Is it just one eye? Is it crusty? And does he have any other respiratory issues as well?
If this is JUST the eye and there are no other symptoms, you can use Terramycin Eye Ointment. It is an antibacterial medication that can be used on dogs, cats, birds and even yourself. It will clear up most eye infections. You can get it at many pet supply places,
Amazon and I think even Walgreens carries it.
If there are other respiratory issues going on as well, you will need to start him on some antibiotics put in his water. One of the "cyclines" work well for respiratory ailments.
If he is being picked on by the others, resulting in this eye infection, you will need to find out who is being the aggressor in the cage and remove them.
Oh, and welcome to BYC and the quail forums!