Here is a good article to read:
https://extension.umd.edu/sites/extension.umd.edu/files/2022-04/FS-1008%20Recognizing%20and%20Preventing%20Mycoplasma%20gallisepticum%20%28MG%29%20Infecti....pdf
Have you added any new chickens to your flock recently? It looks like conjunctivitis, which can be from a respiratory infection, such as MG (mycoplasma gallisepticum) a chronic disease. I would get some saline or eye wash at your pharmacy, and flush the eyes twice a day. Then put a small dab of...