Abstract and Purpose: As flight simulators have been valuable to aviators, VR surgical simulators will someday be valuable in medical education, both to reduce training costs and provide enhanced physician training [l]. Current surgical simulators rely on real-time volume rendering techniques, and run on hardware costing several hunded thousand dollars. It is currently impossible for these systems to become widespread, as most physicians and hospitals own PCs which cost 100 times less. We previously created interactive software using stereo-paired images of anatomical dissections to more clearly show 3-D structural relationships in gross anatomy [2]. Subsequently we realized that most surgical procedures could be represented using the “peeling away layers” metaphor [3]; in our new program, the mouse is used as a scalpel or suture to cut away or repair layers of the abdominal wall for a hernia repair.

Materials and Methods: Stereo-paired images of surgical procedures were photographed using a Stereo Realist camera, then digitized for display at 640x480 resolution x256 colors. Software for displaying the stereo-pairs and for cutting away layers was created in Borland C++. We used a 486-66 PC with an 8-bit SVGA graphics card, although the program is compatable with a wide variety of PCs. SEGA shutter-lens glasses with an RS-232 serial adapter (available for ~ $100) are used to create the illusion of 3D: the idea is to display the left-eye image and close the right lens of the glasses, then display the right-eye image and close the left lens of the glasses. Our algorithm is:

• Detect and initialize the graphics card;

• Load two GIF files (images) into memory;

• Sit in a while loop;

• Flip between different images;

• Toggle the SEGA glasses;

• If the mouse was struck,

• Create a new pair of images which displays the new surgical field.

Results: In keeping with the “peeling away layers” metaphor, our program displays a sequence of five stereo pairs representing the skin, muscle layers, and spermatic cord in typical hernia repair. The mouse is used as the scalpel to cut away a layer, or as a suture to repair a layer of the abdominal wall.

Conclusion: Although the definition of VR is fuzzy, most agree that the use of a headset to provide enhanced 3D visualization is an essential element. We have created a very low cost, interactive VR application for the IBM PC, which provides a much clearer perception of surgical anatomy than a surgical atlas while remaining comparable in price. We believe that this program could be used to teach hundreds of other surgical procedures. Through VESA programming, this software could be distributed for a wide variety of PC/graphics card combinations. We are excited at the recent availability of low-cost HMDs (head-mounted displays) for the PC, which could be easily adapted to substitute for the SEGA glasses for use with our program.