What are the key components to describe when characterizing a corneal keratitis lesion?

Describing a Corneal Keratitis Lesion

When documenting a corneal keratitis lesion, systematically describe the stromal infiltrate characteristics (location, size, depth, margins, color), epithelial defect, surrounding stromal changes, and anterior chamber reaction using slit-lamp biomicroscopy with fluorescein staining. 1

Essential Components of Lesion Description

Stromal Infiltrate Characteristics

The infiltrate itself requires detailed characterization across multiple dimensions:

• Location: Document whether the infiltrate is central (within 3 mm of corneal center), peripheral, inferior, perineural, or associated with surgical/traumatic wounds 1
• Size: Measure and record dimensions in millimeters—infiltrates ≥2 mm are considered large and clinically significant 1
• Depth: Specify whether involvement is superficial, mid-stromal, or extends to the posterior one-third of stroma (deeper lesions carry worse prognosis) 1
• Density: Characterize the opacity as light, moderate, or dense 1
• Shape: Note if the infiltrate has distinctive patterns such as ring-shaped or irregular configuration 1
• Number: Document single versus multiple infiltrates, and identify any satellite lesions 1

Infiltrate Margin Characteristics

The character of the infiltrate edges provides critical diagnostic information:

• Margin definition: Bacterial keratitis typically presents with indistinct, feathery edges versus well-demarcated borders 1
• Suppuration: Note presence of purulent material suggesting active bacterial infection 1
• Necrosis: Document any tissue necrosis at the margins 1
• Crystalline appearance: May suggest certain organisms or chronic infection 1
• Color: Record the color of the infiltrate (white, yellow, gray) 1

Epithelial Assessment

• Epithelial defect: An epithelial defect is typically present in bacterial keratitis and should be documented with fluorescein staining 1
• Defect size and shape: Measure the epithelial defect dimensions separately from the infiltrate 1
• Punctate keratopathy: Note any surrounding punctate epithelial changes 1
• Epithelial edema: Document presence and extent 1

Critical distinction: Differentiate true epithelial staining from pooling of fluorescein in areas of corneal thinning with intact epithelium—pooling can be wicked away with a cotton swab or irrigation 1

Surrounding Stromal Changes

• Stromal edema: Document edema and white cell infiltration in surrounding stroma, which are characteristic features of bacterial keratitis 1
• Stromal thinning: Measure and document any thinning, as this indicates tissue loss and perforation risk 1
• Stromal melting: Note presence of active tissue destruction 1
• Perforation: Document if present—this is a surgical emergency 1
• Neovascularization: Record any corneal vessels and their extent 1

Anterior Chamber Evaluation

• Anterior chamber reaction: Bacterial keratitis is often accompanied by anterior chamber inflammation 1
• Cell and flare: Grade the degree of inflammation 1
• Hypopyon: Document presence, height in millimeters, and position (may present as blunting of inferior angle or at 3:00/9:00 if patient was recently supine) 1
• Fibrin: Note any fibrin formation 1
• Hyphema: Document if blood is present 1

Additional Corneal Features

• Endothelial plaque: Look for endothelial involvement 1
• Foreign body: Document any foreign material including sutures 1
• Previous scarring: Note evidence of prior corneal inflammation (thinning, scarring, neovascularization) 1
• Surgical history: Document signs of previous corneal or refractive surgery 1

Anterior Vitreous Assessment

• Examine for presence of inflammation, which may indicate more severe infection 1

Clinical Context for Documentation

Bacterial keratitis typically presents with suppurative stromal infiltrates (particularly >1 mm) with indistinct edges, surrounding stromal edema and white cell infiltration, an epithelial defect, and anterior chamber reaction. 1

Common Pitfalls to Avoid

• Do not confuse fluorescein pooling in areas of thinning with true epithelial defects—test by wicking away or irrigating 1
• Central infiltrates within 3 mm of the corneal center and ≥2 mm in size require cultures before initiating therapy 1
• Presence of hypopyon indicates 2.28 times increased odds of perforation or need for therapeutic keratoplasty 2
• Infiltrates involving the posterior one-third of stroma carry 71.4% risk of perforation or need for keratoplasty 2

Documentation for Risk Stratification

Certain features mandate more aggressive management:

• Large central infiltrates: ≥2 mm within 3 mm of corneal center 1
• Multiple infiltrates: Presence of ≥2 adjacent lesions 1
• Significant stromal involvement: Deep infiltrates or stromal melting 1
• Anterior chamber cells: ≥1+ cells present 1
• Post-surgical: History of corneal surgery 1

These features require corneal cultures and smears before initiating antimicrobial therapy 1