The sunken eye appearance looks like possible mycoplasma gallisepticum (MG.) It is a chronic respiratory disease that can cause pinkeye and sinus infection. The pupil appears to be cloudy, which could be a cataract, or it might be related to MG. You can try to get testing to confirm MG. Here is some reading about it: https://extension.umd.edu/sites/ext... Mycoplasma gallisepticum (MG) Infecti....pdf