Does the sampling instrument influence corneal culture outcome in patients with infectious keratitis? A retrospective study comparing cotton tipped applicator with knife blade.

Corneal sampling by cotton tipped applicator generated a higher rate of positive corneal cultures and a higher proportion of isolated microbes than by knife blade. Future studies with randomised sampling order are needed to establish which instrument, cotton tipped applicator or knife blade, is the most effective in sampling microbes for direct inoculation in patients with infectious keratitis.