I would keep the chick separated untill you know for sure.. Poor thing.. What breed?
Finally returned home late last night. I work early this morning and won't see personally how the blind chick is doing until late this afternoon.
It is in coop and pen with 4 nine-month old Silkie pullets (one is its broody mom Tapioca), the two other chicks that hatched with it, and two chicks that hatched early January. DH moves the chick in and out of the coop when Tapioca takes the other two chicks in or out. Each time he puts the chick at the food dish near the water. He says that he sees it drink and eat but is not sure how often during the day. The chick is a barnyard mix of barnyard mixes of hatchery Barred Rock (roo), New Hampshire (hens), and Easter Eggers (hens). The chick was solid black when I last saw it. It did not have a white fluffy butt like its sibling or any white spot on the head like the older chick of similar parentage did. The chick's parents are siblings from the same roo so that may be part of the cause.
I am hesitant to isolate the chick as long as it is doing well. If it lives to be a hen, then we will probably be keeping it with the Silkies. If it is a cockerel, then it will probably go to freezer camp. If it doesn't make it through the teenage months, then at least it won't be lonely while it is with its siblings and Tapioca.