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EW GLAUCOMA 72 October 2017 by Maxine Lipner EyeWorld Senior Contributing Writer of asking the patient to stay in a sleep lab for 24 hours, we get a lot of information," Dr. De Moraes said. What's more, it's simple and inexpensive. Clinically, this study confirmed what others had shown retrospec- tively, Dr. De Moraes noted, adding that this is also a way of answering why a patient is progressing despite controlled pressure. If an open angle patient has severe glaucoma and the practitioner is concerned about pro- gression, the water drinking test can be given, and if the peak is above 18, therapy could be escalated. There are contraindications, however. "For example, if the pa- tient has heart or kidney failure and cannot digest a lot of liquid, you're not going to do the test," Dr. De Moraes said. Dr. De Moraes hopes that practitioners come away from the study with the understanding that it's possible to better assess a pa- tient's pressure profile with this test because it can reveal information that's otherwise concealed, thereby helping you prevent the patient from losing vision in the future. EW Reference 1. De Moraes CG, et al. Predictive value of the water drinking test and the risk of glauco- matous visual field progression. J Glaucoma. 2017;26:767–773. Editors' note: Dr. De Moraes has no financial interests related to his comments. Contact information De Moraes: cvd2109@columbia.edu difference between this peak and the baseline. Patients were then exam- ined at regular 6-month intervals, plus or minus 2, until they either needed more therapy or they pro- gressed, based on their visual fields. "Our most important finding was that in a statistical model that looks at the risk of progression, the higher the peak pressure during the test, the greater the risk of progres- sion," Dr. De Moraes said. "For each millimeter higher, the risk increased by approximately 11%." When investigators compared outcomes for those who had a peak of less than 18 to those who had a peak greater than this, they found that those over the 18 mm Hg mark had a two- fold increased risk of progression. For many, this would have signifi- cant clinical implications. "Had we followed these patients with regular snapshot measurements during of- fice visits, we would think that they were well controlled with pressures lower than 18," Dr. De Moraes said, adding that with this test, they were able to sort out some patients who might not be well controlled. Clinical role This has implications for the com- mon scenario in which patients keep progressing even though their pressures are seemingly well con- trolled. "What we showed in this study is that when you measure it low, it may not actually be low," Dr. De Moraes said. If you could mea- sure patients around the clock, that would likely also show this. One of the key points is that it's able to ascertain the circadian rhythm. "In 45 minutes, instead risk of progression, they said there isn't strong evidence yet." Launching the prospective study Investigators decided to launch a prospective, longitudinal study to assess the predictive value of the water drinking stress test for estimat- ing the risk for progression of visual field loss. Included were 144 eyes with primary open angle glaucoma. Patients were either being treated with drops or had undergone laser surgery and had pressures equal to or lower than 18 mm Hg. This mark was used because some studies, especially one randomized clinical trial—the Advanced Glaucoma In- tervention Study—reported a cutoff value of 18 that was associated with a lower risk of progression. "We didn't want to enroll patients in the study and have them immediately undergo escalated treatment because it would affect our results," Dr. De Moraes said. All of the screened patients underwent the water drinking test at a baseline visit. Prior to the test, patients were asked not to drink liquids for 2 hours to avoid a confounding effect. Then they were asked to drink 27 ounces in a 5-minute period. "Just before they drank the water, we checked the pressure, which was their base- line," Dr. De Moraes said. "Then we measured every 15 minutes, three times." Patients were tested 15, 30, and 45 minutes after baseline. The highest measurement was termed the peak, and the variability was the Studying test to help predict field progression I t's the classic glaucoma quan- dary: During office hours, a patient seems well controlled, yet he or she continues to lose vision. In a recent study published in the Journal of Glaucoma, practitioners considered the value of using a water drinking stress test to determine likely glaucoma field progression, according to Carlos Gustavo De Moraes, MD, associate professor, Columbia University, New York. 1 The study was an outgrowth of earlier work. "Our group and many others in the world have previously published on the role of these tests to assess peak IOP that occurs outside of office visits," Dr. De Moraes said, adding that during office hours, physicians only get a snapshot of patients' pressure and often do not capture it at its peak. "The water drinking test has been used to estimate this peak," he said. There's also research suggesting that such peaks are associated with not only the severity of glaucoma but also the speed that patients' field loss is progressing. However, prior studies of the water drinking stress test have been either cross-sectional or retrospective. "This is an import- ant limitation that limited a con- sensus determination by the World Glaucoma Association," Dr. De Moraes said. "When they were asked if this test could be used to predict Water drinking test for glaucoma Research highlight OCT to determine anatomic shape in myopic eyes Anthony Kuo, MD, discusses OCT imaging for pathologic myopia.

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