Guidelines for Selecting Clinical Loupes

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ErgoPractice News – August 2016

Are you or someone you know at risk of a career-ending neck injury?

The August 2016 Independent Clinicians Report has a cover story titled “Clinical Guidelines for Selecting Loupes.”1 This report contains a survey with answers to several important questions about declination angle vs head tilt angle, features of fixed Through-The-Lens (TTL) loupes, and Flip-up Front-Lens-Mounted (FLM) loupes, the effect of working distance on images and/or vision, and more.

The CR survey of 1600 clinicians found several interesting facts:

  • Over 90% of dentists surveyed are using loupes
  • 76% of them are using fixed TTL loupes and 20% flip-up FLM loupes
  • Nearly 90% of loupe wearers rated loupe ergonomics as either very or extremely important
  • Many experts recommend declinations angles larger than 35 degrees and head tilt less than 25 degrees

The Clinicians Report concludes “Clinicians are trending toward ergonomic loupes with longer working distances, higher magnification, and greater declination angles. Longer working distances facilitate better posture and a neutral working position; however, images will appear smaller unless magnification is also increased. Reduce neck and back strain with greater declination angles.”

Although nearly 90% loupe wearers consider loupe ergonomics as one of the important factors in selecting loupes,1 we find many of the loupes sold with the label “ergonomic loupes” do not meet ergonomic requirements. These loupes force wearers to tilt their heads much more than 25 degrees forward (Figure 1). Some companies use the angle between the axis of loupes and temple arms as the declination angle, but the accurate declination angle is the angle between the axis of loupes and the line connecting the top of ears of wearers and the corner of eyes.2

What SurgiTel can do for you: SurgiTel as a Division of General Scientific Corporation was established to provide clinicians with ergonomically correct loupes. During the last 25 years, SurgiTel has introduced ergonomic FLM loupes with patented loupes mounts which allow users to create their optimum declination angles. With patented frame designs SurgiTel is able to offer ergonomic TTL loupes with steep declination angles. Also, SurgiTel has provided clinicians with free ergonomic consultations. We can help evaluate your working postures with your current loupes. With switching to SurgiTel’s ergonomic loupes many clinicians have eliminated or significantly alleviated their chronic neck pain which was developed with the use of traditional loupes.2,3

How Can We Find if We Have Non-Ergonomic Loupes?

First, listen to what your body is telling you. If you feel frequent neck pain chances are your loupes are forcing you to excessively tilt your head more than 25 degrees forward (Figure 1).

Pain is our body’s way of telling us “I don’t like what’s happening!” It is our internal alarm system. Be sure to listen. Too many tell themselves “I’ll take care of it soon” or, even worse, “it’s just the cost of doing surgery/dentistry.”

Daily comfort and long term safety not only enhance the length of your career but also the quality of your work. Can you really give your patient all your attention when you are also feeling debilitating neck pain and/or back pain? Working ergonomically is not only a benefit to the clinician but also to the patient.

You can easily find that your loupes are non-ergonomic loupes by finding your head tilt angle. You can find your head tilt angle by taking two posture photos and comparing them.4 The first one is a photo for the neutral posture of your head and the second one is a photo for the posture of your head which you try to see the operating site through your loupes. Comparing these two photos you can easily find your head tilt angle. Remember: the past 25 degrees forward is in the danger zone!1

How Can I Get Ergonomic Loupes?

If you have neck pain, or if you have checked your posture wearing loupes and found that your loupes do not meet the requirements suggested by Clinicians Report,1 you should look into replacing your loupes immediately. Do not plan on doing it later. This is too important to get lost in the shuffle and get put off for a year! Below are some important points to consider when selecting/upgrading loupes:

Ordering and Checking a Steep Declination Angle

When you order your new loupes, let your local representative take a side view photo of you wearing the demonstration model looking at the operating site through the loupe. You may want to see yourself with a more upright posture, looking download at a steeper angle.

When you receive your loupes, you should be sure to take another side view photograph and measure your head tilt.2 No matter what, be sure your head tilt is no greater than 25 degrees.

Even if your head tilt is less than 25 degrees, it should be noted that some manufacturers achieve a steep declination angle by compromising the loupe’s vertical position. The vertical position of loupes is a very important measurement that is used to place the ocular at an optimum location between your eye and your target. Both correct positionings of loupes and steep angles is imperative to achieve the best image quality and the safe head tilt.

See Figure 2 for a comparison between a steep declination on a traditionally designed frame (2a) and a steep declination angle on a next-generation ergonomic frame (2b). You can see that steep declination angles of TTL loupes are achievable with traditional frames, but the line of sight is not co-axial to the axis of loupes. Ergonomic TTL loupes with steep declination angles require specially designed frames.

With FLM loupes, declination angles can be more flexible. But only FLM loupes with vertically adjustable loupes can offer true adjustable, ergonomic declination angles while also keeping the loupes in line with your eye. FLM loupes without vertical adjustability can cause the same issue as demonstrated in Figure 2a.

In figure 2a, where a steep declination angle is achieved, but at the cost of a co-axial alignment to the eye line, the image quality is reduced, shadowing can occur, and as demonstrated in the pencil diagram – tools moving into the magnified field will be misaligned with magnified images and difficult to use.

Measuring the Declination Angle

To compare the effective declination angle of loupes mounted onto different frames we must measure the declination angle of loupes using an invariable reference line connecting the bottom of temple arms above the ears of the wearer to the corner of eyes.

But some have used temple arms as the reference line (as in Figure 3a).5 If we use temple arms as the reference line for the measurement of declination angles, the declination angle measurement will vary as the position of temple arms connected to lens frames varies. If temple arms are connected onto the top edge of lens frames, the declination angle measurement will become larger even if the downward angle of loupes stays the same. The measurement of a loupe’s declination angle without the user will not be accurate.

So to correctly compare the effective declination angle of loupes, even those on totally different frame designs, you must measure between the axis of loupes and an imaginary line between where the ear connects to the face and the corner of the eye (as in Figure 3b). With this measurement, no matter the design of the temple arm, the effective declination angle which actually describes the user experience can be measured.

The declination of loupes also depends upon your facial features, such as nose height. The best way to find ergonomic loupes may be to simply measure your head tilt angle while looking through the loupes at a target.

Working Distance and Magnification Requirements

The Clinicians Report notes changing to a longer working distance facilitates better posture. They also note that with this increased working distance – images will appear smaller unless magnification is also increased.
How does this affect work?

The distance to our target will affect our vision. Imagine you are on a street with two cars in front of you (Figure. 4). One is closer and one is farther away. You can read the closest license plate but you cannot read the farthest. In order to see better, you need magnification.

Whether by a telescope, binoculars, or loupes – magnification makes the object appear closer so you can perceive more detail. Using magnification you may be able to see the farther license plate as well as you could see the closest without magnification.

In the same way, a longer or shorter distance from the license plates affects perceived detail, a longer or shorter working distance affects perceived detail through loupes.6

For a clinician with a shorter working distance, as if they were standing closer to the cars, they will perceive greater detail. For a clinician with a longer working distance, as if they were standing farther from the cars, they will need a greater magnification to see the same level of detail.

In the same way, two clinicians with different working distances will experience different magnification effects, so does a single clinician when they change their working distance.

I have worked with many clinicians who upgraded their loupes to achieve better ergonomics. Many would work hunched over and leaning in at a shorter working distance, 14 inches for example. They order new ergonomic loupes to work in a new upright posture and are now at, for example, an 18 inch (or longer) working distance. They notice that the magnification effect is decreased and feel cheated. Some of them return their loupes outright. I am glad Clinicians Report has brought light to this issue. It is very important for clinicians to consider the distance effect if they are changing their posture and ordering magnification.

If you are purchasing new loupes with increased working distance, please be sure to increase your magnification as well!

Contact SurgiTel

If your posture evaluation shows a potential posture issue, don’t wait until you feel pain. And if you are in pain, don’t just accept it or put it off finding a solution. Contact your local representative at SurgiTel.com/MyRep to schedule an in-office demonstration right away!

 


References:
  1. “Clinical Guidelines for Selecting Loupes.” Clinicians Report Aug. 2016: 1-2. Print.
  2. Darryl L Hatchett, SurgiTel Delivered the Magnification I Wanted Without the Pain, ErgoPractice News, June 2014. https://surgitel.com/testimonial-darryl-l-hatchett-dds/
  3. Amjad Ansari, SurgiTel’s Ergonomic Loupes Freed me from Neck Pain, ErgoPractice News, Feb 2015. https://surgitel.com/testimonial-amjad-ansari-bds/
  4. Chang, B., Ph.D. (2014, July 01). Declination Angle: The Key Factor for Custom Loupes. Oral Health. https://www.oralhealthgroup.com/features/declination-angle-the-key-factor-for-custom-loupes-b-j-chang-phd/
  5. Osuna, Tricia. “A Checklist For Shopping For Loupes”. 2016: 28-30, 32. Web. 29 Aug. 2016.
  6. Chang, BJ, How to Determine Your Custom Magnification Needs, ErgoPractice News, September 2013. https://surgitel.com/how-to-determine-your-custom-magnification-needs/