We’ve used Adobe Photoshop to complete this process, which is available separately or as part of Adobe Creative Cloud. Some students are eligible for an extended free trial of Creative Cloud, and there are also ways to get Photoshop for free.
Select the Pencil tool and draw the outline of the eye, eyelid, and eyebrow.
Use the Eraser to remove the top of the circle.
Draw a donut shape on the black iris.
Dab a few pure-white highlights on the top of the iris.
You could reshape the outer edge at this point, too.
Add some to the outer edges of the white eyeball because they are in shadow, too.
Touch the shadow lightly with the Smudge tool for smoothness.
Note how they clump together in triangular shapes. Use a thin setting, and go over the same areas repeatedly to create thick lashes — thicker on top than on the bottom.
Be sure to make the direction of the lashes change as you move from the outer edge to the centre, to the inner eye.
Add smaller hairs to the eyebrow.
Between the bottom of the eye and the eyelashes there is a strip of pale skin; a thin eraser line works well to depict this.