Photo of blocks © iStock.com/JobsonHealthcare; Frame: VANNI V1165

By Palmer R. Cook

Remember the Where’s Waldo books? That ubiquitous guy in the bright red hat and striped shirt is still challenging kids of all ages. Waldo is adroit at hiding in full view. Waldo’s there, but he is oh so hard to find.

Finding errors that creep into a lab order is a bit like dealing with those confounding Waldo pictures. Just like finding Waldo, once you spot the error, the “Oh yeah” phenomenon kicks in, and you wonder how something so apparent could have been missed.

When your lab work arrives, it should be as ordered. And most of the time it is, but occasionally there are errors or delays. Even if the lab corrects the error at no (apparent) cost, remakes are expensive in terms of patient confidence and reputation. In the long run, those remakes are paid for by wrapping the costs into the pricing of prescription work, so ultimately we all pay.
Eyewear that is incorrect is not always the result of doctor errors (those do occur), nor is it always due to blunders at the lab. Just as a pebble can start an avalanche, even minor oversights in ordering can lead to problems of memorable proportions. Eliminating ordering errors is a lot like not dropping that pebble.

CREATING THE ORDER
Someone must pull together all the data that the lab needs to fabricate the eyewear. That person is the fail-safe who can shorten delivery times, avoid remakes, make adaptation easier and improve patient satisfaction. The ordering process gives one last opportunity for “getting it right.” Inappropriate pairing of frame and Rx, selecting less-than-the-best lens material, and failing to provide accurate or even usable measurements are common mistakes that can occur during frame selection. Fortunately, many of these and similar errors can be filtered and corrected when the order is written. This serves your practice and your patients far better than allowing patients’ complaints to serve as your “first alert” that errors and omissions had occurred.

UNDERSTAND THE CHALLENGE
Step one is to be sure you can estimate the powers in the major meridians and the vertical meridians at a glance. If the meridian of strongest power falls at or near the ED meridian, edge thickness in minus lenses and center thickness in plus lenses may be problematic, and excessive decentration may create issues (Fig. 1). Imbalance in the vertical meridian is not well tolerated by many patients. Wearers of single vision prescriptions can adjust their head tilt (chin-up, chin-down) to compensate, but wearers of multifocals cannot. Even single vision wearers may have problems if the MRPs force them to assume an awkward head position. Actually, the possibilities for errors and omissions abound.

GUIDELINES THAT WORK
It may not be practical or possible to have the staff member with the most education and experience in optics writing the lab orders. A practical solution is to create ordering guidelines that screen out the critical orders. For example, it is common practice for manufacturers to give minimum fitting heights for their PAL designs. Minimum fitting heights are usually the distance from the Fitting Cross to the level of the Near Reference Point (NRP). If an order is written for a Fitting Cross height that is equal to the minimum fitting height for the design being used, at least 50 percent of the reading area of the lens will be lost. In many cases, the loss will be more than 50 percent (Fig. 1). An appropriate guideline would be to call for counsel from a senior staff member if the Fitting Cross height for each eye is not at least 2 or 3 mm greater than the manufacturer’s minimum fitting height. Another red flag is to have more than 3 mm of decentration of the distance MRP or Fitting Cross in either eye. Sometimes this decentration rule will work, other times—particularly with low power lenses—the decentration can be safely increased. For errors that occur with some regularity, see the Rogues’ Gallery of Common Ordering Errors.

HISTORY HELPS
If you know “the basics” of the patient’s previous eyewear, you have a head start. It really helps to know the base curves, tint, wrap, pantoscopic tilt, PAL design, lens material, coatings, center thickness, location of the pupillary centers relative to the pupils and vertex distance. This data gives you a lot of valuable information that should be considered when ordering new eyewear.  

BUT THE PATIENT REALLY WANTS...
The root cause for unhappy eyewear outcome is often stubborn insistence on using an inappropriate frame for either the patient’s anatomy or his prescription. If your dispensary tech caves on this one, it is the equivalent of allowing a 5-year-old to sit on your lap and steer the car. If you are the office ordering guru, you can appeal to higher authority and deflect the contentious issue by letting the patient know that “you checked with the lab and . . . ” If that doesn’t work, you can offer to let the patient purchase the frame on a non-returnable basis, and they can try to find someone who will attempt the inadvisable. Labs are plagued by the failure of professionals to simply say no when a poor outcome is inevitable. Even worse, your reputation suffers when eyewear outcomes don’t measure up.

SIGNS AND NUMBERS
Whenever writing or entering a lens power, either a minus (-) or a plus (+) sign should be used. Unfortunately, some programmers have not made provision for plus signs, assuming that no minus sign means the number is a plus value as we learned in arithmetic. If the power you want is a +1.00, the omission of the + when ordering could indicate that the sign, whatever it was, had been omitted.

When entering the axis value, three digits should always be used. This assures that you had completed the axis entry. Axis 18 could have been missing a “zero” at either beginning or end, so the meaning could have been clearly “eighteen” if it were written 018 or if written 180, “one hundred and eighty” would have clearly been indicated. When ordering spheres, close off the power by adding DS after the power. This tells everyone who sees the order that the cylinder power and axis were purposely left blank.  

WHO DUN IT

Whether it was Col. Mustard, Miss Scarlet or Professor Plum, when your lab has a need-to-know, the person who wrote the order is usually the best one to contact. Getting to the right person quickly reduces phone time for everyone. Labs want to minimize turnaround time and eliminate errors. For handwritten orders, always initial at the same place on the form, and do it only when the order is complete. The ordering initials or numeric code could go in the top line of “Special Instructions” for electronic orders.

SPECIAL INSTRUCTIONS
Special Instructions consist of information to clarify what is needed to “get it right,” which is what everyone wants. Handwritten instructions must be readable and all instructions should be clear. For example: “Patient leaving on vacation Dec. 4th” could be misinterpreted, as “We need it by Dec. 4th.” This is not going to work if the patient’s flight leaves at 7 a.m., and your lab delivery arrives at 10 a.m.

“We must dispense no later than 3 p.m. Dec. 3rd. Call at once if this is a problem,” would be a better message. Top-notch labs work hard to meet your needs, but they need the facts. If the message had omitted the “at once,” someone at the lab may decide to wait to determine if a delay could be corrected in time. An immediate lab/practice consultation would allow alternatives to be considered.

Eyewear might be overnighted to the patient’s destination, and the family could take a vacation as scheduled. Result? Problem resolved, and everyone wins.

Impossible or impractical instructions can also slow the order. A +5.00 lens cannot have a 1-mm center thickness at any sensible spectacle size, nor can a PAL be given lateral prism only in the reading area without special handling. Your lab’s customer service or consultants should be consulted before ordering when you encounter unusual Rx parameters.

THE CENTRATION CHARTS

Centration charts allow you to know whether the chosen frame will accommodate the lens measurements you have specified. Your eyewear designer (i.e., the staff member who works with the patient during frame selection) and the staff member who creates the order should each have an up-to-date notebook containing a centration chart for every design you use. Every PAL order should pass the centration chart test before the frame choice is finalized and again at the time the lab order is written. This is for the benefit of the patient (avoids frustration and disappointment), for the lab (avoids re-makes, saves time) and for the reputation of your practice (avoids embarrassment and bad word-of-mouth). Centration charts are free, and their regular use is a benefit for all.

A Rogues’ Gallery of Common Ordering Errors
  • The patient’s name is illegible or not included.
  • Special Instructions are contradictory.
  • Only one or two digits are used for the axis.
  • Power signs (plus or minus) are missing.
  • Tint is marked, but the kind and density are omitted.
  • “Frame to Follow” is marked but the frame name and color are omitted.
  • Excessive decentration is required.
  • Inappropriate edge thicknesses are specified.
  • Inappropriate center thicknesses are specified.
  • MRP heights are not given for lined or SV lenses.
  • The PD information is not included.
  • There is no identification of the person who placed the order.
  • The frame is inappropriate for the lenses.
  • The brand name is incorrectly specified.
  • The handwriting is not intelligible.
EFFECTIVE POWER
The fact that lens power varies depending on the vertex distance is well understood. Ideally, the refracting vertex and the fitting vertex should be the same. Errors creep in when these distances are unequal. Most doctors refract at about as short a vertex as they can without the lashes touching the refractor (e.g., about 12.5 to 13.5 mm). Forehead rests usually control the refracting distance. Occasionally, a patient will present with a forehead like a balcony on a Holiday Inn. In such cases, the eyewear may fit at a reasonable distance, but the refracting vertex may have been significantly longer. Lenses with approximately 5 or more diopters of power may require some compensation in powers of all major meridians. Most labs can help with this, but unless you request the compensation, it will not happen.

MAKING THE MOST OF LENS TECHNOLOGY
The best performance of any ophthalmic lens is through the optical center (OC). Doctors know that when they prescribe prism, the optical performance will decrease, so they make a judgment for every prism prescription that the benefit (usually in binocularity) will outweigh the reduction in performance. The challenge for single vision (SV) lenses and lined lenses remains, as always, to place the OC so that the patient gets the best results. This usually means that the OC, or Major Reference Point (MRP) is placed at or near the base of the pupil when the patient’s head is in the preferred position, and when the lines-of-sight are horizontal. Today, failure to specify the OC or MRP for SV is the most common ordering error in the industry, and it leads to extended adaptation periods and vague complaints about new eyewear that could easily be avoided.    

EFFECTIVE VERTICAL PRISM
Effective vertical prism can be thought of as the prism effects that the patient will have for distance viewing and for near viewing. In the past, prescribers and dispensers were generally aware of the problems of the imbalance created at near, and they specified the OCs and MRPs to eliminate the problem for distance and used slab-off (or reading glasses) to compensate for imbalance at near. ■