SurgiTel’s Compact Prism Loupes Vs. Designs for Vision’s Panoramic Loupes

ErgoPractice News – December 2021
By Jin Chang PhD


Many U.S. customers and international distributors have reported that sales reps of Designs for Vision (DFV) are claiming that field sizes of their new patented “Panoramic Loupes” (3.5x and 4.5x) are double of other expanded field loupes of its competitors. This claim is not true, as field sizes of DFV’s new Panoramic 3.5x and 4.5x loupes are double the field sizes of their classic style 3.5x and 4.5x loupes.

Figure 1 shows SurgiTel’s Compact prism loupes and DFV’s Panoramic loupes. Figure 2a shows magnified fields of DFV’s various loupes and Figure 2b shows magnified fields of SurgiTel’s Compact prism loupes (3.5x/EVK350) and (4.5x/EVK450) against magnified fields of DFV’s Panoramic loupes (3.5x and 4.5x). As shown on the right of Figure 2, field sizes of SurgiTel’s patented “Compact prism loupes” (3.5x and 4.5x) are larger than field sizes of DFV’s patented “Panoramic Loupes” (3.5x and 4.5x). SurgiTel’s Compact prism loupes offer other practical advantages over DFV’s Panoramic loupes. Before we discuss advantages of SurgiTel’s Compact prism loupes over DFV’s Panoramic Loupes, we will review types of loupes and marketing names of loupes created by DFV.


Figure 1: Left is SurgiTel’s Compact prism loupes and the right is DFV’s Panoramic loupes.

Figure 2: (2a), Magnified fields of various Designs for Vision’s loupes, (2b), Magnified field of SurgiTel’s Compact prism loupes are added (green).

Types of Loupes

Loupes can be classified into two types based on optical designs. Figure 3 shows two loupe optics types. The first type is Galilean loupes which use a telescope optics design invented by Galileo who was an Italian astronomer and physicist. Galilean telescopes consist of two optics groups — positive objective optics and negative eye-lens optics. The second type is Keplerian loupes which use a telescope optics design invented by Kepler who was a German astronomer and mathematician. Keplerian telescopes consist of two positive optics groups and a prism between two optics groups which rotates the image. The main functional difference is that Keplerian telescopes can offer a larger magnified field than Galilean telescopes. Galilean optical designs are used for low magnification power loupes (2.0x to 3.0x) because the field size of higher power Galilean telescopes is very small. Keplerian designs are used for high magnification power loupes (3.5x and higher).

Figure 3: Optics of Galilean loupes and Keplerian (or prism) loupes.

Names Created for Marketing by DFV

Let’s review names of loupes created by DFV for their marketing purpose such as “Standard Field Surgical Telescopes,” “Expanded Field Surgical Telescopes or EF Surgical Telescopes,” and “Panoramic Loupes.” DFV has classified their loupes (or surgical telescopes) into three types based on field sizes. Standard Field Surgical Telescopes are Galilean loupes which offers the smallest field size. Expanded Field (or EF) Surgical Telescopes are Keplerian (or prism) loupes which offer larger fields than Standard Field Surgical Telescopes (Galilean loupes). DFV might recognize that the field size of SurgiTel’s patented Compact prism loupes is significantly larger field than their classic style expanded field loupes. Thus, DFV designed new Keplerian loupes which offer similar fields offered by SurgiTel’s Compact prism loupes. Because DFV cannot use SurgiTel’s patented optical design concepts, DFV has used a more complex design which requires more optical elements. DFV created a new marketing name of “Panoramic Loupes” for their new Keplerian loupes, which offers field sizes similar to field sizes of SurgiTel’s Compact prism loupes.

Practical Advantages of SurgiTel Compact Loupes

SurgiTel’s patented Compact prism loupes offer circular fields and DFV’s patented Panoramic (prism) loupes offer rectangular fields according to the diagram which shows field shapes, but viewable field sizes are similar. Let’s review practical advantages of SurgiTel’s Compact prism loupes over DFV’s Panoramic loupes.

  1. Superior ergonomics: Using patented frames and manufacturing technologies, SurgiTel can offer truly ergonomic loupes to any clinician, helping prevent or alleviate the neck pain.
  2. More frame choices: Oakley Radar frames and SurgiTel titanium frames (patented) are available for Compact prism loupes. These frames are very stable for high magnification loupes and offer good eye protection as well as provide maximum comfort.
  3. Custom nose pads for maximum comfort to wear: Single nose pads do not fit all nose types. SurgiTel offers several patented custom nose pad options, called Ergo Fit Nose Pads, for various nose types.
  4. Lighter weight: The weight of DFV’s 4.5x Panoramic loupes is about 130g and the weight of SurgiTel’s 4.5x Compact prism loupes is approximately 85g.1 The weight of Panoramic loupes is approximately 50% heavier than Compact prism loupes.
  5.  Through-The-Lens (TTL) or Front-Lens-Mounted (FLM) mounting options:  TTL offers larger fields, but FLM offers more flexibility to users by allowing users to customize their viewing angle for various cases.
  6. Optimum field size with SurgiTel’s custom nose pads: If you want to optimize the field size, SurgiTel’s custom nose pads allow you to optimize the field size by adjusting the space between loupe optics and eyes.
  7. Easy adjustment of working distance with working distance caps: If you want to create different working distances for different patients or procedures, you can adjust working distance using interchangeable working distance caps.
  8. Restoring the working distance that is increased due to aging eyes with interchangeable working distance caps: Aging eyes may require reading glasses.2,3 The power of reading glasses can rapidly change from 0.25 diopter (age 40 to 45) to 2.5 diopter (age 55 to 60). With aging, you might notice that the working distance of loupes has increased. If you want to restore the original working distance of loupes, you must add reading prescription to loupe optics. Adding a reading prescription to most brand TTL loupes must be done by manufacturers – which includes lost time and updating fees. However, the working distance of SurgiTel’s TTL loupes can be easily changed by replacing the current working distance caps. Therefore, there is no loss of time and no updating fee. With SurgiTel’s TTL prism loupes, you can save thousands of dollars restoring the working distance of loupes.
  9. Increasing the effective magnification power of loupes with interchangeable working distance caps: Eyes can see better by getting closer to objects because the image projected onto the retina becomes larger as the object distance decreases. Loupes just magnify the image projected onto the retina. If you deduce the working distance of SurgiTel’s prism loupes with interchangeable working distance caps, you can increase your visual acuity. If you decrease the working distance by 20%, you can see 20% better with line, 36% better with area, and about 50% better with 3D objects. SurgiTel’s prism loupes can be used as multi-vision loupes.

Why SurgiTel is Your Partner for Your Vision Aid Products

The founding mission of SurgiTel has been providing clinicians with truly ergonomic, posture-safe loupes and eye-safe LED headlights. During the last thirty years, SurgiTel introduced many world-first vision aid products based on patented concepts; including customizable FLM loupes, ergonomic frames, truly ergonomic TTL loupes, true-color LED beam-forming optics which allows SurgiTel to offer eye-safe LED headlights with the best color accuracy, LED lights with no-touch switching, multi-vision loupes with interchangeable working distance caps, interchangeable custom nose pad systems, and loupe-mountable digital cameras (SurgiCam® HD). SurgiTel offers unique benefits which may not be available with other brands as follows:

  1. SurgiTel offers the most magnification options (2.5x to 10x)
  2. SurgiTel offers all magnification loupes with either FLM style or TTL style
  3. SurgiTel offers the most LED light options (warm, neutral, and cool) with various models (wired, wireless, and no-touch switching)
  4. SurgiTel offers truly ergonomic loupes to any clinicians with various nose types which offer truly ergonomic benefits over deflection loupes.
  5. SurgiTel offers a free evaluation service — posture analysis with your current loupes and potential blue light hazard with your current LED lights

SurgiTel’s free evaluation service can help evaluate your working posture and avoid the potential blue light hazard of various cool brands of LED lights. Click here to schedule a free evaluation.


  1. Reality, Outlook of Panoramic Loupes (Vision Aid – Magnification Loupes), 2019. Note that this was a preview and did not compare these loupes with other brand loupes.
  2. American Optometric Association, Adult Vision; 41-60 years of age
  3. Sun F, et al, Changes in Accommodation with Age: Static and Dynamic, American Journal of Optometry & Physiological Optics, 1998, Vol. 65, No. 6, pp 492-498