Fluorescein strips are diagnostic tools used in eye examinations. They help healthcare professionals identify and visualize various conditions affecting the eye’s surface that might otherwise be invisible.
Understanding Fluorescein Strips
Fluorescein strips consist of sterile paper impregnated with fluorescein sodium dye, which exhibits a highly fluorescent property. When applied, this dye selectively stains areas of cellular loss or damage on the corneal epithelium, the outermost layer of the eye, but does not stain healthy, intact corneal cells. Healthcare professionals primarily use these strips to reveal corneal abrasions, detect foreign bodies, assess tear film abnormalities, and evaluate contact lens fit. The dye absorbs blue light and then emits a yellow-green light, a phenomenon known as fluorescence. This fluorescence becomes visible when the eye is illuminated with a cobalt blue light, allowing practitioners to observe and diagnose conditions affecting the ocular surface.
Step-by-Step Application Guide
Begin by preparing the patient and the strip. Explain the procedure to the patient to ensure their comfort and cooperation, and ensure any contact lenses are removed, as fluorescein can permanently stain soft contact lenses. Moisten the impregnated tip with one or two drops of sterile saline solution or a topical anesthetic. This ensures full fluorescence and patient comfort upon application.
Gently retract the patient’s lower eyelid, exposing the palpebral conjunctiva. Carefully touch the moistened tip to the lower conjunctival sac for 3 to 5 seconds, avoiding forceful contact with the cornea or conjunctiva to prevent abrasion. After applying the dye, instruct the patient to blink several times to distribute it evenly. Using minimal solution helps prevent over-illumination of the tear film, which can obscure small lesions.
What to Look For After Application
After the fluorescein dye has been applied and distributed, examine the eye using a cobalt blue light, often from a Wood’s lamp or a slit lamp. This light makes any damaged areas on the ocular surface appear brightly fluorescent yellow or green, highlighting compromised areas of the cornea or conjunctiva. A normal eye, with an intact corneal epithelium, will show a uniform, diffuse green glow from the tear film, without distinct areas of intense staining. In contrast, corneal abrasions or defects appear as bright green or yellow-green areas, indicating the injury’s location and extent, while foreign bodies may present as dark spots surrounded by staining. Interpreting these patterns requires professional medical judgment to accurately diagnose the condition and determine the appropriate course of action.
Important Safety and Disposal Tips
Fluorescein strips are for single-use only, particularly between eyes, to prevent infection transmission. Always use sterile strips from individually sealed packages, ensuring the dye part does not contact fingers to maintain sterility. Fluorescein sodium ophthalmic strips are generally considered non-toxic and non-irritating with few side effects, though some individuals may experience temporary stinging, irritation, or blurred vision. Allergic reactions are rare but can occur, manifesting as rash, hives, or swelling. If any adverse reactions, vision changes, or irritation persist, immediate consultation with a healthcare professional is necessary.
After use, dispose of fluorescein strips as medical waste in designated clinical waste containers. Proper disposal helps prevent potential biohazards and ensures compliance with waste management regulations.