I am not sure if this will be helpful or not - I searched "cloudy eyes chickens" in the merck vet manual and came up with 282 results - but you might be able to narrow down the search with more key words/symptoms.
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/204601.htm
Maybe it...
I do not know either but:
What are you feeding - could there possibly be moisture or mold in the feed?
Do they freerange? Any moldy or toxic plants in the yard - access to compost or molding hay/straw?
Any pesticides used - by you or neighbors?