so that it just touches the top, bottom, right, and left sides of the lens.

•The geometric center of a lens is found by drawing diagonals from each corner of the box that just touches the top, bottom, right, and left sides of the lens.

•The MRP (major reference point) is that point in the lens that gives the prescription. MRPs are usually placed so that the patient is looking through them as much of the time as possible.

•Decentration means that the MRP is located away from the geometric center of the eyewire.

—Palmer R. Cook, OD is director of the practice support division of Diversified Ophthalmics in Cincinnati

 

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