The manual X-Y-Z stage under Slit-Lamp microscopes are designed for single handed joystick positioning of microscope. This is smart engineering. As poetry rides on, and strives off of some fantastically written verses, mechanical engineering also lives off of a few fantastically designed mechanics. Well, if you study this mechanism, you'll realize that you have found one of these beautifully written verses from the mechanical engineering's text book. Zeiss is not the best example, because the Swiss made Slit-Lamps are known to be the best.