Which test can serve as an adjunctive diagnostic aid for infectious keratitis?

• A. Tear-film cytology
• B. Schirmer tear test
• C. Intraocular pressure measurement
• D. Anterior chamber paracentesis

Answer: (A)

Infectious keratitis requires rapid identification of the causative organisms to guide treatment, and tests that sample the corneal surface or tear film can provide direct clues about what is causing the infection. Tear-film cytology collects material from the tear film or superficial corneal surface and uses staining techniques to visualize organisms such as bacteria, fungi, or protozoa (for example, Acanthamoeba). This approach can reveal pathogens quickly and with minimal invasiveness, helping tailor therapy while awaiting culture results. The other options don’t fit as adjunct diagnostic aids for corneal infection: the Schirmer tear test measures tear production and is more about tear-film deficiency than infection; intraocular pressure measurement assesses glaucoma risk and has no direct diagnostic value for the infected cornea; anterior chamber paracentesis is an invasive procedure aimed at suspected intraocular involvement (endophthalmitis) rather than a routine adjunct for keratitis.