_____ stain is the most commonly used dye for detecting corneal epithelial defects.

Fluorescein stain is the most commonly used dye for detecting corneal epithelial defects due to its unique properties that make it particularly suitable for this purpose. When fluorescein stain is applied to the eye, it binds to areas where the corneal epithelium is compromised, allowing practitioners to visualize these defects clearly. The dye fluoresces brightly under blue light, which makes it easy to identify and assess the size and depth of corneal injuries or abrasions.

In contrast, while other stains like indocyanine, methylene blue, and rose Bengal have their uses, they are not the first choice for detecting corneal epithelial defects. Indocyanine is primarily used in ocular angiography to evaluate blood flow in the retina and choroid, methylene blue can be used in various diagnostic procedures but does not provide the same clarity for corneal issues, and rose Bengal is typically utilized for assessing dry eye conditions and identifying cell damage but not specifically for initial corneal defect detection. Therefore, fluorescein’s effectiveness in highlighting corneal epithelial defects establishes it as the preferred option.