<aside> 💡 On this page, you will find resources for organizing a loupe fitting session for residents. This page is still a work in progress. If you have resources or insights to contribute, please reach out to Meghal Shah

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The Problem

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What can we do about it?

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The Vocabulary

Loupes Magnifying lenses mounted on prescription or non-prescription glasses.
Declination angle The angle between the magnifying lens and the horizon of the line of vision. A steeper declination angle will require increased downward rotation of the eyes relative to the head, but will help maintain a more upright head position.
Focal length The distance at which the light that passes through both lenses of the loupes converge. This is the point of maximum focus.
Working distance The distance between the lens and the operative field. The higher the magnification, the shorter the working distance. The focal length and the working distance should align.
Magnification The ratio between the apparent size of an object while looking through loupes and the size of that object in real life. Typically ranges from 2.5 - 6.0. Most general surgery residents will opt for 2.5.
Angled or prism loupes Loupes that contain an angled lens such that the viewer can look directly forward but see an image that is physically under them.

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Material

  1. Operating Room with a height adjustable bed.
  2. Stepping stools.
  3. Low fidelity model of operating in a cavity or “hole”. You can use suture kits or knot tying boards to simulate operating to reproduce the actual posture and working distance that the loupes will be used in.

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From the experts:

  1. Pick the lightest weight frame available.
  2. Take sagittal plane photographs of the participants to provide realtime specific feedback about posture.
  3. Measure the angle from the acromion to the ear from the spinal plane. This angle (acromion-to-ear) is a measurement of cervical spine flexion. This angle should be minimized as much as possible to reapproximate neutral position. Ergonomics literature recommends <10º, but given the downward facing nature of operating, this threshold is liberalized to <25º in surgical practice. Decrease this angle by utilizing a slight chin nod to reduce the “head forward” position.

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