How do I perform Seidel's test on an eye?

How to Perform Seidel's Test on an Eye

Seidel's test is performed by applying fluorescein dye to the ocular surface and observing for a bright green stream indicating aqueous humor leakage from a corneal or conjunctival wound.

Purpose and Indications

Seidel's test is used to detect leakage of aqueous humor from:

• Suspected corneal perforations or lacerations
• Post-surgical wound leaks
• Traumatic eye injuries
• Suspected bleb leaks after glaucoma filtering surgery

Materials Needed

• Fluorescein strips or sterile fluorescein solution (1-2%)
• Cobalt blue filter on slit lamp
• Cotton-tipped applicator (if using strips)
• Sterile saline (if using strips)

Step-by-Step Technique

1. Patient Positioning:

   • Position the patient at the slit lamp
   • Ensure proper head placement and stability

2. Preparation:

   • If using fluorescein strips, moisten the strip with sterile saline
   • Allow the strip to become adequately saturated (at least one minute for proper concentration)

3. Application Method:

   • Direct application method: Apply the moistened fluorescein strip directly to the suspected leak site
   • Indirect application method: Apply fluorescein to the inferior fornix and ask the patient to blink to distribute the dye

4. Observation:

   • Immediately examine the area of suspected leakage using the cobalt blue filter on the slit lamp
   • Look specifically for a bright green stream or flow emerging from the wound site
   • The aqueous humor dilutes and washes away the fluorescein, creating a characteristic bright green stream against the orange-yellow background of the fluorescein-stained ocular surface

5. Interpretation:

   • Positive Seidel test: Bright green stream flowing from the wound site indicates aqueous humor leakage
   • Negative Seidel test: No streaming or color change at the suspected site

Special Considerations

• For small or intermittent leaks, apply gentle pressure on the globe through the closed eyelid to increase intraocular pressure and potentially reveal the leak
• For suspected bleb leaks, examine the entire bleb surface carefully as leaks may be small and difficult to detect
• Avoid using anesthetic drops before the test as they may contain preservatives that can interfere with fluorescein staining
• Avoid excessive manipulation of the eye in cases of suspected perforation to prevent exacerbating the injury

Pitfalls and Caveats

• False negatives can occur with very small leaks or if the leak is temporarily sealed
• A negative test does not completely rule out a wound leak, especially if the leak is intermittent
• Avoid performing non-contact tonometry in cases of suspected corneal perforation, as the air-jet can disrupt self-sealed wounds and worsen the condition 1
• For optimal visualization, examine the area immediately after dye application, as dilution occurs rapidly with aqueous leakage

Documentation

Document the following in the medical record:

• Location of suspected leak
• Test result (positive or negative)
• Characteristics of any leakage observed
• Any maneuvers performed to elicit the leak (such as gentle pressure)

By following this systematic approach, you can effectively perform Seidel's test to detect aqueous humor leakage from the eye, which is crucial for diagnosing corneal or conjunctival wounds and guiding appropriate management.