The role of intraocular lenses in anterior chamber contamination during cataract surgery

Background: Bacterial endophthalmitis is a rare vision-threatening disease, usually caused by microorganisms that are natural inhabitants of the eye lids and conjunctiva. This study was conducted to investigate the role of intraocular lenses (IOLs) in introducing bacterial contamination into the eye during cataract surgery and the efficacy of povidone-iodine solution in prevention this ocular inoculum. Methods: Fifty patients underwent routine cataract surgery and intraocular lens implantation. One group of the patients was pretreated with external disinfection using povidone-iodine 4% before surgery, while the other group was only pretreated with saline irrigation. Before IOL implantation, a test IOL was placed on the conjunctiva and taken for microbiological studies. Anterior chamber tap was done at the beginning and at the end of each operation. Positive bacterial growth was followed by bacterial identification and sensitivity tests to various antibiotics. Results: Bacterial growth was obtained in 14 of the 50 eyes (28%); in 5 eyes the organism was cultured from tapped aqueous and in 9 eyes from the test IOLs. Prophylactic use of povidone-iodine 4% solution effectively reduced the contamination rate from 34.7% to 16.7%. Coagulase-negative staphylococci were the most common organisms isolated (72%). Most organisms were sensitive to vancomycin (86%) and to fucidic acid (71%). There were no cases of clinical endophthalmitis. Conclusions: IOLs are apparently potential vehicles for introduction of intraocular bacterial contamination. Instillation of povidone-iodine 4% into the cul-de-sac reduces the risk of bacterial inoculum. Vancomycin is the most effective single agent against intraocular contamination. In order to reduce potential intraocular contamination it is advisable to avoid contact between the IOL and ocular tissues.