True or false: Serious corneal disease can be present without positive stain uptake.

• A. True
• B. False
• C. Not determinable
• D. Only with prior antibiotic use

Answer: (A)

Fluorescein staining detects breaks in the corneal epithelium, so uptake occurs where the surface is breached. But serious corneal disease can be present even if the stain is negative because pathology may lie deeper in the stroma or endothelium while the epithelial layer remains intact. In such cases the dye cannot access those deeper layers, so no uptake is seen despite significant disease. This is why a normal fluorescein exam does not completely rule out serious keratopathy; signs like stromal edema, deep infiltrates, or endothelial dysfunction may reveal pathology that requires further assessment and management beyond staining results. If suspicion remains, use additional evaluation and adjunct dyes (like rose bengal or lissamine green) and correlate with clinical signs and, if needed, imaging or culture to guide treatment.