The Power of Gray - The Photoshop: Professional Retouching and Compositing Tips, Tricks, and Techniques - page 146

Figure 2.73 The dark lighting doesn't show the eye texture and color.
1. With the image open in Photoshop where you want to enhance the eyes, add a new
blank layer, and name it eye detail . With the Elliptical Marquee tool ( Figure 2.74 ) ,
hold down the Shift key and drag out a perfect circle around the iris ( Figure 2.75 ) .