When checking my chicks two days ago, I noticed that the eye color of one had was blueish gray. Now I have noticed that all of them are blueish gray - I googled this because it seemed strange that the color of an iris would change from brown to blue, and I came across "Marek's disease". From what little I was able to understand, the pupil may now change shape - the birds will go blind - the chickens will not thrive - and will end life paralyzed. Is all of this correct? Can I be sure that they do indeed have Marek's disease? Thanks for any knowledge you may share. They came to me through a feed store order, one day old, and were not vaccinated.