When Beginning with Photoshop, one always looks up how to change the eye color. This is because most of the time when taking photographs, you will notice red eyes. Its basic and fun to do. Once familiar with the technique, a lot can be done. Marquee Tool is mostly used to do so, but again all the tools available in Photoshop can do a number of jobs.
To start, you can open your own eye image, or just save this picture to play around with the technique.
Now select the Elliptical Marquee Tool and Set feather to 20px.
Secondly put your cursor in the middle of the eye and press Alt to draw a marquee around it.
Then go Ctrl + C, copy the marquee and press Ctrl + V or simply paste it, a new layer will appear in the layer panel.
Now with the new layer selected, go to Image –> Adjustments –> Hue/Saturation or simply press Ctrl + U and the settings will appear on your workspace.
Next change the Hue / Saturation to the color you like. In this image I am setting the eye color to gray so the Hue is –180 and saturation is set to –100. Press Okay!
Lastly you have successfully changed the eye color.
Gradient Overlay can be used on the top of the same layer, by going into the blending options.