Eyeworld

20 July 2018 EW NEWS & OPINION Research highlight by Maxine Lipner EyeWorld Senior Contributing Writer the two to each other and found that the difference between the 2.64 and the 1.86 was not statistically significant," Dr. Mikelberg said. The fact that both of the drugs showed a relationship meant that investigators had to broaden their initial thinking. "If it was only the prostaglandins, we would hypoth- esize it's some mechanism that prostaglandins are known to have," Dr. Mikelberg said. "But it wasn't. It was both the prostaglandins and the beta blockers." There are several possibilities to explain what might be occurring, he continued. "One hypothesis is patients are put on these medica- tions because they have elevated IOP with or without glaucoma," he said. "Maybe it's the diagnosis of glaucoma that puts these patients at increased risk." Another hypothesis is that patients are put on this medication because of a complication in the surgery. "A patient may have ele- vated IOP in the context of cataract surgery if the cataract surgery was complicated." When there are com- plications with cataract surgery, one of the side effects could be elevat- ed IOP, which would then lead to using these eye drops, Dr. Mikelberg explained. So it may have nothing to do with the IOP or glaucoma but instead could indicate that these pa- tients had experienced complicated cataract surgery, Dr. Mikelberg said, "There were 508 patients who fit that criteria," Dr. Mikelberg said. They then selected 5,080 individuals from the database who had under- gone cataract surgery but not devel- oped postoperative CME to serve as controls. In addition to considering the prostaglandins, investigators designed the study to look at a couple of other medications that they thought would not interact to use on a control basis, Dr. Mikelberg explained. "For example, we always throw in a systemic medication that there's no way could have a rela- tionship to CME," he said. In this case, the oral medicine ranitidine was used, as well as beta blocker eye drops also not suspected of being related to CME occurrence. "We in- cluded that medication because we thought it would be a useful nega- tive control," Dr. Mikelberg said. Investigators were surprised to find that not only were the pros- taglandins significantly associated with an increased risk of developing postoperative CME, but also that the beta blockers were an equally power- ful risk factor here. Equivalent risk Investigators showed that the rela- tive risk ratio with the beta blocker was 2.64 and with the prostaglan- din analog was 1.86. "That might suggest that the beta blocker is even worse, however, we then compared cataract surgery increases the risk of developing CME," according to Frederick Mikelberg, MD, professor, Department of Ophthalmology and Visual Sciences, University of British Columbia. Investigators decided it might be interesting to take a closer look at this. "Ideally we would do a pro- spective randomized trial, but that's not going to happen because this is a relatively low incidence disease," Dr. Mikelberg said. They decided to work with a large administrative database and look for associations. Using a PharMetrics Plus database of 150 million patients, investigators looked for those who had developed postoperative CME. Considering possible connection to medications I s there an association between postoperative topical prosta- glandin analog (PGA) or topical beta blocker use and the inci- dence of pseudophakic cystoid macular edema (CME)? This is what a study 1 published in the Journal of Glaucoma examined. Initially investigators honed in on prostaglandin analog drops alone. "Ever since the prostaglandin analog drops came out in the late 1990s, there has been discussion on whether use of prostaglandin analogs in patients who have had Post-cataract CME under examination Both prostaglandins and beta blockers were found to be risk factors for developing postoperative CME. Source: Elizabeth Davis, MD " The take-home message is that the use of a beta blocker or prostaglandin analog in the context of a patient who has had cataract surgery somewhat increases the risk of developing CME. " —Frederick Mikelberg, MD

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