Danny Mac Eye Designer
The Eye Designer is a versatile Blender Add-on that allows for quick and easy creation of great looking eyes
Watch the tutorial for more information: https://youtu.be/nPK6JlWESM8
Simply click a button and the eyes are imported into your scene. From here you can tweak the iris size, pupil size and apply a realistic cornea bulge by the tweak of a few sliders.
There's also a host of different controls for the iris and cornea shading properties as demonstrated in the video.
A bonus feature is the variety of fake specular highlights to give your eyes that extra pop!