Considerations in Purchasing Deflection Loupes

Print Friendly, PDF & Email
ErgoPractice News – June 2022
By Jin Chang PhD


Loupes can offer two benefits to users. The first benefit is the improved vision (i.e., magnified images) and the second benefit is the improved working ergonomics (i.e., safe working posture). All loupes can provide users with the first benefit, but many loupes cannot provide users with the full second benefit. The use of loupes with proper working distance can prevent lower back pain, but many of those loupes have become the main cause for chronic neck pain. Today, over 90 percent of dental professionals and surgeons have been experiencing chronic neck pain. To help alleviate the chronic neck pain, SurgiTel has developed all three types of ergonomic loupes: customizable straight FLM (front-lens-mounted) loupes, straight TTL (through-the-lens) loupes, and Deflection loupes.1

Straight Loupes and Deflection Loupes

Loupes can be classified into two styles: straight loupes and deflection loupes. There are two main differences between straight loupes and deflection loupes. First, the working distance with deflection loupes is longer than the working distance with straight loupes. Figure 1 shows working postures: (a) with non-ergonomic straight loupes, (b) with SurgiTel ergonomic straight loupes, and (c) with deflection loupes.  The average working distance with non-ergonomic straight loupes is about 15”, the average working distance with SurgiTel ergonomic straight loupes is about 18.5”, and the average working distance of deflection loupes is about 22”. This means that deflection loupes require a higher magnification power to compensate for the effect of the increased working distance on the image size formed on the retina of the eyes.

Second, when using deflection loupes, the sightline of the eyes is not parallel with the line of magnified images similar to using surgical microscopes. Using deflection loupes is not a natural direct hand-eye coordination and may require a long period of learning.

(a) Working posture with non-ergonomic straight loupes.

(b) Working postures with SurgiTel ergonomic straight loupes.

(c) Working postures with deflection loupes.

Figure 1: Working postures with different loupes

Who May Need Deflection Loupes?

SurgiTel’s ergonomic straight TTL loupes have helped users work with safe postures by maintaining a head tilt less than 20 degrees, preventing chronic neck pain.2

Most clinicians can achieve their safe working postures with SurgiTel ergonomic straight loupes, but clinicians who do not want to tilt their heads due to their serious chronic neck pain can choose deflection loupes.

Considerations in Purchasing Deflection Loupes

If you have not tried SurgiTel ergonomic straight loupes which can help you work with a safe neck posture, you may try SurgiTel ergonomic straight loupes first. Using straight loupes is natural and does not require a learning curve. If you want SurgiTel ErgoDeflection™ loupes, you may exchange the straight loupes with ErgoDeflection loupes within a trial period.

If you want to purchase new deflection loupes to replace your current loupes, you should estimate the magnification power based on your new working distance and consider ergonomic issues associated with various brand deflection loupes. Figure 2 shows features of four (4) brand deflection loupes.

Figure 2: Features of four brands of deflection loupes.

  1. Calculation of required magnification power: You can find the required magnification power of deflection loupes by multiplying the magnification power of your current loupes with the ratio of your increased working distance with deflection loupes over your working distance of current loupes, see Figure 3 for an example.
  2. Ergonomic tests: You should make ergonomic tests by examining targets through deflection loupes. If loupes force you to tilt your head backward to see certain parts of the operating objects or do not allow you to see certain parts of operating objects, you should not purchase those deflection loupes. SurgiTel ErgoDeflection™ loupes (patent-pending) are designed to allow users to see all or most parts of operating objects.
  3. Eye protection: You should make sure that frames and eyeglasses are designed to properly protect eyes. SurgiTel frames and eyeglasses are designed to protect eyes.
  4. Working distance and conversion angle: Well defined focuses of optics associated with the conversion angle are very important to create high quality images. LumaDent deflection loupes do not have a well-defined working distance, allowing customers to adjust the focus of each optics separately by rotating the objective lenses, but this may create a misalignment of the convergence angle and different focuses of two optics, resulting in poor images. SurgiTel offers interchangeable working distance caps which create well-defined focuses and allow users to adjust the working distance.

Figure 3: Example equation on how to find the required magnification power of deflection loupes.

Why Choose 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 all types of posture-safe ergonomic loupes for all clinicians with different facial features and offer the top LED headlights that provide the best color accuracy and are safest to eyes.

Please note that SurgiTel’s free evaluation service can help assess your working posture and identify potential blue light hazards of various brands of LED lights.


  1. Chang, BJ, Success at SurgiTel: 30 Years of Vision & Ergonomics, Link:, ErgoPractice News, July 2018
  2. Valachi B, Practice Dentistry Pain-Free, Posturedontics Press, Portland, OR, 2008,