Diseased Bird: Multiple cardinals with infected eyes

We had seen house finches with eye disease through the summer/fall. Occasionally we might see a pine siskin with the same issue. We tried cleaning the feeders and getting finch specific feeders (socks) to keep them from other birds but starting in November we have noticed multiple cardinals, male and female, all with 1 eye either swollen, bald, or shut/blind which concerns us that we are facilitating the spread from finch to cardinal if this is finch eye disease. It’s not realistic for us to clean the feeder daily, we can only do so weekly but there are so many birds every day that if the feeders are the vector, we don’t see how we can continue using feeders responsibly. We also have a water fountain that we do rinse out and clean with rubbing alcohol but maybe that’s also the culprit? Not sure what we will do but we probably will take down all the feeders and just put seeds on the ground…would that help them spread out and not infect each other?