First thing to do is separate her from all the others and observe bio-security rules. It may be contagious? The only reference I can find in my poultry books associated with cloudy eyes is to Mareks, but there is no mention of crustiness with it which could be just a bacterial infection. If it is simply a localised eye infection your vet will give you antibiotics. There is no alternative to vet treatment and it needs to be quick- today if possible.