Where do you put a poorly hen?

I've got a fold away dog cage I use.  Obviously the hen still needs shelter and a safe place to be overnight, like a shed or garage.

If you think there is a worm problem, they all need worming.  The eye problem is a different matter of course.

Flubenvet at the doses you get for home poultry keeping doesn't kill tapeworm Animalfriend.  I think you would need to go to a vet to get stronger stuff, but you need it for the whole flock in my opinion. Tapeworms release hundreds of eggs and the chances are the rest have got them as well. 

I only know Drontal as a dog and cat wormer, but the vet may recommend it in these circumstances.  I've never used it, but I would be wary of administering it without advice if it were my hens.  Presumably the strength of Flubenvet for domestic use is limited to make sure its safe and you can't overdose ?    If the vet sees a sample of the poo, they could have a full worm check and recommend a treatment course.