Here is an illustration I drew using this method of drawing eyes.
I would like to draw a lucent and transparent illustration.

 

Draw a rough image to solidify the color image.

First, we will do a line drawing of the eyes.

The ratio of the eyes will be adjusted so that the width of the whites of the eyes is 100% and the width of the black eyes is 50% of that.

With a frontal face, it is difficult to draw the eyes symmetrically, so copy and paste the line drawing part and flip it left and right.

I flipped it left and right and placed it to see the balance.

 

Paint the base color.

If you use too many primary colors, it will be difficult to blend them, so it is recommended to use dull colors.
In this case, I used these four colors as the base color to avoid using too many colors.

Display the rough sketch in the document window, and use the eyedropper to apply the colors.

The color coding is finished.

 

First, we will add the shadow color for the whites of the eyes.

We will add a thin shadow to the top half.

Change the color of the line drawing for the eyes.

Create a new layer on top of the pupil line drawing and clipping it with the color that will be the shadow color of the pupil.
The color of the line drawing has been changed.

Once you have finished changing the line drawing of the eye color, use the airbrush to paint around the eyes.

If you find that you’ve painted too much, select a transparent color. If you find that you have overpainted, you can select a transparent color and use the airbrush to paint the overpainted area to get the eraser effect.

Paint the lower part of the eye with a low-saturation purple.

I changed the layer to a screen layer, changed the opacity to 65%, and adjusted it so that the shadow color of the edge that I just applied is lightly visible.

Create a new layer on top of the line drawing folder.

Draw the mucous membrane part with oil pastels.

Paint the inner corners of the eyes pink, and the lower part of the pupils pink, almost white.

We will add a highlight to the eyelash area.

First, add a round highlight in a low-saturation purple.

Then, use white color to paint inside the highlight that you just painted.
The area to be painted is the area circled in yellow-green.

Paint the tear troughs.

Use the shadow color to paint the tear trough area.

After that, add a fine highlight in white.

Change the color of the line drawing where the hair is hanging over the eyes.

Start with a darker line drawing and paint it with a color closer to white.
This will give the hair a translucent look.

Add highlights to the eyes.

In this case, the eyes are lush, but I tried not to draw the highlights too large.
I put the highlights near the pupil and at the border between the pupil and the white of the eye.

We will add color to the top of the eyes.

Create a new layer and change it to a multiplication layer.
Take the base color of the eyes with the eyedropper and add color to the top of the eyes.
The pupils will now have a sense of depth.

Change the color of the eyelash area.

Create a new layer on top of the line drawing of the eyes and use the airbrush to apply a gradient in red.

 

This completes the painting of the eyes.

I think the eyes made an impressive illustration.
I hope you will give it a try.

(Text and picture by Mido Hachino)