Here is what I do to brighten eyes. I am sure there are other ways. But I wanted to share how I did it. Hope this helps. I am using CS5 as an editing software. You can ask me any question you don't understand. I want to help
Open the image you want to edit and adjust accordingly in ACR then bring it to PS. I took this picture this morning. My kids have dark brown eyes - so it's hard to get that nice looking bright eyes.
Choose the lasso tool on the left. Make a figure eight to chose the eyes. You can see it with the marching ants that circle his eyes.
Right click the eyes and select it via layer. It should create another layer in your palette to the right.
Chose the layer that you just created and click on the screen layer mode
On that same layer click on bottom to add a layer mask. Then chose the paint brush to mask back the face.
Clean up picture - ran noiseware, got rid off the yellow cast on his neck. Then sharpen.