Ergonomics 101

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ErgoPractice News – January 2023
By Jin Chang PhD


Nearly all loupe wearers consider loupe ergonomics as one of the important factors in selecting loupes. Despite this, we find that many of the loupes sold as “ergonomic loupes” do not meet ergonomic requirements. This is why SurgiTel’s mission has been to improve the way medical, dental, and veterinary professionals work. We strive to enhance our clients’ health through providing the best products which support the best working posture and comfort, alleviating all too common neck and back strains, and helping them provide their patients with the best care. This January issue of ErgoPractice News will review basic ergonomics related to loupes so that non-ergonomic loupes can be easily identified.

Why Non-Ergonomic Loupes are Prevalent

Before we discuss why non-ergonomic loupes are accepted by many, we should first think about our natural behavior. When we look down on objects, we tend to tilt our heads rather than rotate our eyes. Ergonomic postures are a learned behavior, like an effective tennis or golf swing. You may unknowingly work with a non-ergonomic posture for many years without experiencing serious neck pain. Initially, working with non-ergonomic loupes will feel more natural than working with ergonomic loupes. Learning to work safely with ergonomic loupes is a short process, usually the adjustment period is 2 to 3 weeks, but it is very beneficial in the long term.1-4 So, we should remember that ergonomic postures are at first not a natural behavior and expect an adjustment period.

There are several reasons why non-ergonomic loupes are still accepted as ergonomic:

  1. Industry safety regulations focus on the health and comfort of patients and health care workers, but not on the professional tools clinicians use every day. These tools include their loupes, LED headlights, and seating. Unfortunately, there are no ergonomic and safety standards for these tools, so many non-ergonomic loupes have been marketed as ergonomic.
  2. Poor management of working pain created by non-ergonomic loupes. We have spoken with many clinicians who blame a bad night’s sleep or years-old sports injuries for their constant neck pain. We hear stories every day of clinicians treating their symptoms instead of examining their working posture and finding ergonomic loupes that support a comfortable and safe neck posture.
  3. Dental, medical, and veterinary professionals assume pain is part of the job. Accepting working pain as an inevitable part of working can result in permanent injury or force clinicians to leave their careers.
  4. There is a lack of information about ergonomics and misinformation. Only recently have educational programs begun to incorporate ergonomic education into their lesson plans, so there are generations of clinical professionals learning about the dangers of improperly fitted loupes only after they develop a physical problem. Working pain can take five to ten years to develop, so without proper preventative education, clinicians are at risk every day of developing debilitating working pain and injuries due to the use of non-ergonomic loupes. In response to the increased knowledge and importance placed on ergonomics, nearly every loupe company has added the word “ergonomic” to their marketing materials. Indeed, the use of loupes does allow the clinician to work farther away from their patient which reduces lower back pain, but loupes without proper viewing angles (also known as declination angles) can cause poor neck posture which leads to chronic pain and injury.

Making Sure Your Loupes are Ergonomic

Ergonomic loupes are not a “one-size fits all,” that is why SurgiTel carries three different types of ergonomic loupes: Through-The-Lens (TTL), Front-Lens-Mounted (FLM), and deflection loupes (ErgoDeflection™). You must seek ergonomically correct tools, different facial features may need different styles of loupes.

The Ergonomic Gap

The Ergonomic Gap is defined by the difference between the current working neck tilt angle and the safe neck tilt angle of less than 20-degrees.5 In order to find ergonomic gaps, you should first start by asking yourself these questions:

  • Do I hunch to improve my vision? Getting closer to objects helps us to see better, but working in hunched postures will create chronic neck and back pain.
  • Am I tilting my head too much? Do my loupes force me to excessively tilt my head? The recommended head tilt to prevent neck pain and injuries is less than 20-degrees.5 Most traditional loupes may force you to excessively tilt your head (Figure 1).

    Figure 1: Neck posture and spinal stress

  • Does my stool help me work with a neutral posture? If you sit for procedures, the selection of the right ergonomic stool is very important for neutral lower back posture support.

Three Essential Ergonomic Factors When Purchasing Loupes

Working Distance

Working distance is defined as the distance from the eyes to the work area.6 The most common problem that Dr. Bethany Valachi encounters with her clients is that the distance is often measured too short, which results in excessive neck flexion or hunching.8 Working distance should be tailored to the individual, for example, the working distance for a shorter clinician will be smaller when compared to the working distance of a very tall clinician. On average, we have found that someone who is 5′ 1″ will have a working distance of 15″, someone who is 5′ 8″ will have a working distance of 18″, and someone who is 6′ 1″ will have a working distance of 20″. A discrepancy of just a few inches can have a significant impact on your comfort and health.

Declination Angle

Declination angle is the angle that your eyes are inclined downward toward the working area. This angle should be steep enough to help you attain a comfortable working position with a minimal forward head posture of 20-degrees or less. The farther the head is positioned forward to see through the loupes, the greater the strain on the neck muscles and discs.6, 9, 10 The predominant problem that Dr. Valachi encounters regarding declination angles is insufficient, small angles that force the operator to assume an unhealthy working posture.6

To avoid this insufficient declination angle, have your local representative take a side view photo of you while you are looking at the operating site through the demo loupe when you are ordering your new loupes. You want to see yourself with a more upright posture, looking downward at a steeper angle. Even though declination angle is one of the three essential ergonomic factors when purchasing loupes, most clinicians do not know how to correctly measure it. This allows many companies to incorrectly measure the declination angle by using the angle between the axis of loupes and the temple arms. However, the true declination angle is measured between the axis of the loupes and a line connecting the top of the ear and the corner of the user’s eyes. Therefore, without a user, the true declination angle cannot be determined. Figure 2 shows how some companies use a temple arm reference line to overinflate their achieved declination angle.

Figure 2: Misrepresented declination angle claims

Frame Size/Shape

The lower that a manufacturer can place the ocular in relation to your pupil, the better the declination angle they can generally provide for you.6, 8 Note: SurgiTel has patented suspended magnification technology which secures the magnification oculars at the very bottom of a sweep or open lens type. This, along with the pantoscopic tilt of our lenses allows us to achieve a steeper declination angle than any other company. 

Ergonomic Consultants

Ergonomic consultants, some of whom are licensed physical therapists, proactively educate and objectively evaluate work environments to identify ergonomic risk factors and expose any unforeseen workplace hazards.11 Below is a list of ergonomic consultants who can analyze and improve your working posture.


Bethany Valachi –

Ergonomics Dental –


Dr. Geeta Lal –

Society of Surgical Ergonomics –


  1. Arnett, Michelle C, and Iwonka Eagle. “Impact of Loupes and Lights on Visual Acuity and Ergonomics.” Dimensions of Dental Hygiene, August 26, 2021.
  2. Hayes, Melanie J., Peter G. Osmotherly, Jane A. Taylor, Derek R. Smith, and Alan Ho. “The Effect of Loupes on Neck Pain and Disability among Dental Hygienists.” Work (Reading, Mass.) 53, no. 4 (February 15, 2016): 755–62.
  3. Sunell, S, and L Rucker. “Surgical Magnification in Dental Hygiene Practice.” International Journal of Dental Hygiene 2, no. 1 (February 2004): 26–35.
  4. Branson, B. G., K. K. Bray, C. Gadbury-Amyot, L. A. Holt, N. T. Keselyak, T. V. Mitchell, and K. B. Williams. “Effect of Magnification Lenses on Student Operator Posture.” Journal of Dental Education 68, no. 3 (March 2004): 384–89.
  5. Valachi, Bethany. Practice Dentistry Pain-Free: Evidence-Based Strategies to Prevent Pain and Extend Your Career. Portland, OR: Posturedontics Press, 2008.
  6. Valachi, Bethany. “Magnification in Dentistry: How Ergonomic Features Impact Your Health.” Dentistry Today, April 1, 2009.
  7. Hansraj, Kenneth K. “Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head.” Surgical Technology International 25 (November 2014): 277–79.
  8. Valachi, Bethany. “Neck Health: The Three Ergonomic Criteria for Loupes Selection.” Dental Economics. Endeavor Business Media, September 1, 2008.
  9. Cailliet, Rene. Neck and Arm Pain, 3rd ed., 74-75. Philadelphia, PA: F A Davis Co, 1991.
  10. Rucker, Lance M., Craig Beattie, Cathy McGregor, Susanne Sunell, and Yutaka Ito. “Declination Angle and Its Role in Selecting Surgical Telescopes.” The Journal of the American Dental Association 130, no. 7 (July 1999): 1096-1100.
  11. Koziol, Keri. “Role of the Ergonomic Consultant.” The Beacon Mutual Insurance Co., October 6, 2020.,expose%20any%20unforeseen%20workplace%20hazards.