What They Didn’t Teach You About Selecting Loupes in School!
ErgoPractice News – June 2021
Selection Guide of Loupes
When we purchase loupes, we should consider several important factors such as loupe mounting styles, magnification power, field size, declination angle, frame design, nose pad options, and maintenance cost. These factors are evaluated based on working distance, working posture (sitting or standing), and facial features such as nose shape.
Selection of Loupe-Mounting Styles
There are two basic mounting styles for ergonomic loupes: customizable FLM (front-lens-mounted) style and custom TTL (through-the-lens) loupes (Figure 1).
- If you do not know a desirable declination angle for your posture, you may choose the FLM style which allows you to try different declination angles to achieve your best neck posture.
- If you know a desirable declination angle, you may choose the TTL style, but if your nose is flat, the FLM style may be a better choice to avoid fogging and touching your eyes.
- If you are experiencing chronic neck pain, you may choose FLM loupes and adjust the declination angle gradually. Often changing the neck posture may be difficult because your neck muscles may be distorted.
Why SurgiTel? SurgiTel is the only company that can offer customizable FLM loupes and truly custom TTL loupes. You can try either FLM loupes or TTL loupes.
Figure 1: 3.5X Loupes: (A) FLM Style Loupes (B) TTL Style Loupes
Selection of Magnification Power for Your 1st Pair of Loupes
The resolution power of eyes decreases as the working distance increases (Figure #2) and thus the required magnification power increases as the working distance increases. Desirable magnification power for the 1st pair of loupes is decided based on your working distance
- If the working distance is less than 15 inches, 2.5x is a good choice.
- If the working distance is about 16 inches to 18 inches, 3.0x or 3.5x may be selected.
- If the working distance is larger than 19, 3.5x should be selected.
Many dental schools and hygiene schools recommend 2.5x loupes to their students as the 1st pair of loupes because the typical working distance of dental professionals in the past was about 14 inches, but 2.5x loupes are not adequate for students with long working distances.
Why SurgiTel? SurgiTel offers the most magnification powers with either customizable FLM loupes or truly ergonomic TTL loupes for its full range magnification (2.5x to 10x).
Figure 2: Resolution Power of Eyes VS Pupil Diameter & Working Distance
Field of View and Selection of Loupe Optics
There are two kinds of loupe optics: Galilean loupes and Keplerian (often called Prism) loupes. If you want a larger field of view with high power loupes, you should choose prism loupes which offer a larger field of view than Galilean loupes.
Why SurgiTel? SurgiTel’s patented compact prism loupes offer the largest field of view.
Declination Angle for Safe Neck Posture
Small declination angles will force clinicians to excessively tilt their heads and can create chronic neck pain as a result of using non-ergonomic loupes with small declination angle for an extended period. A safe head tilt angle is one that is less than 20 degrees¹
A B
Figure 3: Neck Postures with Surgitel’s Ergonomic Loupes (B) and Other Brand Loupes (A)
Warning: Non-ergonomic loupes support human natural behaviors, such as tilting the head to look down rather than rotating eyes downward. Young clinicians may feel comfortable with non-ergonomic loupes because they will not feel the neck pain right away. If you want to protect your neck, you should evaluate your loupes within 45 days.
Figure 4: Shows Misrepresented Declination Angle Claim.
To make sure your loupes are an ergonomic design, you should measure your head tilt angle. Using two side view photos, you can estimate your head tilt angle². If your head tilt angle is larger than 20 degrees, you should ask your loupe manufacturer to remake loupes so that your head tilt angle stays less than 20 degrees. If they cannot make ergonomic loupes, you should return the loupes. There is a significant hidden cost with non-ergonomic loupes³.
Why SurgiTel? SurgiTel can offer truly ergonomic loupes with any declination angle by using patented ergo frames and patented assembling technologies.
Frame Design and Nose Pad Options
Traditional frame designs and nose pads have not been designed for loupes. Most companies are using traditional style frames and nose pads, emphasizing styles and colors. SurgiTel invented Ergo frames which allow TTL loupes to have a large declination angle, and FLM loupes to have a large field of view. SurgiTel offers various ergo-fit nose pad options (patent-pending) which can be customized for various nose types (figure 5)
Why SurgiTel? With Ergo frames and Ergo-Fit Nose pad options, SurgiTel can offer truly ergonomic loupes to all clinicians, customizing nose pads for all nose types.
Figure 5: Examples of Nose Pad Options
Maintenance Cost
The maintenance cost of loupes includes updating prescription (Rx), repairing unbonded loupes, and restoring working distance which can eventually increase due to aging eyes. The accommodation power of eyes decreases, requiring elderly individuals to use reading glasses to read books. Once we start to use reading glasses, the reading Rx changes frequently over time and we have to update Rx. The maintenance cost of FLM loupes is the lowest because any optical shop can update eyeglass RX. The maintenance cost of TTL loupes is very expensive because updating the Rx of carrier lenses is the same as assembling TTL loupes. Even if you are only updating the Rx inside your loupe optics, this Rx update may take several weeks because your loupes will need to be returned to the manufacturers for the update to be performed. This requires a backup pair of loupes because it is not possible to practice without loupes.
Why SurgiTel? Interchangeable working distance caps allow users to restore the working distance of loupes by replacing working distance caps with shorter working caps. With SurgiTel loupes, users can save on significant maintenance costs (several thousands of dollars for the lifetime of loupes).
Why SurgiTel as Your Partner for Vision Aid Products?
The founding mission of SurgiTel has been to help clinicians practice dentistry and surgery safely by providing ergonomic loupes and eye-safe headlights. As a result of continuous research and development during the last 30 years, SurgiTel can make posture-safe ergonomic loupes for all clinicians with different facial features and can also make the best LED headlights with the best color accuracy and are the safest illumination for your eyes.
SurgiTel’s free evaluation service can help evaluate your working posture and identify the potential blue light hazard of various brands of LED lights. Click here to schedule a free evaluation.
References
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- Valachi, Bethany. Practice Dentistry Pain-Free. Portland, Oregon: Posturedontics Press, 2008. https://posturedontics.com/
- Chang, BJ, The Truth about Declination Angle, ErgoPractice News, June 2020
- Chang, BJ, The hidden cost of Non-ergonomic Loupes and Cool/Blue-Tinted LED Headlights, ErgoPractice News, March 2021
