Diseased Bird: American Goldfinch eye disease

I noticed this American Goldfinch at my feeders on december 25, 2013. Matted feathers on cheeks and on top of head, both eyes were , the right more than the left. Bird was quite lethargic, not eating much and picking up some seeds underneath the feeder. It got less and less active over the three following days, have not seen it again. The other goldfinches have not shown any sign of disease yet.