Wednesday, September 10, 2008

Surgical Loupes

I received my first surgical loupes as a first year plastic surgery resident. They are 2.5X loupes made by Designs for Vision. I still have and use them. My second pair of loupes was a 4X from Zeiss which I find heavy and difficult to wear. It is exciting to get your first (and next pair and next) pair of loupes! It is also humbling to wear them the first time and get nauseated because you moved you head too fast and too often. Practice at home with anything -- reading, sewing on a button, disarticulating a chicken wing, just looking at your fingers.






I found the following history of surgical loupes in the chapter on "The History of the Operating Microscope" in the book The History of Modern Cataract Surgery by Marvin L. Kwitko, Charles D. Kelman. You can read it on-line as part of Google's eBooks and see the pictures there of the early loupes.

The history of the surgical microscope dates back to 1876, when simple loupes that attach to the spectacle frame or to a headband became available. These were made of convex lenses that were decentered to allow convergence and to use the prismatic effects of the periphery. C Von Hess used such a loupe together with an electrical illumination device attached to a headband. In 1886, a mechanic named Westien constructed a binocular instrument from two loupes to be used by a zoologist. Zehender later attempted to modify this instrument for use in ophthalmology, giving rise to the Zehender-Westien double loupe. It had a firm base and a lens for lateral focal illumination. Further development of a binocular magnifying instrument progressed along two pathways: one for diagnostic purposes and one for surgical use, leading to the eventual development of the slit-lamp and the corneal microscope. This instrument gave a magnification of 5X-6X, but had to be worn on a headband, which was one of the drawbacks of these original surgical magnifiers. The instrument was heavy and, although Westien tried to reduce the weight of these loupes to facilitate their use, it remained too heavy for the surgeon, and, hence, never became popular.

By 1912, Von Rohr and Stock had constructed a spectacle loupe that was lighter and less magnifying than Westien's. This had a working distance of 25 cm and a magnification of 2X. Gullstrand was the first to use these loupes of Von Rohr. This led to the development of a binocular loupe that could be attached to spectacles and bifocals, a model that is still used today by ophthalmic surgeons for a variety of surgical procedures. By simply tilting his head, the surgeon can view the field either through the spectacle lens or through the loupes, thereby allowing him to make use of the magnification only when needed during the procedure. It was found that a magnification of more than 2X was not desirable, due to the fact that the slightest movement of the head would cause large movements of the image because of the high magnification. These movements led to difficulties in handling tissues. Furthermore, optical principles prevented a magnification of more than 2X with these loupes. It therefore became evident that a stable device was needed for higher magnification in surgical procedures.

Binocular surgical loupes are used by many surgical specialties. There are times when they are preferred over the operating microscope. These would include any procedure when the patient's position and /or surgeon's position make it difficult or impossible to use the microscope. Other times, not as much magnification is needed to warrant the use of the microscope. The microscope is necessary when doing vascular anastomoses on children or vessels less than or equal to 1.5 mm.

Wearing surgical loupes can be a challenge, especially in long cases. The higher the magnification, the heavier they are. These are the common problems encountered when wearing them:

  • Slippage of the glasses down the nose -- Anyone who has ever worn glasses know this issue. It is worst with the added weight of the loupes. This can be decreased by using tape to attach the browbar of the glass frame to the forehead. Another trick is the use of a long cord or band attached to the earpieces and tightened behind the head. This can be difficult to work with if you add a headlamp into the mix. The newer loupes have a built-in or clip-on headlamp.
  • Postauricular pain -- Increased by the length of time the loupes need to be worn and be the weight of the loupes. This can be helped by preventing slippage and by padding the ear pieces.
  • Discomfort on the nasal bridge -- This is dependent on the nosepiece, the weight of the loupes, and the length of the procedure. If possible, change the nosepiece or pad it.
  • Fogging of the glasses -- This is caused by breathing behind the mask (which can't be helped). You can decrease or prevent the fogging by taping the top of the mask to your skin creating a barrier in this area. It is best to use paper tape to prevent skin irritation from the tape/adhesives.

There are many companies that make surgical loupes. Here are a few:

Designs for Vision

Keeler Surgical Loupes

Sheer Vision

Surgical Acuity

Zeiss

REFERENCES

A Practical Guide to Surgical Loupes; J Hand Surg (Am), 1997 Nov: 22(6):967-74; Baker JM, Meals RA

Comparison of the Operating Microscope and Loupes for Free Microvascular Tissue Transfer; Plastic & Reconstructive Surgery. 95(2):270-276, February 1995; Serletti, Joseph M. M.D.; Deuber, Mark A. B.A.; Guidera, Paul M. M.D.; Reading, George M.D.; Herrera, H. Raul M.D.; Reale, Vincent F. M.D.; Wray, R. Christie Jr. M.D.; Bakamjian, Vahram Y. M.D.

Keeping Spectacle-Mounted Loupes on Comfortably; Plastic & Reconstructive Surgery. 99(2):591,592, February 1997; Graham, Kenneth E. F.R.C.S.(Ed), F.R.C.S.(Glasg)

How to keep your glasses on painlessly(Letter); Plast. Reconstr. Surg. 69: 1026, 1982; Zuker, R. M.

Adhesive Bands to Prevent Fogging of Lenses and Glasses of Surgical Loupes or Microscopes; Plastic & Reconstructive Surgery. 117(2):718-719, February 2006; Karabagli, Yakup M.D.; Kocman, Emre A. M.D.; Kose, A Aydan M.D.; Ozbayoglu, Ceyla A. M.D.; Cetin, Cengiz M.D.

5 comments:

Bruce said...

How timely! My 25-year-old DFV loupes are falling apart as well as becoming extremely un-fahshionable. Did I mention the need for bifocals??

make mine trauma said...

So, if you wear contacts, do you judge your loupes strictly on magnification? And, if you wear glasses, do your loupes have to also correct for your eyesight?

rlbates said...

The loupe part of the glasses are just for magnification, not correction of your vision. That's not a problem for looking through the loupe into the field, but can be an issue with the remaining "glass" field which can be "corrective" if needed (ie near-sightedness).

DrB said...

I LOVE my loupes. I got them during fellowship, and feel lost without them.

But I don't think I'll ever forget the first time I used loupes during residency with a plastic surgeon on a hand case (how telling!), and actually jumped when his hand came into the field to cut a suture. How embarrassing!

Recently, I forgot my loupes and really thought I would have to go home to get them. Fortunately, the OR had an extra pair(?!). They were old, and not nearly as fashionable as mine, but they made me much more comfortable than going "naked." :)

Preethi said...

Ocutech Inc.has developed a really small keplerian/prismatic telescope that can be used as surgical loupe, while it gives the same image quality and field of view as a prismatic loupe, it is almost 1/4th the weight of traditional Designs for vision prismatic loupes. Its called the VES-Mini.