So I own 17 plymouth rock hens, aged approximately 6 months. I recently noticed that one of my hens was blind in one eye, but contributed it to a rooster that unfortunately disappeared a couple of days before. I noticed today that another hen was blind in both eyes when she didn't come to roost at night. They have been vaccinated for Marek's Disease and I dewormed them about two weeks ago. The lens appears to shattered in the chicken with only one eye blind, and in the other chicken one lens appears to be shattered and the other is rather cloudy. They have a clean chicken coop and free range in our yard. I have both hens separated from the others. What is causing this, and how do we fix it? Any advice welcome.