What are the appropriate uses of a fluorine examination with a wood lamp and obtaining visual acuity in a patient suspected of having a foreign body in the eye?

Appropriate Use of Fluorescein Examination and Visual Acuity Testing for Suspected Eye Foreign Body

Fluorescein examination with a wood lamp is essential for detecting corneal injuries and foreign bodies in the eye, while obtaining visual acuity is necessary to establish baseline vision and assess the extent of injury. 1, 2

Fluorescein Examination

• Fluorescein staining is indicated for disclosing corneal injury when a foreign body is suspected, as it can reveal epithelial defects and linear scratch marks that may not be visible on standard examination 1, 2
• Particularly valuable for detecting transparent or embedded foreign bodies that may be missed during routine examination 2
• Can help identify foreign bodies embedded in the upper palpebral conjunctiva that cause corneal abrasions but remain hidden during standard slit lamp examination 2
• FDA-approved for staining the anterior segment of the eye to disclose corneal injury 1

Visual Acuity Testing

• Essential as a baseline measurement before any intervention to assess the extent of injury and monitor treatment outcomes 3
• Should be performed under standard ophthalmic lighting conditions, with and without correction 4
• Pinhole testing should be done to assess best-corrected visual potential 4
• Comparison of visual acuity measurement with functional status helps determine the impact of the foreign body 4

Combined Approach for Suspected Foreign Body

• Begin with visual acuity testing to establish baseline vision 4, 3
• Follow with fluorescein examination to identify corneal epithelial defects and locate potential foreign bodies 1, 2
• For radiopaque foreign bodies (metal, glass, stone), radiographs have approximately 98% sensitivity 4
• For radiolucent foreign bodies (wood, plastic), ultrasound is the imaging modality of choice with 90% sensitivity 4

Important Considerations

• Foreign body sensation without visible foreign body on standard examination warrants fluorescein staining to detect subtle corneal injuries 2, 5
• Patients with persistent foreign body sensation despite initial negative findings should undergo repeat fluorescein examination 5
• High-velocity eye injuries or penetrating trauma require immediate medical attention beyond just fluorescein examination 6, 3
• Contact lens-related foreign body sensation requires immediate medical attention, including removal of the contact lens 6

Clinical Pitfalls to Avoid

• Relying solely on standard examination without fluorescein staining may miss transparent or embedded foreign bodies 2, 5
• Failing to obtain baseline visual acuity can make it difficult to assess progression or improvement 4, 3
• Misdiagnosing as simple conjunctivitis without ruling out foreign body with fluorescein staining 2
• Overlooking foreign bodies in the upper palpebral conjunctiva, which require eversion of the eyelid for proper examination 2