Hi Steve, the design of theses buttons (no rocket science here BTW) has been around Aquatica for a couple of decades, and rating them for different depths is somewhat of an easy task for the average bloke with any background in engineering.
Since we do quite a bit of camera housings for technical divers with depth of 425ft plus, we do tend to pay attention to that particuliar aspect of the controls. at this kind of depth, the dollars per minutes clock is ticking and you sure as hell don't want your user to be fiddling around with compressed buttons.
If the buttons are not the limiting factor of 90 m for this housing, what is? If it is the housing, there is not much to do about it, but if it's the lens, maybe a stronger lens could be fitted. If its the PC lens covering the lcd a thicker lens could be fitted, but the button pins would need to be longer. Please advise.