wild purple finch

Question
there is a purple finch in my front yard that does not seem to be able to see due to a crusty matter covering its eyes.
is there anything i can do for this bird?

Answer
This is most likely a case of conjunctivitis. Infected birds have red, swollen, runny, or crusty eyes; in extreme cases the eyes become swollen shut or crusted over, and the birds become essentially blind.  Birds in this condition obviously have trouble feeding.  You might see them staying on the ground, under the feeder, trying to find seeds.  If the infected bird dies, it is usually not from the conjunctivitis itself, but rather from starvation, exposure, or predation as a result of not being able to see.
You can't so much for this bird, but you can clean up your feeder and any other place birds hang out near your home with bleach, disinfecting it well. Dispose of any seed in the feeder or on the ground. This will help stem the spread of disease.