Preoperative gentamicin eye drops and chlorhexidine solution in cataract surgery. Experimental and clinical results

PURPOSE. 1) To evaluate the effects on the conjunctival flora of gentamicin ophthalmic eye drops 0.3%, given four times in 45 minutes, and a conjuncti val rinse with 10 ml chlorhexidine 0.05% solution. 2) To investigate retros pectively the rate of endophthalmitis after cataract operations when these antimicrobials were applied preoperatively. METHODS. Seventy-six patients undergoing standard phacoemulsification opera tions were enrolled in the experimental part of the study. Cultures were ta ken preoperatively, 5 minutes after prophylaxis with either chlorhexidine o r gentamicin. To assess the combined effects of chlorhexidine and gentamici n, cultures were taken after the cataract operation. Hospital charts were r eviewed for cases of endophthalmitis in 1994 and 1995, when this prophylact ic protocol was used at the St Erik's cataract surgery department. RESULTS. The conjunctival microflora was significantly suppressed by chlorh exidine rinsing alone (p = 0.001), while no other significant anti-bacteria l effects were observed with the experimental prophylaxis. The endophthalmi tis rate was 32/12. 806 operations (0.25%). CONCLUSIONS. Topical rinsing with chlorhexidine solution suppresses conjunc tival flora in the short term. Combined topical chlorhexidine and gentamici n prophylaxis does not eliminate postoperative endophthalmitis caused by gr am-positive bacteria.