ErgoPractice News logo September 2016

3 Uses of SurgiTel Working Distance Caps

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ErgoPractice News – September 2016
By Jin Chang PhD

Use SurgiTel’s Unique Working Distance Cap System to Adapt Your Loupes to Your Work

SurgiTel has developed and patented a technology for easily adjusting working distance by using “Working Distance Caps.” These caps are used on both our Galilean and prismatic loupes (Figure 1) to change the loupe working distance to be closer or farther.

There are several applications of working distance caps. Let us explore three of them

1) Working Distance Creep

One application is to compensate for a change of prescription. If clinicians wear prescription glasses and try a pair of loupes not made for them, the working distance they experience will be either longer or shorter than the designed setting.

If our eyesight/prescription changes over time, what will happen? Even if we do not wear glasses regularly we will all eventually experience age-related presbyopia, which is treated with reading glasses or drug store reading glasses (a.k.a. cheaters).

If we do not adjust for a changing eye prescription or developing presbyopia our working distance will slowly change. This is what we refer to as “Working Distance Creep.”

If you have trouble seeing your target in focus where you used to, measure your current working distance range and compare to the distance at which your loupes were first set. If your desired working distance is far from the current center of the range, contact SurgiTel to try some working distance caps which may help!

2) Different Procedures

Some clinicians will work on different patients at different working distances. You may not be able to use your loupes for different procedures without hunching over if one of the working distances is outside of your loupes’ depth of field.

With working distance caps, the clinician can use the loupes with the most comfortable posture for multiple procedures even though they require significantly different working distances.

If you perform different procedures at different working distances, contact SurgiTel, and try one set of working distance caps for each procedure. Do not be forced to forgo your loupes or, even worse, be forced to adjust your posture and compromise your ergonomics.

3) Multi-Magnification Concept

Clinicians Report notes that at different working distances images will appear smaller or larger.1 How does this effect work?

Imagine you are on a street with two cars in front of you (Figure 2). 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. 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.

For example, some dentists will work on a patient at a certain distance and work on a prosthetic for the patient which requires to see detail. With working distance caps they convert their loupes into a higher power loupe by shortening the working distance. If the clinician were to shorten their working distance by 20%, they would experience an increase in magnification effect by more than 20%. As if one was standing closer to the cars, the clinician will perceive greater detail.2

With working distance caps you can use SurgiTel loupes as multi-magnification loupes.

Contact Us

For more information about working distance caps, you may contact your local representative. Or you can contact me if you have any questions. My e-mail is Please consider me your resource!


  1. “Clinical Guidelines for Selecting Loupes.” Gordon J. Christensen Clinicians Report. Clinicians Report, August 2016.
  2. Chang, Jin. “Guidelines for Selecting Clinical Loupes.” SurgiTel. ErgoPractice News, August 2016.
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