Decide which photo you will be using - a good candidate is one with a nice resolution, and the eyes clearly visible. This method works best for lighter eye colors, but can be used for darker eyes also.
Below is the image we will be working with.
The first thing we will do is to zoom in one the eye we'll be working on. (Press Ctrl+ to zoom in and Ctrl- to zoom out. Then hold spacebar and click and drag to pan around). The first tool we will be using is the Dodge tool (
). Once selected, choose the Range as Midtones and the Exposure around 20-30%. This will depend on your image, so try different settings. Also, choose a brush size that fits the iris in the image. Then, paint around the iris, making it lighter:
Next, change the Range of the Dodge tool to Highlights, and repeat the process. If you go a little overboard, and the effect is too much, try using Edit > Fade Dodge Tool.
Now choose to Burn tool (
) with a similar Exposure and set the Range to Midtones. With the same brush size(s), go over the borders of the iris to increase the contrast:
As an optional extra, you can use a selection tool to make a selection of the iris, something like this:
Then, right-click the selection and choose Feather. Depending on the size of the photo you are using, you want to aim to blend the selection into its surroundings. For this example, I choose 2 pixels.
Now goto Layer > New > Layer via Copy, and set the Blending Mode of the new layer to either Multiply, Screen or Overlay, depending on which you prefer. You can also play around with the opacity of the new layer to get the right amount of 'wow'.
Original:
Overlay @ 25%:
Multiply:
Screen @ 35% Opacity:
More Tutorials: 
