Epithelial Pooling vs Staining in Dense Central Band Keratopathy

Sometimes it can be difficult to tell the difference between a true epithelial defect versus fluorescein pooling, especially in an eye with dense central band keratopathy.  Fluorescein should not stain intact corneal epithelium. However, in areas of stromal loss or fibrosis, fluorescein can "pool," that is, it can fill the potential space and gives the false impression of true staining.


Here are images of a patient with central band keratopathy with three discrete areas of what appear  to be staining centrally that on first look appeared to be epithelial defects, but are clearly pooling with intact epithelium when viewed with OCT.


A red/ green shift in AS-OCT implies a shift in density.  It is not correlated with a pathological change as in the RNFL reading (green normal, red thin), but rather meant to optically distinguish the layers.

The red in this image highlights the area of band keratopathy and accompanying subepithelial fibrosis and sub-Bowman's anterior stromal haze. There is a remarkable change in density in the anterior stroma

In certain patient's with band keratopathy, Bowman's layer can be eroded. However, the destruction of Bowman's layer varies in patient to patient. The black areas above the red under the intact epithelium represent an optical "shadow" behind an area of extreme density like calcium.

Remember, if AS-OCT is not available to you, one clinical exam trick is to use a sterile cotton swab or weck-cel sponge to wick the excess pooling to either demonstrate intact epithelium or true staining below. In this case, upon wicking away the pooled fluorescein, the epithelium was clinically confirmed to be intact.

Images courtesy of Brett Levinson, MD of Specialized Eye Care.