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The Connection Between Ergonomic Loupes & Head Tilt

ErgoPractice News – April 2017
By Jin Chang PhD

Including a Conclusive Technique to Know if Your Head Tilt Is in a Safe Range

In order to have a long and healthy career, free of pain and injury, we need to work in a neutral posture. We may move through all sorts of postures, but the sustained posture needs to be neutral. If not stress and strain will add up to damage, which can lead to a career-ending injury.

Why a Neutral Posture?

Our bodies are supported by our muscular and skeletal structures. These systems do a wonderful job of holding and moving our bodies. The spine structure has several natural curves creating a smooth S-shape. This shape distributes the mechanical stress incurred as our bodies are both at rest and in movement.1

Before loupes were popularized, clinicians would lean far over their patients to get a better view of their work. This created a C-shape in their spine, since they leaned in from their waist and hovered over their target. Working in this contorted position caused clinicians dangerous lower back problems. Then loupes changed the game.

What Causes Neck Pain?

Custom loupes with a proper working distance can eliminate lower back pain. But if the loupes do not have a proper declination angle, the loupes can actually cause neck pain.2 It should be noted that many custom loupes do not have a proper declination angle. In these cases, the pain has only been moved from the lower back to the neck.

If the declination angle of the oculars is not steep enough (Figure 1a) the clinician is bending their neck at an extreme angle to compensate. Holding the head in this unnatural position causes stress and strain in the muscles and spine. This causes pain and eventually, it may cause career-ending injury.

Properly made, truly ergonomic loupes (Figure 1b) allow the clinicians’ eyes to look down without bending their neck beyond a safe range. This neutral position allows clinicians to work comfortably and safely and have a long career free of pain.

When is Ergonomics a Buzzword?

The good news is the topic of ergonomics has become more popular then ever over the last few years. It is being discussed at trade events, it is being taught in resident and student programs, and articles are being written about it in many different magazines.

The bad news is many get all sorts of ergonomic information wrong. Even in peer-reviewed printed articles, we have seen the gamut from small errors and mistakes to completely nonsensical statements. Some of these magazine articles even reference my own written works, but I cannot recognize their interpretation!

Even worse then mistakes are how many companies purposefully manufacture misinformation about ergonomics. This runs the gamut from using the word “ergonomic” as a buzzword to describe just about any product, to purposely inventing some convoluted story to obscure the truth.

How Can We Know What Is Truly Ergonomic?

If incorrect information is given to us at every turn, even in peer-reviewed articles, how can we know if we are working ergonomically? One signal is pain. Yet, this is not conclusive as the pain may be on the way, or may arrive after the injury is irreversible! (As always, please share these articles with anyone you know in pain, as they are working like Figure 1a!)

In the past we have tried to help clinicians find their declination angle, to help them understand if their loupes meet their requirements. However, we have found this difficult to measure. And even worse is how several companies are claiming their products are ergonomic by measuring declination angle with temple arms. If the temple arm is mounted at the top of the eyeglasses, the declination angle is falsely inflated. In Figure 2 this trick almost doubles the declination they claim.

Because of this confusion, we now recommend you forgo measuring your loupes and simply measure your posture. Why measure the tool if you can directly measure the tool’s effect?

How Can I Measure Head Tilt?

Because your eye line to your target is made up of your neck tilt plus the declination angle of your loupes, increasing your declination angle reduces your neck tilt by the same amount.

To get a good approximation of your head tilt, have someone take a picture of you from the side sitting in an upright posture, with your back parallel to the wall, and holding your head upright. Then take another photo with your back parallel to the wall and tilting your head to look at a target through your loupes (Figure 1).5 The difference in head tilt should not be more than 20-degrees. We can measure your head tilt for you. You may e-mail me at

Remember, if your neck tilt is less than 20-degrees,3 you are in the safe range. If your neck tilt is greater than 20-degrees, then you may be on your way to pain and injury.4

Please share this conclusive technique!

Ergonomics is more popular than ever, but there is also more confusion and misinformation than ever. If you suspect any of your coworkers or peers are in pain, or are on their way to pain and injury, please share this article with them.

Only by crowding out the misinformation can we halt this decades-old pain neck pain epidemic!



  1. Eidelson, Stewart G., MD. “Normal Curves of Your Spine.” SpineUniverse. February 14, 2014. Accessed April 27, 2017.
  2. Rucker LM, Surgical telescopes: posture maker or posture breaker? In, Murphy D, ed, Ergonomics and the dental care worker. Am Public Health Assoc, Washington DC, 1998, 191-216
  3. Valachi B, Practice dentistry pain-free, Posturedontics Press, Portland, OR, 2008,
  4. Chang BJ, Ergonomic benefits of surgical telescopes: selection guidelines, J Cal Dental Assoc, Vol.30.No2., 2002: 161-169
  5. Chang B.J. Declination angle: the key factor for custom loupes. Available at Accessed April 24, 2017.