Scroll mice took over about the same time that optical mice took over. The overlap between the technologies is almost complete.

Yeah, you can click the wheel, but it's not a real middle button if you happen to be in a program that makes heavy use of the middle button, it's annoying.

Up to a few years ago HP sold the DY651A 3 button optical mouse without scroll wheel for just $13 but good luck finding one today. Appears to have been USB-only.

So where we land, turns out, is the Contour Perfit.

Contour Design is out of business. But the mice are on eBay and not really sought after so they are cheap. I bought a pair for less than $20 combined (from two different sellers).

They specialized in ergo weirdness. The Perfit is available in left and right handed, sizes S, M, L and XL in right handed and S, M, L in left handed. With or without scroll wheel, on the side, operated by your thumb. All of them have a back/forward toggle for your thumb.

Allegedly these are 1200dpi optical mice. I have played with mine just a bit, and they seem to be very good.

I bought size "L". And if you saw one on a desk, you'd say "Wow, that is a large mouse". I have trouble finding gloves that fit me. I think if i found some XL size, i would be able to rest my whole hand on them.

Neither of them came with a USB-F to PS2-M adapter, but i dug out an old Microsoft branded (green) adapter, and it works fine with that, even plugged into an old SGI Indigo2.