If eyes have ocular immune privilege, how come so many environmental allergies manifest themselves as itchy/watery/swollen eyes?

Question

If eyes have ocular immune privilege, how come so many environmental allergies manifest themselves as itchy/watery/swollen eyes?

In: Biology

Answer 1

Environmental allergies are generally speaking not evolutionarily advantageous. General irritations are. Since the risk of losing an eye is a “big deal” the supporting systems are tuned to go all in on flushing irritants out.