Holly Grant, Project Assistant says:

Hi Jennifer, Crusty, red, or swollen eyes in finches is normally related to House Finch Eye Disease, one that has been around for several decades. You can learn more about this disease here. As for the new affliction affecting birds in mid-eastern states, that is still unknown. It could be a pathogen, it could be related to pesticides, or there could be another cause. For now, if you see a sick bird at your feeder, it’s best to take your feeders down and give them a good scrub (here are instructions). Then, keep them down for a few days to help the sick birds disperse. Cleaning feeders regularly is the best way to prevent the spread of disease at your feeders.