Are any other birds showing symptoms? If not, it's either an environmental problem or fungal issue.
Chicken with Bubble eyes - Page 2
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I've had the occasional chicken get bubbly eyes, and I've never done anything about it, despite all the recommendations we see on BYC. I don't isolate because once symptoms show up, the others have all been exposed. Sometimes symptoms disappear completely; sometimes they come and go on a particular bird, but they have always been only mild. I've never had more than 2 or 3 birds get symptomatic at a time, and I've never had one die with this. Mine mostly recover, and go on to lead healthy lives, laying normally. That's not to say that serious respiratory illness don't occur. I'm just saying that sometimes bubbly eyes is nothing serious, and in my personal experience it is usually nothing serious.