Seven different prophylactic regimens were evaluated for their effectiveness in decreasing or eradicating bacteria on the eyelids before surgery. The antibiotics used were a solution of polymyxin, neomycin, and gramicidin (in three schedules); an ointment of polymyxin, neomycin, and bacitracin (one schedule); chloramphenicol, 0.5% solution (one schedule); and gentamycin, 1.0% solution (two schedules). Six of the seven schedules (all but chloramphenicol in its single schedule) reduced bacterial counts on the lids when compared with control eyes receiving no antibiotics. None of the schedules was very effective, however. The most effective (gentamycin drops given every ten minutes for two hours) only eradicated bacteria in 44% of the eyes treated. We concluded that an effective antibiotic by a practical schedule would reduce the lid bacterial count but could not be relied on to sterilize the lids routinely.
Whitney CR, Anderson RP, Allansmith MR. Preoperatively Administered AntibioticsTheir Effect on Bacterial Counts of the Eyelids. Arch Ophthalmol. 1972;87(2):155-160. doi:10.1001/archopht.1972.01000020157007