Thank you for waiting. The first thing I would do is get rid of the cedar bedding. cedar and pine both contain volatile oils that can irritate the eyes, skin, and respiratory system. They can also lead to liver and kidney disorders. I recommend CareFresh or another paper-based litter.
A discharge from the eye can indicate so many different things that it would be difficult to say exactly what is causing this.Conjunctivitis is a possibility, but there are many others. It could be anything from a slight injury to the earliest sign of an upper respiratory infection. Eye discharge is also common when there's a dental problem, a polyp, a tumor, or abscess putting pressure on the eye from behind. However, since it's only one eye, there's a good chance it's caused by an injury or some kind of irritant that got into that eye.
Guinea pigs do normally have a white eye discharge ("sleep" dirt), but they clean it off themselves. I would get rid of the cedar bedding, and then try the following first aid measures for a few days. Gently clean the eye with a warm, wet cloth. After wiping it, put in some preservative-free saline drops several times a day. The kind used for contact lenses is fine. If the eye doesn't improve within a few days, or if your guinea pig develops a nasal discharge or a cough, or loses his appetite, it would be best to call a vet. Here's a link where you can read more about the various causes of eye discharges in Guinea pigs:http://www.guinealynx.com/eyes.html#discharge
If you end up needing a vet, here's where you can find one who is experienced with guinea pigs/rabbits:http://www.rabbit.org/vets/vets.html
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