This time, I will show how, with some patience and a tablet, you can produce your own eye textures, applicable to your 3D characters. It's a realistic texture, but it can be simplified, depending of your intention and your character's style. This tutorial will also be able to be taken advantage by those that work with 2D, helping them to understand a little of the Photoshop capacities.
For that texture, I used the 1000x1000 pixels resolution. Approximate time of work to the final result: 3 hours.
Begin creating a new file, square (in that case, 1000x1000 pixels). Fill the background with some tone that have a little of gray (almost white). After, create a new layer and create a circular mask in the center of the image, with close proportions the one in the image on the left:
After deciding on the favorite color for the eye that you will paint (green, brown, blue), fill in the circle with it. After that, create a new layer and through the same procedure, paint the pupil with black:
Using the smudge tool (finger), produce some "blots" as suitable in the illustration below, always from center to outside:
Create a new layer, a new circular selection and paint it with white, according to the image:
Now, use the noise filter (Filter> Noise> Add Noise...) and use the same setup shown:
Now, we will apply another filter: Filter> Blur> Radial Blur... Use the options "zoom" and "best" and put a very high value in "Amount" (100 or close to 100). The result will be this:
Use some option of mixing layers, like Overlay, Pin Light, Screen, or the one that you prefer. After, use the "Liquify..." filter in this layer. Through it, create small irregularities so that your image resembles the one shown:
Duplicate the pupil layer and alter it's color using the menu "Image> Adjustments> Hue/Saturation... " or simply "Ctrl+U". Set the parameters as in the image below:
On this layer, use your ability to create more irregularities, this time, painted with a brush not very wide. Try to get a close result to the shown below:
Copy that layer, set some mixing layer option (overlay, for instance), until obtaining a close result to this:
You can simulate some window reflections with another layer, as indicated below: