Open the image you want to modify. This is mine:

Now zoom to around 6-700% to see the eye extremely large in order to make an accurate selection. Take the pen tool and make the eye shape like in my example. It doesn't have to be perfect. Now right click and choose "Make selection". In the dialog box that will appear, choose
a feather radius of 2-3 pixels (depends on the resolution of your image).

With the selection made, take the rectangle selection tool right click again on the selection and choose "Layer via copy". You'll notice a new layer being created.

Now select this layer you created and hit CTRL+U to bring up the Hue/Saturation menu. Enter these values: Hue: 202, Saturation: 54, Lightness: 0 and check the "Colorize" option.

Here is the result:

Make the same for the other eye. You're done: