here is what i know about black in the iris: black specks = toxins (one has appeared for me too, since starting cleansing). depending where they are in the iris map, you can see what part of your body is affected as far as i know.
black spines radiating from pupil: poor digestion, sluggish, toxins not moving well out of bowels. this is only what i read from 1 source though (same book as you read the soil and health one).
my scurf ring seems to be blurring around the edges and getting more milky rather than the very dark opaque it started out. i think it really is starting to go away!!! skin brushing helped me a lot with my skin (actually stimulated my lymph so much i had a detox reaction from it!)
ps sorry did not realise magic glitter already answered your ques bout lines +specks!!