Fluorescein stains which structure of the cornea?

Fluorescein stains which structure of the cornea?

• A. Epithelium
• B. Stroma
• C. Descemet's membrane
• D. Endothelium

Answer: (B)

Fluorescein staining reveals where the corneal surface is breached. The epithelium acts as a barrier to the dye, so in a normal cornea you don’t see staining. When there is an epithelial defect, the dye can reach the underlying tissue and stain it. The exposed stromal bed becomes stained, outlining the ulcer under blue light. So, in this context fluorescein highlights the stroma because the epithelial barrier is compromised, exposing the stromal tissue.

Fluorescein staining reveals where the corneal surface is breached. The epithelium acts as a barrier to the dye, so in a normal cornea you don’t see staining. When there is an epithelial defect, the dye can reach the underlying tissue and stain it. The exposed stromal bed becomes stained, outlining the ulcer under blue light. So, in this context fluorescein highlights the stroma because the epithelial barrier is compromised, exposing the stromal tissue.