Viewfinder magnification?

I find it really hard to see thru the viewfinder of my D rebel/ Ikelite housing setup. Sure, I can see that the fish is IN the picture, but find it much harder to see what details are in focus, not to mention trying to get for example eyes sharp. My eyesight on my "shooting eye" is somewhatr deteriorated, so that further complicates matters. Is there any type of external (or internal) diopter or sportsfinder attachments that couldbe used to create a magnified view of what comes thru the lens? If there is such a gadget, then my credit card stands ready!

( I assume the wireless LDC mask discussed on April 1 is still on the drawing board :wink: )