If rupture risk exists, which sampling method should be avoided for corneal cytology?

• A. Blade stub scraping
• B. Cytobrush
• C. Swab
• D. Impression smear

Answer: (C)

When rupture risk exists, the goal is to obtain diagnostic cells with the least possible trauma to the cornea. A swab requires rubbing or pressing the surface to collect cells, which creates shear forces and can abrade a fragile corneal epithelium. This mechanical irritation increases the chance of worsening a thinning area or causing perforation. Other methods involve different contact patterns, but the key point is to minimize surface manipulation in a cornea at risk, making the swab the least desirable choice in this scenario. Prefer gentler approaches that lift cells with minimal friction, such as impression-based techniques, when rupture risk is present.