Results favor microcoaxial incision technique for limiting bacterial ingress

April 30, 2007

Results of a study performed in an animal model demonstrate that bimanual phacoemulsification wounds allow significantly greater bacterial ingress from the ocular surface compared with a microcoaxial incision, said Vaishali A. Vasavada, MS.

Results of a study performed in an animal model demonstrate that bimanual phacoemulsification wounds allow significantly greater bacterial ingress from the ocular surface compared with a microcoaxial incision, said Vaishali A. Vasavada, MS.

The investigation was performed by Dr. Vasavada and colleagues at the Iladevi Cataract & IOL Research Centre, Ahmedabad, Gujarat, India. The study included 20 rabbits that had the first eye randomized to undergo phacoemulsification (phaco) with bimanual or microcoaxial phaco and then underwent the alternate procedure in the fellow eye. Bimanual phaco was performed with a clear corneal 1.2-mm incision for the phaco tip and a 1.4-mm incision for the irrigating chopper; the microcoaxial technique involved a 2.2-mm incision.

After irrigation/aspiration, stromal hydration was performed for all wounds, a control aqueous aspirate was obtained, then a 0.5 ml suspension containing Staphylococcus epidermidis was instilled on the ocular surface. After waiting 2 minutes, a 0.1 ml aspirate of aqueous humor was withdrawn and sent for 24-hour culture and microbiological analysis of colony forming units of Staphylococcus epidermidis per 0.1 ml.

The results showed significantly higher contamination in the bimanual phaco eyes compared with the microcoaxial eyes. The significant difference remained in subgroup analyses considering only eyes that had no clinical evidence of wound distortion and in those judged to have distorted wounds.

"Our results are supported by a recent study that reported microincision coaxial phaco induces less wound stress and alteration of wound morphology than bimanual incisions," Dr. Vasavada said. "Nevertheless, we still found bacterial ingress in both study groups."

"The take-home message is, even with the smallest of clear, corneal incisions, wound integrity is crucial," Dr. Vasavada concluded. "Surgeons should always look for incision distortion at the end of the case and should not hesitate to suture if necessary."