The effect of preoperative topical antibiotics in cataract surgery

PURPOSE: We studied whether topical antibiotics prevent endophthalmitis after cataract surgery. METHODS: Cefmenoxime hydrochloride (CMX) or artificial tears (AT) were randomly instilled 72 hours before surgery. Conjunctival swab samples were taken before the instillation of eye drops (1) and after the instillation of eye drops (2). Aqueous humor (3) was cultured intraoperatively. RESULTS: Positive cultures were found in the CMX group of eyes in 76.3% of (1) samples, 58.1% of (2) samples, and 6.0% of (3) samples. In the AT group of eyes, positive cultures were found in 78.6% of (1) samples, 63.8% of (2) samples, and 2.9% of (3) samples. CMX was not effective. In the CMX group of eyes, Staphylococcus epidermidis was found in 59 eyes of group (1), 5 eyes of group (2), and 0 eyes of group (3). In the AT group of eyes, S. epidermidis was found in 70 eyes of group (1), 26 eyes of group (2), and 1 eye of group (3). In the cases where S. epidermidis was decreased by CMX topical use Propionibacterium acnes was increased. CONCLUSIONS: There is a possibility that preoperative topical use of CMX can reduce S. epidermidis. On the other hand, it might increase P. acnes. Considering these results and the fact that there was no difference in effectiveness in the aqueous humor cultures, preoperative CMX topical use may not prevent postoperative endophthalmitis except for endophthalmitis due to S. epidermidis.