A note on these--there was no real absolute number of blood vessels to add, so I ended up adding one every 4-5 sc in the blood vessel round, trying to vary the distance between them so as to avoid looking too uniform, with 10-11 in total. Also, maybe I was reading the pattern incorrectly, but I ended up having to add in several more layers to completely finish the eyeball.
The first real difficult section is adding on the blood vessels into the rounds.
Gets a little more difficult slip stitching them so that they lay flat onto the eyeball. This is the interior of the eyeball after slipstitching the blood vessels for several rounds.
The pattern also says to stuff the eyeball after round 13, but I usually ended up stuffing it after 14 or 15--but that's more of a personal choice.
Stitching the blood vessels together. I found that the easiest way for me was to run a length of the same red yarn through all of the vessels, then tie them in a circle with a knot. Then I worked in a spiral towards the tips for an inch or two, adding in vessels as I went.
And this is the final product: