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Surgical Loupes

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Operating loupes are magnifying lenses worn by a surgeon to enhance visualization during surgery. Commercially available surgical loupes provide magnification of an image 2.5–8× the size seen by the unaided surgeon's eye (Ross et al. 2003; Carr and Castellucci 2010; Stanbury and Elfar 2011). Shortening the working distance increases magnification. Loupes are classified according to the optical system by which they provide magnification (Carr and Castellucci 2010).

Simple loupes are analogous to reading glasses and used by jewelers evaluating gems and by hobbyists. One pair of positive meniscus lenses comprises the optical system of simple loupes (Stanbury and Elfar 2011). Although inexpensive, the poor quality of the image produced by simple loupes precludes their use in exotic animal surgery. Additionally, spherical aberrations and purple or green color‐fringing along the margin of the image are serious disadvantages of this optical system (Carr and Castellucci 2010; Stanbury and Elfar 2011).

Compound loupes, also known as Galilean loupes, are the most commonly used loupes and composed of two pair of magnification lenses separated by a layer of air. Chromatic anomalies are not observed with this system, but spherical aberrations may be seen at magnification levels greater than 2.5× (Carr and Castellucci 2010; Stanbury and Elfar 2011). Compound loupes are less expensive than prismatic loupes and are widely available from numerous medical optics vendors.

Prismatic loupes, also known as Kelperian loupes, provide image amplification using Schmidt prisms. These prisms fold and lengthen paths of light through the loupes, yielding improved magnification, expanded field of view, deeper depth of focus, and longer working distance than other optical systems (Carr and Castellucci 2010; Stanbury and Elfar 2011). Although prismatic loupes are traditionally very heavy and much more expensive than compound loupes, recent innovations have permitted the development of prismatic loupes that are lighter weight and more comfortable (Chang 2014b).

Surgery of Exotic Animals

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