What causes dark ring around outside of iris?

I noticed my younger brother who received chemo to treat a sarcoma developed a dark ring around the outside of his blue iris.  Then, after I myself had surgery to remove a papillary tumor had dark rings develop around the rim of my own lighter brown/hazel iris.  Can you tell me what causes this?


This discussion is related to Blue ring around the iris of the eye.

[John C Hagan III, MD, FACS, FAAO]

Search the term "corneal arcus" and then google it.

JCH III MD

[Over_Dairy]

Thank you!  That makes sense for my bro because all he could "stomach" during treatment was high-fat Mexican food!  As for me, I guess no more bacon-wrapped Filet Mignon!
Thanks again.

[Over_Dairy]

Just found picture of Kayser-Fleischer Ring here:   http://www.milesresearch.com/main/eyesigns.asp#kayser-fleischerring
And, that sure looks exactly like what's going on.  Also, the explanation is intriguing because it mentions "prolonged cholestasis" as a possible cause and we've both had gall stones in the CBD!  So, I've printed that out to take to my gastro...
  

[John C Hagan III, MD, FACS, FAAO]

I hope not. Wilson's disease is rare and I have seen a K-F ring only once in practice. Of course if you have it then its something you want to know. Hopefully its the much more common arcus
JCH III MD