Fluorescein Stain

To apply a fluorescein stain to the eye you need a fluorescein strip and a solution, such as a saline flush, sterile water, or an anesthetic eye drop. If you’re staining both eyes, use a second strip if concerned about contamination. 

Apply a couple of drops to saturate the strip. Ideally, you want a drop of fluid right at the tip of the strip. Retract the lower lid and apply the fluorescein along the inside of the eyelid (which is the bulbar conjunctiva) rather than applying it directly to the cornea. Have the patient blink to disperse the stain. The fluorescein will fluoresce under cobalt blue or UV light if there is a corneal injury.

Fluorescein will permanently stain contact lenses, so those should be removed in advance. It will also stain clothes, so hand the patient a tissue to blot tears. Fluorescein uptake is best seen using a slit lamp with cobalt blue light.

A technique I’m not a fan of, and I do not recommend, is fluorescein in a saline flush. I’ve seen many residents put the fluorescein strip into the full flush, which is very dilute. When you replace the plunger and remove the cap it drips out and makes a mess. And if you try to deliver a small volume, it can come out under pressure and explode. A flush is not meant to deliver a single drop at a time. 

Peer Reviewed by Scott Kobner, MD, and Anand Swaminathan, MD.