Seidel Test

From EyeWiki


History

The Seidel test is named after the German ophthalmologist Erich Seidel (1882-1948).

Definition

The test is used to reveal leaks from the cornea, sclera, or conjunctiva following injury or surgery.

Principle

Aqueous in the anterior chamber is a clear fluid. The tear film covering the ocular surface is also a transparent layer. Following ocular injury or surgery, if a leak is present then this transparent fluid will leak out of the eye and mix with the also transparent tear film, preventing identification of the leak. Thus, if the dye were injected into aqueous then the site of leak can be identified by the dye leaking out of the wound. However this is an invasive procedure, so a non-invasive alternative approach is the Seidel test. The principle of the Seidel test is to apply a dye to the ocular surface so that any aqueous leak encompassed by the dye will dilute it, allowing the leak to become more obvious by the color change.

Dye used in seidel test

Fluorescein 10% (Resorcinolphthalein) is used in the Seidel test. Fluorescein is a synthetic organic compound that is dark orange or red in color. It can be prepared from phthalic anhydride and resorcinol in the presence of zinc chloride via the Friedel-Crafts reaction. As concentrated fluorescein does not actually fluoresce, it is used in relatively dilute concentrations in most circumstances. Concentrated fluorescein will be diluted by a leak, and on slit lamp examination with cobalt blue light this leak will appear bright green.

Strip.jpg

Technique

  • Explain the procedure to the patient
  • Clean off the slit lamp and position the patient
  • Gently apply a topical anesthetic eye drop
  • Using a cotton tipped applicator, carefully dry the area of the suspected leak
  • Carefully apply a moistened fluorescein strip to the area of the suspected leak, "painting" on the dye. Alternatively, the dye can be applied to the superior conjunctiva, allowing the dye to flow down over the cornea
  • Visualize the injured site under a cobalt blue light source and evaluate for a green flow (positive Seidel test)
  • Estimate the rate and volume of fluid exiting the wound

Indications

  1. To identify the site of ocular leak after globe injury
  2. To identify whether a corneal laceration is sealed or not
  3. To evaluate different sutureless cataract incision configurations
  4. Post-operatively to ensure appropriate wound closure

Contraindications

  1. Obvious globe rupture (corneal perforation or full thickness eye laceration)
  2. Hypersensitivity to fluorescein

Precautions

  • Do not apply pressure to eye during test (risk of tissue extrusion)

Requirements

  1. Slit lamp with cobalt blue light source
  2. Fluorescein strip
  3. Topical anesthetic eye drops

Management

  • A full thickness penetration (leaking wound) should be treated as an emergency and requires prompt surgical repair. Care must be taken to protect the eye.
  • A sealed corneal laceration is treated by applying a bandage contact lens or pressure patching, along with antibiotic drops.
  • Any inadequate wound closure or incision closure needs to be reviewed. Cyanoacrylate glue and a bandage contact lens may be applied to close the wound.
  • Broad-spectrum antibiotics are indicated to decrease any chance of microbial keratitis or endophthalmitis.
  • Tetanus prophylaxis is given.

Prognosis

Depends on the injuries sustained and the extent of damage at presentation.

Additional Resources

References

  1. Cain W, Sinskey RM. Detection of anterior chamber leakage with Seidel's test. Arch Ophthalmology. 1981 Nov; 99(11): 2013.