Fluorescein Dye Use in Corneal Tear Inspection
Fluorescein dye is primarily used to identify and assess corneal epithelial disruptions by staining areas where intercellular junctions are compromised, allowing visualization of corneal tears or injuries when examined with a cobalt blue filter. 1, 2
Primary Applications of Fluorescein Dye
- Corneal epithelial defect visualization: Fluorescein stains areas of the corneal epithelium where intercellular junctions are disrupted, allowing the dye to permeate into the tissue and highlight injuries 1
- Contact lens fitting: Helps evaluate the fit of contact lenses by revealing areas of excessive pressure or inadequate tear exchange 2
- Applanation tonometry: Used during intraocular pressure measurement with Goldmann tonometry 2, 3
- Tear film stability assessment: Used in tear break-up time (TBUT) testing to evaluate the stability of the precorneal tear film 1
Proper Technique for Fluorescein Application
- Apply fluorescein using a saline-moistened strip to the inferior tarsal conjunctiva 1
- Avoid fluorescein-anesthetic combination drops as anesthetics may affect test results 1
- After instillation, examine the ocular surface through a biomicroscope using a cobalt blue filter 1
- For optimal visualization of corneal staining, wait approximately 2 minutes after application 1
- Enhanced visibility can be achieved by using a yellow filter in conjunction with the cobalt blue light 1
Interpretation of Fluorescein Staining Patterns
- Normal eyes: May show mild fluorescein staining, particularly in the morning 1
- Dry eye: Typically presents with exposure-zone punctate or blotchy fluorescein staining 1
- Viral keratoconjunctivitis: Often shows diffuse corneal and conjunctival staining 1
- Staphylococcal blepharitis/MGD: Typically shows staining of the inferior cornea and bulbar conjunctiva 1
- Superior limbic keratoconjunctivitis: Characterized by staining of the superior bulbar conjunctiva 1
- Aqueous tear deficiency: Shows exposure-zone (interpalpebral) corneal and bulbar conjunctival staining 1
Advantages of Fluorescein Over Other Dyes
- Fluorescein is more easily visualized on the cornea than on the conjunctiva 1
- Causes less ocular irritation compared to rose bengal dye 1
- Does not impede corneal epithelial wound healing, unlike some other stains 4
- Can be used for multiple diagnostic purposes (tear film assessment, corneal injury detection, tonometry) 2
Important Considerations and Precautions
- Fluorescein staining should be performed before instillation of any other eyedrops 1
- Avoid manipulating eyelids before evaluation to prevent false results 1
- Fluorescein can temporarily increase measured corneal thickness by approximately 46.6 μm, which may affect corneal measurements for refractive surgery planning 3
- Staining may become more apparent after about 2 minutes and is more intense when observed with a yellow filter 1
- Recurrent tear break-up in the same area may indicate localized anterior basement-membrane abnormalities 1