Critical
Corneal thinning, usually at the limbus, often in the shape of an ellipse, accompanied by an adjacent focal conjunctival or corneal elevation.
Other
Fluorescein pooling in the area but can stain. No infiltrate, no anterior chamber reaction, mild-to-moderate hyperemia.
Poor spread of the tear film over a focal area of cornea (with resultant stromal dehydration) due to an adjacent surface elevation (e.g., chemosis, conjunctival hemorrhage, filtering bleb, pterygium, tumor, and poststrabismus surgery).