Layers

I will draw it like this.

First,

Create the base.

And then,

Add a layer.

Once added,

Click on the layer

and let's clip it.

Paint only the tip.

And then,

draw the pupil with purple.

Add a darker purple inside.

Then,

add highlights.

Draw jaggedly.

And then,

add cloud-like highlights.

Then,

add a layer.

Click on the added layer.

Then,

click 'Normal'.

Once done,

select this brush.

Paint it like this.

Then,

change the brush to a spray brush.

After painting it like this...

Done!