my rat has an eye infection?

Question
my name is zoe and i have two female rats. they are both perfectly normal but Since about one or two weeks ago she has had a lot
of porphyrin around one of her eyes. The other rat has nothing wrong
with either of her eyes. Along with the porphyrin, there is  little
bit of black stuff, that looks like dirt. She also sways back in forth
from time to time.  Besides that, they both act normal. Is it an eye
infection? I read on the internet the porphyrin is caused from stress
but nothing stressful has happened to them.. Any thing I can do to
help? Please Write back!

Answer
Is the eye ball itself normal?

As for swaying her head, please read my website and the page on swaying. Its pretty interesting. Let me know if the eye itself looks healthy.

Is she eating and drinking ok?  Anything new in the cage, such as a switch in litter/bedding?

Here is the link to my  site and the page on head swaying:

http://www.sandyscrittercity.com/myratswaysherhead.htm