Thank you for writing JA with your finding.
This is actually known as corneal arcus. It is normal in the elderly. In a person as young as you this may indicate a lipid disorder. It is possible that it is a benighn disorder, but you will need to have a blood sample drawn to check for a lipid disorder.
If you have a lipid disorder it means your body is not be processing lipids (fats) correctly. This would likely be due to genetics at your age, meaning that you have this as an inherited disorder. You will need to see your physician for testing. Luckily there is treatment for this, which is medications, anti-lipid or anticholesterol medications, as well as monitoring the fats in the diet.
If you have questions or comments please reply so that I or another expert can address them.
Have you already seen a physician for this? There is no otherwise documentation of a blue ring in the eye in the literature. This is very unusual. If you have a picture send it in.
Hopefully this is a benign problem, but it is close enough to corneal arcus to be a possibility so I'd certainly recommend getting lipids drawn, and if that is not a problem see an opthamologist to rule out other problems.
I'll forward this to our opthamologist so that in case he is aware of something like this he can write to you about it.