In a conversation with Dr. Parag Majmudar, Dr. Terry O'Brien discusses current issues in ocular microbiology. Toxic Anterior Segment Syndrome (TASS) causation and differential diagnosis vs. endophthalmitis. Residual debris or viscoelastic on surgical instruments can cause an inflammatory reaction which can resemble endophthalmitis. Early endophthalmitis is different from TASS in several key measures: often with TASS there is no pain, non-reactive pupil, elevation of IOP, and blurred vision in association with significant corneal edema beyond what one would normally expect with phacoemulsification. Combating TASS is simple. Clean surgical instruments sufficiently. An option is to increase the inventory of surgical instruments in your surgery center. This allows staff ample time to prepare instruments. Recent epidemic fungal keratitis cases in contact lens wearers have involved Fusarium oxysporum and solani. The contact lens case, the solution, and the lenses themselves, need to be viewed as a mini-ecosystem. Acanthamoeba keratitis also on the rise in contact lens patients. The popularity of class 4 silicone hydrogel lenses that are stiffer materials may lead to micro-trauma of the epithelium, then the biocides that are taken up by the material are released onto the ocular surface creating punctate keratopathies which may open the door to Acanthamoeba and other non-bacterial pathogens. Switching to daily-ware disposable lenses, though costly, would provide one solution to some of these infections.