Developing a List of Requirements for the Ultimate Loupes and Their Hidden Costs

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ErgoPractice News – January 2022
By Jin Chang PhD
jchang@surgitel.com

Summary

Our goal as a company is to design, engineer, and build the Ultimate Loupes. We would like to develop a list of requirements as a guide and criteria for building the ultimate loupes. Once we establish a list of essential requirements for these ultimate loupes, we would like to invite clinicians and institutes to evaluate various brand loupes against these established requirements to help clinicians make wise decisions in purchasing their loupes for their clinical applications. Please review the requirements which we have identified below, and let us know if you or your institute is interested in evaluating various loupes or if you are willing to share your experience with loupes that do not meet these essential requirements. If your story is selected as a testimonial, we will recognize you as an educator by sending an educator plaque and a prize.

A Brief History of Clinical Loupes

Loupes were originally designed to help visually impaired people read fine print. Then, surgeons started to use loupes for their microsurgical procedures. Later in the early 1980s, dental professionals started to use loupe for their practice. Today, loupes have become an essential instrument for the practice of dentistry and surgery. The initial objective of using loupes was to help users see better, and then loupes were promoted to help users work with improved postures. Unfortunately, many loupes used by clinicians today are still forcing them to excessively tilt their heads, creating chronic neck pain or injury. Poor ergonomic loupes are the leading cause of chronic neck pain among dentists and surgeons.

Why Establish Requirements for Ultimate Loupes?

Many clinicians, particularly students, may purchase their first loupes based on prices, claims (often not true) made by sales reps, frame color, or latest style. However, there are significant hidden costs such as medical treatment of pain or injuries developed due to the use of non-ergonomic loupes, loss of working hours, early retirement, and cost for updating prescriptions. Also, there are many other issues related to improperly assembled loupes such as misalignments of optics, poor fitting, eyelashes touching optics, and fogging. The list of established requirements for the ultimate loupes will help clinicians make wise decisions in purchasing their loupes.

Proposed Requirements of Ultimate Loupes and Hidden Cost

Basic requirements of ultimate loupes we identified can be divided into three categories: vision, ergonomics, and other requirements as follows. If you think of a requirement that should be added, please let us know.

  1. Vision Related Requirements
    1. Minimum magnification requirement: If the working distance is less than 15 inches (or 38 cm) which was the average working distance of dental professionals in the past, 2.5x is adequate as a beginner pair of loupes. As clinicians have started to work more upright with better ergonomics, today the average working distance of dental professionals and surgeons is longer than 18 inches. New generation clinicians should use at least 3.0x loupes as their starting pair of loupes.1 Figure 1 shows the distance effect.
      Hidden cost: If you choose loupes with inadequate magnification power, you can make the wrong clinical decisions by missing details.

    1. Wide field of view: The field of view of Galilean loupes becomes smaller as the magnification power increases. Keplerian (or prism) loupes offer a larger field of view, but because of the extra glass and assembly, they are more expensive than Galilean loupes.
      Hidden cost: Wider field may help, but there may not be any serious hidden cost if you can see the operation site well.
    2. Custom working for each procedure: Clinicians may stand or sit for various procedures. These clinicians can have multiple pairs of loupes with different working distances, although the best option is when the clinician is able to change the working distance on the same pair of loupes.
      Hidden cost: If one pair of loupes cannot offer multiple working distances, you have to purchase multiple loupes. If loupes can have multiple working distances, you do not need additional pairs of loupes.
    3. Precision alignment of two oculars in the vertical direction requires sturdy frames for Through-The-Lens (TTL) loupes and stabilized ocular mounting arms for Front-Lens-Mounted (FLM) loupes.
      Hidden cost: If this alignment is not accurate, this misalignment can create double images in the vertical direction and can cause eye fatigue, as well as headaches.
    4. Precision alignment of oculars to eyes requires accurate measurement of custom data and advanced manufacturing methods. It may be desirable that users can make fine adjustments with custom nose pads. This alignment can be tested by bringing a pencil into the magnified field. If the alignment is precise, the pencil and image of the pencil should be aligned.
      Hidden cost: If direct vision and magnified vision are not precisely aligned, the image quality becomes poor. If the misalignment is too large, handling instruments may be difficult.

  1. Ergonomics Related Requirements
    1. Safe head tilt angle (neck posture): The head tilt angle should be 20-degrees to prevent chronic neck pain or injuries.2,3 We can easily measure the head tilt angle with two side view photos (side view photo of neutral neck posture and side view photo of working posture wearing loupes (Figure 2). Custom declination angle of loupes is required for each customer to ensure a safe neck posture. Note: A backward head tilt is not desirable.
      Hidden cost: The use of non-ergonomic loupes for an extended period may create chronic neck pain. Once the chronic neck pain is developed, there may be significant financial costs (loss of practice time, medical treatment, an early retirement). 4,5

    1. Ergonomic declination of eyes: The comfortable declination angle of eyes may be between 5 and 35-degrees. The declination angle range of eyes is between 0 and 50-degrees. Ideal loupes should allow eyes to decline more than 5-degrees.
      Hidden cost: If the declination of eyes may be outside of the comfortable range, eyes can be strained.
    2. Custom nose pads: The single type of nose pad cannot fit all nose types. Custom nose pads should allow users to wear comfortably and eliminate eyelashes touching oculars, fogging, and blocking direct vision.
      Hidden cost: Poor fitting and uncomfortable to wear.
  1. Other Requirements
    1. Easy restoration of the increased working distance of TTL loupes due to the change of reading prescription is desirable.
      Hidden cost: If users cannot restore the working distance, manufacturers should update the prescription – Updating the prescription will not only take several weeks but will also  be very expensive (several thousands of dollars over the lifetime of the loupes and the need of a back up pair of loupes, double the cost if you have a second pair of loupe, backup of different magnification).
    2. Short learning time is desirable.
      Hidden cost: If learning is not easy, we have to make investment in earning and low productivity.

Evaluation of Your Loupes

We invite you to participate in evaluating your loupes with established requirements of ultimate loupes and to share your evaluation with our readers. Once the list of requirements is finalized, we will email the list with evaluation methods. We will give awards to clinicians whose evaluations are selected for publication.

 

References

  1. Chang, Jin. “Choosing Loupes for Dental School: Three Most Common Myths in the Loupe Industry Demystified.” SurgiTel. ErgoPractice News, July 2018. https://www.surgitel.com/choosing-loupes-for-dental-school-3-most-common-myths-in-the-loupe-industry-demystified.
  2. Chaffin, Don B. “Localized Muscle Fatigue – Definition and Measurement.” Journal of Occupational and Environmental Medicine 15, no. 4 (April 1973): 346–54. https://journals.lww.com/joem/Citation/1973/15040/Localized_Muscle_Fatigue___Definition_and.4.aspx.
  3. Valachi, Bethany. “3 Keys to Eliminating Neck Pain in Dentistry.” Posturedontics. Posturedontics, n.d. https://posturedontics.com/the-top-5-keys-to-eliminating-neck-pain-in-dentistry/.
  4. Valachi, Bethany. “WellBody System for Dental Professionals.” Posturedontics, n.d. https://posturedontics.com/wellbody-system/.
  5. Chang, Jin. “The Hidden Cost of Non-Ergonomic Loupes and Cool/Blue-Tinted LED Headlights.” SurgiTel. ErgoPractice News, March 2021. https://www.surgitel.com/the-hidden-cost-of-non-ergonomic-loupes-and-cool-blue-tinted-led-headlights.