EyeWorld Asia-Pacific March 2017 Issue

43 EWAP CATARACT/IOL March 2017 Jersey), and ProVisc (Alcon). “Those are all very similar in their index of refraction and molecular weight,” Dr. Masket said, adding that with those there were no significant differences compared to results seen with balanced salt solution. Three other agents that had a higher index of refraction were also investigated, with a different outcome. “The index of refraction for the three prior agents was quite similar to balanced salt solution and therefore the results were similar,” Dr. Masket said. When investigators looked at Healon GV (Abbott Medical Optics), Amvisc Plus (Bausch + Lomb), and DisCoVisc (Alcon), which have a higher index of refraction, it was a different story. The DisCoVisc and Amvisc Plus, which have a similar index of refraction, both turned out to have a statistically significant difference in optical outcomes from balanced salt solution, Dr. Masket reported. With the Healon GV, there was a trend toward a difference noted, but this was not statistically significant. The differences are a result of the index of refraction. “The higher index of refraction agents do two things. They cause light to slow down going through the aberrometer and change the interface difference between index of refraction when going from air to the cornea,” Dr. Masket explained. “For those reasons, we tend to get a higher axial length as the device would read it, and it suggests a lower IOL power by about 0.5 D.” Practical applications Clinically, this can make a difference. For those who prefer to use OVDs during aberrometry due to concerns about wound leakage with balanced salt solution, Dr. Masket recommends keeping this in mind. “If the surgeon is not consistent with his or her wound construction and is concerned there will be fluid leakage from the incision and therefore cannot establish proper IOP to do aberrometry, he or she can use one of the low molecular weight agents such as Amvisc, Healon, or ProVisc,” Dr. Masket said. “On the other hand, if a surgeon is comfortable with incision construction and knows how to carefully hydrate without distorting the cornea, it’s fine to just work under balanced salt solution.” Dr. Masket hopes that practitioners come away from the study with an understanding of the importance of accurate aberrometry. “I see aberrometry as a valuable adjunct in trying to reach higher accuracy for IOL powers, given the need to match patient expectations with what we can deliver,” he said. “I believe in the benefit of aberrometry. But I think, like everything else, it depends on how you use it, and one needs to develop a facility for using it, for establishing physiologic IOP, with proper wound construction.” Going forward, investigators hope to tackle the idea of adjusting for OVD differences in index of refraction. “We’re in the process of restudying DisCoVisc,” Dr. Masket said. “[We’re trying] to establish appropriate nomograms for each of the agents that surgeons may choose to use.” EWAP Reference 1. Masket S, et al. Influence of ophthalmic viscosurgical devices on intraoperative aberrometry. J Cataract Refract Surg . 2016;42:990–4. Editors’ note: Dr. Masket has financial interests with Alcon. Contact information Masket : sammasket@aol.com Join the largest subspecialty society representing the fields of cornea and external disease. Member Benefits • Cornea: The Journal of Cornea and External Disease • Annual Meetings: Select discounted registration at membership events and educational programs • Video Ed: A weekly broadcast of clinical videos recorded live at national and international meetings • K era -net: The online forum for the exchange of clinical and scientific information www. Cornea Society .org