Seidel Test

From EyeWiki



History

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

Definition

The test used to reveal ocular leaks from the cornea, sclera or conjunctiva following injury or surgery and sometimes disease is called Seidel test.

Principle

Aqueous in the anterior chamber is a clear fluid. Tear film covering the conjunctiva and cornea is also a transparent layer. Following ocular injury or surgery or any disease, if ocular leak is present then this fluid will leak out of the eye. However due to tear film, this aqueous leak disappears and site of the leak cannot be identified. 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 non-invasive alternative would obviously be preferable and an alternative approach is the seidel test – dye the tear film. Any aqueous leak will dilute the dyed tears in the site of leak and the leak would be much more obvious by color change.

Dye used in seidel test

Fluorescein 10 % (Resorcinolphthalein) dye is used in the seidel test. Fluorescein is a synthetic organic compound available as a 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 the leak which will flow downward due to gravity and on slit lamp examination by using cobalt blue light this leak will appear bright green.

Strip.jpg

Technique

  • Prepare the slit lamp
  • Explain the procedure to the patient
  • Gently apply the topical anesthetic eye drop
  • Carefully apply moistened Fluorescein dye strip to the superior conjunctiva.


(In corneal tear, the dye can usually be applied to the superior conjunctiva, allowing the dye to flow down over the cornea. Another advantage of applying fluorescein to the superior conjunctiva above the suspected lesion is that Bell’s phenomenon whereby the eyes rotate upward and outward.)

  • Ask patient to blink once
  • Visualize the injured site under cobalt blue light source
  • Estimate the rate and volume of fluid exiting the wound
  • Apply topical antibiotic eye drop

Indications

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

Contraindications

  1. Obvious Globe rupture
  2. Corneal perforation
  3. Full thickness eye laceration
  4. Hypersensitivity to Fluorescein

Interpretation (positive seidel test)

  1. Fluorescein dye diluted by aqueous fluid
  2. Bright green concentrated dye surrounds leak site (above and to side)

Precautions

  • Do not apply pressure to eye during test (risk of eye 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 require prompt surgical repair. Care must be taken to protect the eye.
  • A sealed corneal tear (small wound) is treated by applying bandage contact lens or pressure patching.
  • 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.

References

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