EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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I OCTOBER 2020 | EYEWORLD | 49 immediately stopped," Dr. Nijm said. "I also had been using additional viscoelastic to try and protect the corneal endothelium from the increased ultrasound power, but in doing so, I may have inadvertently reduced fluid movement as well." Dr. Nijm said there is a careful balance between creating a pocket under the viscoelastic when removing the nucleus and keeping the vis- coelastic up against the cornea for endothelial protection, while not restricting fluid movement in the eye. "As soon as I noticed whitening, I stopped, removed the phaco handpiece, and tested it for occlusion. At that point, I ensured an adequate pocket was present to allow fluid egress and carefully removed the remainder of the cata- ract with as little energy as possible," Dr. Nijm continued. She said the wound was leaky from the mi- nor burn and required three sutures at the end to close. The patient had 2 D of astigmatism postop, which was much less than expected. Dr. Nijm said there is usually more astigmatism to start, and over time (several months), it tends to dissipate. "It was a good lesson for me early on and is something to always be aware of," Dr. Nijm said. Dr. Nijm offered the following pearls to avoid instances of wound burn: • Understand the importance of fluid move- ment to allow the egress of fluid and the cornea to cool. There is heat generated at the ultrasound tip, and if there isn't enough fluid movement, it can cause a burn. • Pre-chop as much as possible when you have a dense nucleus. miLOOP (Carl Zeiss Meditec) can be helpful to accomplish that in cases of mature cataract. • Create a precise incision and look for signs early on (such as a white, smoky appearance in the anterior chamber as you phaco). • Once whitening at the wound occurs, a cor- neal burn has already taken place. Therefore, continued on page 50 Kevin Miller, MD, conducted an experiment to study the thermal effects of phaco. The silicone test chambers cap- ping each phaco probe simulate the cornea. The rubber bands simulate compression by the corneal incision. An infrared thermal camera (not shown) measures the heat produced at the "incisions" after ultrasound is activated. This image by an FLIR camera shows the heat generated by the three probes. The highest temperate in degrees Celsius within each of the three circles is displayed to the right. Any temperature above 50 degrees Celsius is capable of producing a corneal burn. Source (all): Kevin Miller, MD