One of my chickens has gone blind - help!

[Chrissy5555]

Hi, I have four chickens, they are all 3yrs old and I have had them from pol.

This spring I have noticed that one of them (a Cream Legbar) has gone completely blind. On close inspection there is no sign of anything wrong with her eyes; they are not cloudy or swollen, they just look exactly as they always have. She is managing well, she can find her food and water and when I let them out in the garden she just pecks randomly and manages to find the grass. She is still laying eggs. Does anyone have any experience of this or have any idea what may have caused it?

Many thanks.