EXAMINATION OF THE CORNEA WITH DIFFUSE ILLUMINATION The cornea can be scanned with diffuse illumination in order to detect many abnormalities. Corneal scars, neovasculization, infiltrates, abrasions, foreign bodies, and other conditions can often be seen with diffuse illumination. These are not to be confused with the light source reflection from the cornea (#1) or the reflection from the crystalline lens (#2).