How to reduce free radicals during phacoemulsification: electron paramagnetic resonance measurements comparing the production of free radicals in different use cases.

PURPOSE: To detect free radicals during phacoemulsification in different use cases and with emulsification of lens tissue.

SETTING

Institute for Interfacial Engineering and Biotechnology, Fraunhofer Institute, Stuttgart, Germany.

DESIGN

Experimental study.

METHODS

3 experimental setups were used: (1) setup without running fluidics to produce air bubbles inside the system, (2) circulation fluidic setup to compare measurements with and without cataractous lens material, and (3) a surgery-comparable system that closely mimics a realistic setup. Porcine lenses were incubated for 1.25 hours in formalin to simulate middle hard cataracts and emulsified in a test chamber. Free radicals were captured by the spin-trapping agent 5,5'-dimethyl-1-pyrroline N-oxide and measured using electron paramagnetic resonance spectroscopy.

RESULTS

Hydroxyl radicals were the predominant free radicals detected. The maximum amount of radicals was produced when air bubbles were allowed to build up inside the system. Less radicals were produced during lens emulsification compared with application without lens. This effect was enhanced when the phacotip was in close contact with the lens during the whole procedure. In the surgery-comparable setup, the least amount of free radicals was detected.

CONCLUSIONS

For the first time, we were able to analyze free radicals during phacoemulsification of lens tissue. We show that emulsification of lens tissue reduces the production of free radicals, an effect that is enhanced during close contact of the tissue with the phacotip. In addition, we show that air bubbles should be avoided during cataract surgery because they may enhance free radical production. Furthermore, running fluidics remove most of the radicals making oxidative stress less likely.