San Francisco-Cataract removal using 0.7-mm instruments represents the latest development in the evolution of the bimanual phacoemulsification technique, said Amar Agarwal, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.
"We first described bimanual phaco-emulsification through a 1-mm incision in 1998 and termed that procedure Phakonit," said Dr. Agarwal, of Dr. Agarwal's Eye Hospital and Eye Research Centre, Chennai, India. "With this new instrumentation, surgery through a sub-1-mm incision is now possible. This procedure, which we are calling Microphakonit, allows cataract removal through the smallest incision described to date.
The 0.7-mm irrigating chopper features a sharp cutting edge that allows it to chop cataracts of any density using a karate chopping or quick chopping technique. To maximize the amount of fluid coming out of the irrigating chopper and optimize fluidics, it is designed with a single end opening rather than dual side openings. However, due to its small gauge, use of gas-forced infusion is essential to increase fluid flow and maintain anterior chamber stability.
For that purpose, Dr. Agarwal uses the internal gas-forced infusion of the Accurus surgical system (Alcon Laboratories), although an external system using an air pump purchased at an aquarium shop offers another alternative.
"With an internal system, we can regulate the amount of air entering the infusion bottle and titrate the system to avoid surge and anterior chamber collapse," Dr. Agarwal explained.
The anterior vented gas-forced infusion system of the Accurus is composed of an air pump and regulator. The pump pushes air into the irrigating solution bottle so that the fluid is pushed into the eye without adjusting bottle height. When performing Microphakonit, Dr. Agarwal sets the infusion pump at 100 mm Hg. In a study measuring fluid flow from the 0.7-mm irrigating chopper using that setting, he found the exit rate was 65 ml/min.
"For surgeons who use an external pump, we have found that setting the pump's regulator switch for high pressure results in an irrigating chopper flow rate equivalent to that achieved when using the Accurus set at 100 mm Hg," Dr. Agarwal said.