THE ROLE OF INTRAOCULAR LENSES IN ANTERIOR-CHAMBER CONTAMINATION DURING CATARACT-SURGERY

Background: Bacterial endophthalmitis is a rare vision-threatening dis ease, 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 contam ination into the eye during cataract surgery and the efficacy of povid one-iodine solution in prevention this ocular inoculum. Methods: Fifty patients underwent routine cataract surgery and intraocular lens impl antation. One group of the patients was pretreated with external disin fection 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 en d of each operation. Positive bacterial growth was followed by bacteri al identification and sensitivity tests to various antibiotics. Result s: 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-negativ e staphylococci were the most common organisms isolated (72%). Most or ganisms 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 bacteri al contamination. Instillation of povidone-iodine 4% into the cul-de-s ac reduces the risk of bacterial inoculum. Vancomycin is the most effe ctive single agent against intraocular contamination. In order to redu ce potential intraocular contamination it is advisable to avoid contac t between the IOL and ocular tissues.