Which dye is used to stain dead or degenerating cells and mucus and is helpful for keratomycosis and punctate keratitis?

• A. Fluorescein
• B. Rose Bengal
• C. Lissamine green
• D. Methylene blue

Answer: (B)

Rose Bengal works because it stains dead or degenerating epithelial cells and mucus on the corneal surface. This highlights areas of epithelial damage and mucus accumulation, making it especially useful when examining keratomycosis (fungal keratitis) and punctate keratitis, where irregular, damaged epithelium and mucus are common findings. Fluorescein, by contrast, marks epithelial defects where the surface integrity is lost but does not stain mucus or dead cells. Lissamine green also stains devitalized cells and mucus, but it is more commonly used for dry eye and conjunctival staining, not specifically for keratitis. Methylene blue has other uses and is not the standard choice for highlighting fungal keratitis or punctate corneal lesions. Therefore, the dye that best fits staining dead or degenerating cells and mucus and aiding diagnosis of keratomycosis and punctate keratitis is Rose Bengal.