I'm not going to be any help on the eyesight thing but I've had some slow-to-start lambs that had have needed help getting on the nipple for more than a week. getting the exact right temperature (to the baby's preference) makes a big difference, you can try slightly warmer or slightly cooler to see if it helps. I find they also take the red rubber / yellow screw-on-cap type of nipple better than the black or hard red rubber nipples. if they're spitting the nipple out instead of sucking, it may be too warm. if they're loosing interest after feeding for a while, or shiver after feeding, it's too cold. there's a fair amount of room between those two states, and getting in the temperature groove helps.
how much... depends on how frequent you feed and how big the lamb is. I judge by when their belly feels gently round and full, not bulging, but not soft and tucked up. sometimes the slow-to-start lambs won't tank up, they'll peter out after only half of what they should drink. I give them 30 sec or a minute and try again. sometimes takes 3 or 4 rounds to top them off this way. I also give some drench to the slow-starters, amount based on size, after they've finished their milk.
is there any way to keep this lamb with other ewes/lambs? we keep our bottle babies in the nursery pen with the other moms/babies for warmth and company, provided the other ewes aren't too pushy with them, or knocking them about.
I'm interested to know what you learn... Alicia, if you cross post, would you put the link on here?