When should culture be performed during an ocular exam?

• A. After applying proparacaine
• B. Before proparacaine with swab focused on lesion
• C. After fluorescein staining
• D. Only when bacterial infection is suspected

Answer: (B)

Sampling for culture should be done before any topical meds are applied and directed to the lesion itself. Collecting prior to proparacaine preserves the true microbial population on the ocular surface and avoids any potential alteration or washout of organisms that can occur after anesthesia. Swabbing the lesion focuses on the area most likely to harbor the causative pathogen, increasing the chance of identifying what's driving the infection rather than picking up normal conjunctival flora. Fluorescein staining or applying anesthetic afterward can contaminate or obscure the sample, and culturing isn’t limited to cases where bacterial infection is already suspected—cultures help identify bacteria, fungi, and other pathogens in infectious ocular processes to guide appropriate treatment.