Designs for Vision are popular, but as posted above, they are cemented to the carrier lenses and are mounted through the lens. That makes changing the carrier prescription more complicated and expensive, if you require a prescription eyeglass lens. There are alternatives in several (many, really) other companies: Keeler, Surgitel, Zeiss, Heine, Sheer Vision and others. Most also make LED illumination lights that can be used with their loupes. This is not so important as a resident, but they are very useful as an attending. For residency, 2.0 -- 3.0x is probably enough magnification and will give you a generous field. Most of those in this range are Galilean designs which are simpler and less expensive than Keplerian prism telescopes, which are generally used for telescopes above 3x. I use up to 4.5x in some of my telescopes for deep orbital work and for DCRs where magnification is more important than field size.
The other factor to consider is working distance. If you do most of your cases standing, longer working distances are better and allow you to maintain a good posture (i.e. not stooping forward to be in focus) If you have longer arms or are taller, longer working distance is better (18in rather than 14 in, e.g.) Conversely, if you operate sitting or are shorter stature, a shorter working distance is better--13-15 in, e.g.) Higher mag favors longer working distance and the relatively smaller angle of view puts a larger area into the sharp focus plane the longer the working distance, where at a shorter working distance with the same mag gives you a smaller field area. So a rule of thumb is that for shorter working distances, all other things being equal, you should use a lower mag if possible.
One advantage of the tilt-up systems (Keeler and Heine make these) is that the telescope pair attaches to the frame with a uniform mount that can allow changing out the telescopes from one type/power to another, so it would be possible to have more than one set of telescopes to exchange depending on the type of case being done. It would also allow you to buy a simpler and less expensive Galilean set for residency but later buy a Keplerian set if you need something with more power or for longer working distances or when you become (more) presbyopic.
So in summary:
Shorter working distance--shorter surgeon/shorter arms/sitting cases--favors lower power
Longer working distance--taller surgeon/longer arms/standing cases--favors higher power
Even the more expensive prism surgical telescopes are relatively simple devices, compared to common consumer optics like binoculars. The focus is fixed, not variable, and despite their costs, most do not have the environmental sealing or fully multicoated optics that even mass market lower priced sport optics have. Because they have to be worn and not held, their design is a collection of compromises. High eyepoint (i.e. long eye relief) requires larger oculars. Large oculars are heavier, so less comfortable in a spectacle. Bright image requires larger prisms and objectives, meaning a bigger, heavier telescope. Smaller, lighter telescopes are easier to wear, but suffer in eye relief and brightness. Metal barrels are durable, but heavier than polymers. Hinged mounts offer flexibility, but at the loss of eye relief. Finding an instrument that fits best for you for the work you plan to do is most important. If you are lucky, you will find something that gets the most of what you need for a reasonable price.
