What is the expected examination finding in a patient with eye pain, redness, and blurry vision after a foreign body entered their eye, with pain relief from tetracaine (anesthetic) drops?

Expected Examination Finding: Area of Fluorescein Uptake

The expected examination finding in this patient is an area of fluorescein uptake on the corneal surface, consistent with a corneal abrasion from foreign body trauma. 1, 2

Clinical Reasoning

This patient's presentation is classic for a corneal abrasion rather than bacterial keratitis, anterior uveitis, or acute angle-closure glaucoma:

Key Diagnostic Features Supporting Corneal Abrasion

• Pain relief with tetracaine (topical anesthetic) is the most discriminating feature—this strongly suggests a superficial corneal epithelial injury rather than deeper pathology 3, 4, 5
• Acute onset after foreign body entry with immediate symptoms points to traumatic epithelial disruption 1
• Normal pupil size and reactivity effectively rules out acute angle-closure glaucoma (which would show a mid-dilated, non-reactive pupil) 1
• Mild conjunctival injection and tearing are consistent with corneal surface irritation but not the severe inflammation seen in bacterial keratitis 6, 1

Why Other Findings Are NOT Expected

Cell and flare on slit lamp examination would indicate anterior chamber inflammation (anterior uveitis), which:

• Does not respond to topical anesthetics 2
• Typically presents with deeper, aching pain rather than sharp foreign body sensation 2
• Would show more pronounced photophobia and ciliary flush 6

Elevated intraocular pressure suggests acute angle-closure glaucoma, which:

• Presents with severe pain, nausea, vomiting, and halos around lights 6
• Shows a mid-dilated, non-reactive pupil (not present in this patient) 1
• Does not respond to topical anesthetics 3

Anterior chamber exudate (hypopyon) indicates severe bacterial keratitis with:

• Suppurative stromal infiltrates >1 mm with indistinct edges 6, 2
• Progressive worsening over hours to days, not immediate onset 6
• Pain that persists despite topical anesthetics 2

Expected Fluorescein Examination Findings

Fluorescein staining will reveal:

• Epithelial defect with fluorescein uptake in the area of foreign body contact 6, 1
• The defect appears bright green under cobalt blue light on slit lamp examination 6
• Pattern may be linear (from foreign body scratch) or geographic depending on mechanism 1
• No stromal infiltrates should be present (which would suggest bacterial keratitis) 6, 2

Critical Examination Technique

• Apply fluorescein using a saline-moistened strip to the inferior tarsal conjunctiva 6
• Examine with cobalt blue filter on slit lamp (or portable device if slit lamp unavailable) 6, 7
• Distinguish true epithelial staining from pooling in areas of corneal thinning—pooling can be wicked away with irrigation 1
• Staining becomes more apparent after approximately 2 minutes 6

Important Clinical Pitfalls

Do not assume absence of bacterial keratitis based on pain relief alone:

• While pain relief with tetracaine strongly suggests simple abrasion, bacterial keratitis can develop at sites of epithelial defects 6, 2
• Stromal infiltrates are the key distinguishing feature between simple abrasion and bacterial keratitis 2
• Contact lens wear significantly increases risk of bacterial keratitis, even with traumatic abrasion 6, 2

Avoid prolonged tetracaine use:

• While short-term use (24 hours) is safe and effective for pain control 4, 5, prolonged use causes permanent corneal opacification and ulceration 3
• Patients must be counseled that the eye will be insensitive for 10-20 minutes after use, risking further injury 3

Ensure proper follow-up:

• Re-examination at 24-48 hours is essential to confirm healing and rule out developing infection 2
• Any persistent symptoms, worsening pain, or development of stromal infiltrates requires immediate ophthalmology consultation 6, 2