Sharpen Detail Areas, Like Eyes?

Get the Sharpen tool from the Toolbox (it’s nested with the Blur tool), then up in the Options Bar, make sure the Protect Detail checkbox is turned on (so it’s using the new math, and by the way, the mathematical algorithm behind this tool is the best sharpening in all of Photoshop). Now, simply paint over the areas you want sharpened. I use this on the irises in portraits and it works wonders. To help you see a before/after, you might want to press Command-J (PC: Ctrl-J) to duplicate the Background layer first, then apply the sharpening. You can then click on the Eye icon to the left of the duplicate layer to toggle it off/on, so you can compare it to the original. That way, you don’t accidentally overapply it.