Depth perception problems - anyone have any experience with this?

Over the years I have noticed every now and then a chicken that cannot seem to peck at the food like the others. One was a chicken I had a few years ago that was blind in one eye. She would peck an inch or so above any food and have to work to "find it."

Now I have another young cockerel. I can see no problems with his eyes, but when he pecks at food, he stops about an inch above. Any treats are quickly gobbled up by the others, so he rarely gets treats unless I sit him in my lap so he can eat. He isn't sick or underweight and is growing at the same rate of his siblings. He seems to have sight in both eyes.

It is certainly not an emergency, so I hesitated to put it under this topic, but I was just wondering if anyone else has experienced this.