Anterior chamber contamination after uncomplicated phacoemulsification and intraocular lens implantation

PURPOSE: To determine the frequency of anterior chamber contamination occurring during uncomplicated cataract surgery with intraocular lens implantation using phacoemulsification through a scleral tunnel incision. METHODS: In a prospective study, anterior chamber aspirates of one eye each of 103 consecutive ambulatory patients who underwent uncomplicated cataract surgery with lens implantation were cultured. The anterior chamber aspirate was withdrawn immediately upon the completion of surgery. Conjunctival cultures of the same eye were taken immediately before surgery, after the eye and periocular area had been prepared and draped. Multiple use topical medications used preoperatively on all patients were cultured at the end of the surgical day. RESULTS: Intraocular aspirates yielded positive cultures in five specimens (5%), four of which were identified as Staphylococcus epidermidis. Quantification disclosed colony counts ranging between 100 and 200 colony forming units per milliliter. Results of conjunctival cultures were positive in ten specimens (10%). Staphylococcus epidermidis was the most common isolate, identified in seven of the ten positive cultures. Positive intraocular and conjunctival culture results were not present concurrently in any patient. Microorganisms were recovered from the multiple use topical medications on nine of the 26 successive surgical days. Neisseria species was the most frequent isolate (7, 44%), followed by S. epidermidis (5, 31%). The frequency of contamination of the anterior chamber was independent of wound width (χ² = 0.869) and operative time (χ² = 4.77). CONCLUSION: Bacterial contamination of the anterior chamber was detected in five (5%) of the patients. This reduced incidence of contamination compared with that of previous studies may be related to the preoperative preparation, the surgical technique, or both. Contamination of the multiple use topical medications and bulbar conjunctiva define possible sources of pathogens that may enter the anterior chamber. The absence of any clinical ocular infection in all patients attests to the small inoculum sizes, as well as the ability of the anterior chamber to clear small bacterial loads.