Eye problem

[IRL]

Hello
One of my 6 day old call ducklings has a problem with its eye. He/she acts normally, but has its left eye closed frequently for periods of about 30 seconds. He/she can open the eye with no problems, but just seems to like it closed a lot. There is no discharge or irritation around the eye that I can see. What's wrong?
Thanks

 

[4-H chicken mom]

Is it possible that it has something in the eye, sawdust, shavings, piece of food.