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