Fluorescein Sodium Eye Strips: Clinical Uses, Procedure & Diagnostic Guide

What Are Fluorescein Sodium Ophthalmic Strips?

Fluorescein sodium (NaFl) ophthalmic strips are single-use diagnostic strips impregnated with fluorescein dye — a water-soluble, non-toxic compound that fluoresces bright yellow-green under cobalt blue light. Each strip contains 1 mg of fluorescein sodium USP, making them the standard tool for a wide range of ocular surface assessments.

SciMed's fluorescein sodium strips carry a 2030 expiry date and are supplied in packs of 100, individually wrapped to maintain sterility and consistency.

Clinical Applications

Fluorescein strips are indispensable across optometry, ophthalmology, and emergency eye care settings:

1. Corneal Abrasion & Foreign Body Detection

Fluorescein stains disrupted corneal epithelium bright green under cobalt blue illumination. Any breach in the epithelial surface — from an abrasion, laceration, or embedded foreign body — becomes immediately visible. This is often the first diagnostic step in any acute eye injury presentation.

2. Applanation Tonometry (IOP Measurement)

In Goldmann applanation tonometry, fluorescein is instilled prior to the measurement to create the characteristic blue-green semicircles used to determine intraocular pressure (IOP). Accurate IOP measurement is fundamental in glaucoma screening and management. Fluorescein strips provide a convenient, sterile, and consistent dose for this procedure.

3. Tear Break-Up Time (TBUT)

The TBUT test assesses tear film stability by measuring the time (in seconds) between a full blink and the first appearance of a dry spot in the fluorescein-stained tear film. A TBUT of less than 10 seconds is generally considered abnormal and suggests dry eye disease. Fluorescein strips deliver a controlled amount of dye ideal for this assessment.

4. Contact Lens Fitting

When fitting rigid gas-permeable (RGP) contact lenses, fluorescein patterns reveal the relationship between the lens and the cornea. The pattern of dye pooling and clearance helps clinicians assess alignment, central fit, edge lift, and bearing areas, enabling precise lens customisation.

5. Punctal Patency & Lacrimal Assessment

Fluorescein can be used to evaluate nasolacrimal drainage patency. Following instillation, the presence or absence of dye in nasal secretions (Jones Test) helps diagnose obstruction of the lacrimal drainage system.

6. Wound Leakage Detection (Seidel Test)

The Seidel test uses fluorescein to detect aqueous humour leakage from corneal wounds or surgical incisions. Leaking aqueous dilutes and streams the concentrated dye, producing a distinctive darkened rivulet pattern — a critical finding in any post-surgical or trauma assessment.

How to Use Fluorescein Sodium Strips

  1. Wash hands and open the sterile packaging
  2. Lightly moisten the tip of the strip with a drop of sterile saline or the patient’s own tears — do not over-saturate
  3. Gently touch the moistened tip to the lower conjunctival fornix (lower inner eyelid) — avoid direct contact with the cornea
  4. Ask the patient to blink once or twice to distribute the dye across the ocular surface
  5. Examine under cobalt blue light using a slit lamp or Burton lamp
  6. Discard the strip after single use — never reuse

Tip: For TBUT testing, use a minimal amount of fluorescein. Excess dye can shorten the apparent TBUT by diluting the tear film.

Storage & Handling

  • Store at room temperature, away from direct sunlight and humidity
  • SciMed fluorescein strips are individually foil-wrapped to maintain sterility until the point of use
  • Do not use if the packaging is damaged or if the strip discolouration appears inconsistent
  • Expiry: Each strip is clearly dated; SciMed's current stock carries a 2030 expiry

Safety & Contraindications

Fluorescein sodium is well-tolerated and considered safe for routine clinical use. However, note:

  • Soft contact lenses absorb fluorescein and will be stained permanently — always remove soft lenses before instillation
  • Fluorescein may temporarily discolour the tear film and periocular skin — this is transient and harmless
  • Rare allergic reactions have been reported; exercise caution in patients with known hypersensitivity

Shop Fluorescein Sodium Strips at SciMed

SciMed supplies 1mg fluorescein sodium NaFl ophthalmic strips in packs of 100, individually wrapped, with a 2030 expiry date. Trusted by optometrists, ophthalmologists, and emergency departments across the US.

Shop Fluorescein Sodium Strips (Pack of 100) →

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