Coryza? Eye infection?

[EgginaNest]

Hey all. I have a 8 week old Silver Laced Wyandotte that has a gunky eye. I admit it does stink, but she's not sneezing, wheezing, shivering. She's eating, she free-ranged tonight, as well as drinking water. Of course, I've googled all day about Coryza. I gave her a dose of Tylan 50. And am planning to treat it as Coryza. Thoughts, feelings?
Pictures included.

 

[Eggcessive]

Sulmet, DI-MOX, and Albon are all good for coryza treatment.

 

[EgginaNest]

The girls are for entertainment purposes, as well as for eggs for our household. I don't really want to cull them all, am I fighting a losing battle? We have 6 other chickens in the same coop. None are showing signs. If the bigger girls start to show symptoms, should we treat the whole flock with the Tylan?