Comparison of 2 moxifloxacin regimens for preoperative prophylaxis: prospective randomized triple-masked trial. Part 2: residual conjunctival flora

To determine whether a regimen of topical moxifloxacin hydrochloride ophthalmic solution 0.5% (Vigamox) administered on the day of cataract surgery reduces conjunctival bacterial flora.

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

Seventy-four patients were prospectively randomized to receive Vigamox 4 times 1 day before surgery plus 1 drop 2 hours preoperatively (Group 1) and 74 patients, to receive Vigamox 2 hours before surgery and every 15 minutes in the first hour only (Group 2). Conjunctival swabs from the upper and lower lid margins and lower fornix were taken before and after Vigamox instillation. Aliquots were spread on chocolate blood, anaerobic basal, and nutrient agars. The number of bacterial colony-forming units (CFU) on the plates was counted with a grid technique and expressed as log values. The total number of CFU per eye and mean percentage reduction in CFU after instillation were calculated. Bacterial species were identified using biochemical and biophysical reactions. Wilcoxon signed ranked and Mann-Whitney tests and multiple linear regression were applied.

In Group 1, the median colony count decreased from 1284.00 CFU +/- 643.18 (SD) before Vigamox instillation to 65.00 +/- 72.61 CFU after instillation (93.12% reduction) (P<.001) and in Group 2, from 1634.00 +/- 769.27 CFU to 75.00 +/- 81.23 CFU (93.28% reduction) (P<.001). The percentage reduction after instillation was similar between the 2 groups (P = .09).

Both Vigamox regimens reduced the number of CFU of conjunctival flora, indicating that instillation beginning on the day of surgery is effective.