Dellen Thinning Seen with the Slit-Lamp Microscope (Photo)

This slit-lamp photograph shows a localized area of corneal thinning. This thinning, called a “Dellen,” occurs entirely from localized dehydration. In this case, the culprit is an area of conjunctival swelling next to the limbus.

Now, in this photo the chemosis is hard to appreciate (you may want to watch the dellen from chemosis video from which this clip was taken). The conjunctival swelling forms an elevated area that interferes with the normal tear-film blink mechanism. As the upper eyelid lowers, the bump gets “hit” and the area around the bump doesn’t get covered with lubricating tears.