There are several extra intestinal manifestations of Crohns that deal with the eyes. Uveitis, scleritis, and episcleritis are a few of them.
It is important to see an ophthalmologist about any eye problems when you have CD so that the issue can be dx'ed and treated properly. Some eye problems that come with crohns can be serious.
My son has episcleritis, it doesn't cause permanent damage but does at times require treatment.