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60 | EYEWORLD | JUNE 2019 G UCOMA PRESENTATION SPOTLIGHT by Liz Hillman EyeWorld Senior Staff Writer Contact information Grover: dgrover@glaucomaassociates. com Radcliffe: drradcliffe@gmail.com 10 is average, above 10 is good, and below 10 is correlated with a greater risk for progression, Dr. Grover said. Until somewhat recently there were not well-designed prospective studies confirming the connection between corneal hysteresis and progression or glaucoma development. In 2013, Medeiros et al. published a prospective longitu- dinal study that evaluated corneal hysteresis as a risk factor for glaucoma progression. 1 Overall, corneal hysteresis measurements were found "significantly associated with glaucoma progres- sion," according to the investigators. "Eyes with lower CH had faster rates of visual field loss than those with higher CH," Medeiros et al. wrote. "The prospective longi- tudinal design of this study supports the role of CH as an important factor to be considered in the assessment of the risk of progression in patients with glaucoma." More specifically, corneal hysteresis was two times more predictive of visual field progres- sion, compared to Goldman applanation, and three times more predictive than central corneal thickness. Another study by Susanna et al. published in 2018 found that corneal hysteresis could be used as a risk factor for predicting even the development of glaucoma, with lower corneal hysteresis measurements significantly associated with increased risk. 2 "The evidence for corneal hysteresis as a risk factor is in some ways stronger than the evidence for corneal thickness, which we all use and is the standard of care," said Nathan Radcliffe, MD. Recognition of corneal hysteresis as a risk factor, however, is lagging. Some say it's just a research tool, Dr. Radcliffe said, but he coun- tered that there are ways it directly impacts clinical management. It can help identify pa- tients who are over or under treated; tells which eyes will have pressure reductions after cataract surgery; can help in MIGS decision making; and helps physicians understand how much pressure reduction they might get from starting a medication or from laser trabeculoplasty, Dr. Radcliffe said. T here's a test that can help assess a pa- tient's risk for glaucoma development and progression that Davinder Grover, MD, said many ophthalmologists are not using and may not even know about. It's called corneal hysteresis, which is a measure of how well the eye absorbs and dissipates energy. To Dr. Grover, corneal hyster- esis is a "glaucoma vital sign" that he finds "es- sential" as he makes decisions for his patients' glaucoma treatment plans. Corneal hysteresis, as a biomechanical property of visco-elasticity, is measured by a device similar to the tonometer "puff test." A bidirectional applanation system, the Ocular Response Analyzer (Reichert Technologies), calculates corneal hysteresis as the difference in pressure from when the cornea bends inward upon an air puff and the pressure when it bends outward again. A corneal hysteresis of A glaucoma risk factor that physicians might not be measuring for yet About the doctors Davinder Grover, MD Glaucoma Associates of Texas Dallas Nathan Radcliffe, MD Assistant professor of ophthalmology Icahn School of Medicine, Mount Sinai New York References 1. Medeiros FA, et al. Corneal hys- teresis as a risk factor for glau- coma progression: a prospective longitudinal study. Ophthalmology. 2013;120:1533–40. 2. Susanna CN, et al. A prospec- tive longitudinal study to investi- gate corneal hysteresis as a risk factor for predicting development of glaucoma. Am J Ophthalmol. 2018;187:148–152. Dr. Radcliffe measures his own corneal hysteresis. Source: Nathan Radcliffe, MD

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