How does foreign body tracking appear?

How does foreign body tracking appear?

• A. Linear superficial corneal epithelial staining; tracking due to lens movement with blink
• B. Subconjunctival hemorrhage
• C. Posterior capsule opacification
• D. Elevated intraocular pressure

Answer: (A)

Tracking of a foreign body shows up as a linear, shallow line of fluorescein staining across the corneal epithelium that follows the direction of blinking. It happens when a small foreign object or a rough edge of the contact lens drags across the surface, causing repetitive mechanical microtrauma each time the lid moves. The stain appears as a straight track and can shift with lens position, reflecting the path traced by the moving object. This pattern is different from subconjunctival hemorrhage, which appears as a localized red patch on the sclera; posterior capsule opacification, which affects vision after cataract surgery; and elevated intraocular pressure, which would not produce a linear corneal staining track.

Tracking of a foreign body shows up as a linear, shallow line of fluorescein staining across the corneal epithelium that follows the direction of blinking. It happens when a small foreign object or a rough edge of the contact lens drags across the surface, causing repetitive mechanical microtrauma each time the lid moves. The stain appears as a straight track and can shift with lens position, reflecting the path traced by the moving object. This pattern is different from subconjunctival hemorrhage, which appears as a localized red patch on the sclera; posterior capsule opacification, which affects vision after cataract surgery; and elevated intraocular pressure, which would not produce a linear corneal staining track.