Fluorescein stain is used to confirm or deny the presence of a corneal ulcer.
For more on corneal ulcers, click here.
Fluorescein stain is a standard formulation according to the U. S. Pharmacopeia. It is available as a solution or paper strips impregnated with stain. When fluorescein strips are used they are first moistened with ocular irrigating solution. Care must be taken to avoid lacerating the cornea with a “paper cut,” thus iatrogenically inducing a corneal ulcer.
While some ulcers can be seen with the naked eye or with magnification, one cannot tell whether the outermost layer of the corneal epithelium is damaged without staining it. It is this layer that is of unique conformation and “seals” the multiple-layer, onion-skin-like cornea from infiltration and dehydration.
It is important to know if the corneal epithelium is damaged because certain medications may lead to blindness in that circumstance. It’s one more reason not to use leftover medication or other patients’ medications.
Even the slightest interruption of the outermost layer of the cornea will become evident when fluorescein stain is applied. Tiny ulcers might need illumination by ultraviolet or “black” light to become apparent.
Fluorescein stain is a sight-saving tool used by general practitioners and board-certified ophthalmologists alike.
See you tomorrow, Dr. Randolph.