Eyeworld

20 | EYEWORLD | DECEMBER 2019 ASCRS NEWS EYEWORLD JOURNAL CLUB by Cassandra C. Brooks, MD, Kevin Jackson, MD, Mark F. Goerlitz-Jessen, MD, Pratap Challa, MD the potential for these adverse effects, surgeons continuously seek ways to minimize damage caused by ultrasound energy from phacoemulsi- fication while preserving its efficiency. 6 Overview of study In this study, Wan et al. hypothesized that intra- ocular hypothermia during phacoemulsification may reduce postoperative inflammation and en- dothelial cell damage. The study was composed of an animal trial with 40 rabbits (40 eyes) and a randomized clinical trial with 80 patients (80 eyes) with a hard nuclear cataract (grade III–V, Lens Opacities Classification System III) that underwent phacoemulsification by one surgeon at a single institution. The preoperative visual and corneal char- acteristics for the clinical trial were obtained, though not provided. Phacoemulsification for the animal study was performed with an energy of 50% and a phacoemulsification time of 20 seconds in total (phacoemulsification for 5 sec- onds, pause for 5 seconds, repeated four times) while phacoemulsification energy and time were recorded at the conclusion of each operation in the randomized clinical trial. Real-time intraocu- lar temperature was obtained using a thermom- eter with thermocouple probes inserted into the anterior chamber (AC) as well as the corneal Introduction Cataracts affect approximately 24.4 million people in the United States and are expected to be responsible for vision loss in almost 40 million people by 2030. Cataract surgery is one of the most common procedures performed today with 3.6 million surgeries performed in the United States in 2015. 1,2 Phacoemulsifica- tion has become the most common method of cataract extraction due to its efficiency, safety profile, and use of a small incision. However, phacoemulsification can have undesired ef- fects when excessive ultrasound energy is used, which is more likely as a cataract becomes more mature. 3 Unfortunately, excess ultrasound energy can affect nearby ocular structures via dissi- pated vibrational energy and thermal damage. The undesired effects attributed to excess ultrasound energy include thermal injuries to the incision and damage to the corneal endo- thelium. Thermal injuries to the incision lead to difficult wound closure, wound leakage, damage to corneal stroma, fistula formation, and high postoperative astigmatism. 4 Damage to the corneal endothelium during surgery can acutely and chronically impair endothelial cell function in corneal transparency given the limited re- generative capacity of endothelial cells. 5 Due to Review of "Effect of Hypothermic in Eyes with Hard Nuclear Cataract: Pratap Challa, MD Residency Program Director Duke University Durham, North Carolina Kevin Jackson, MD, Mark F. Goerlitz-Jessen, MD, Cassandra C. Brooks, MD, and Pratap Challa, MD. Source: Pratap Challa, MD Although it has been debated in the past, the concept of cooling irrigation fluid for phaco has garnered little attention in the past decade. I asked the Duke residents to review this December JCRS study, which analyzes the potential benefits of colder infusion for hard cataracts. —David F. Chang, MD EyeWorld Journal Club Editor

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