Eyeworld

101 EW GLAUCOMA March 2016 Based on a handful of small studies, estimates for the prevalence of sleep apnea among patients with NTG range from 6–50%, with obstructive sleep apnea increasing with age in cohorts of NTG patients. Sleep apnea may directly contribute to the pathophysiology of NTG by inducing ischemia by reducing ocular perfusion pressure. "Sleep apnea occurs at night," Dr. Ritch explained, "when IOP is typ- ically at its highest and blood pres- sure at its lowest. These 3 separate risk factors for glaucoma are present simultaneously and are additive. I think NTG is primarily a nocturnal disorder." We may not be very good at identifying which of our patients have sleep apnea. "The typical pa- tient with sleep apnea is an over- weight male with a thick neck who consumes alcohol, particularly just before bedtime, and who snores," Dr. Ritch said. "But many patients do not fit this risk pattern. Anyone can have sleep apnea." "It is important to know that at present, it is estimated that about 80% of obstructive sleep apnea pa- tients remain undiagnosed as such," Dr. Ritch said. "I order polysomnog- raphy on many of my NTG patients who are progressing despite what appears to be adequate IOP con- trol and in whom nocturnal blood pressure overdipping has been ruled out." He pointed out that treatments such as continuous positive airway pressure (CPAP) can reduce ischemia and may reduce glaucoma risk in patients with sleep apnea. He also advised that patients with sleep apnea be screened for glaucoma. NTG and the risk of blindness Tetsuya Yamamoto, MD, Gifu, Japan, has conducted long-term analysis of patients with NTG. "The 20-year incidence of blindness in normal tension glaucoma is 9.9% in 1 eye and 1.5% in both eyes," he said. How can blindness be avoided? "Achieving a consistent IOP reduc- tion of 20–30% is associated with a 93–96% probability of stable NTG without visual field progression over 15 years of treatment," he explained. "Likewise, achieving target IOP of 10–11 mm Hg confers a 90% or greater probability of NTG stability over 15 years." Is there an optimal modality for IOP reduction in NTG? Dr. Yamamoto thinks so. "Trabeculec- tomy is effective in achieving target IOP and stabilizing the visual field." He added, "Patients treated with medications achieved a mean IOP reduction of approximately 20%, which was associated with a 1.4-fold reduction in visual field progression. In contrast, patients treated with surgery achieved a mean 40% IOP reduction and a 5.7-fold slower rate of visual field progression. If medica- tions alone fail to achieve target IOP reduction of at least 20–30%, surgery should be considered." EW Editors' note: The physicians have no financial interests related to their comments. Contact information Araie: araie-tky@umin.net Park: kihopark@snu.ac.kr Ritch: ritchmd@earthlink.net Yamamoto: mmc-gif@umin.net " Based on a study conducted in the United States, risk factors for progression of NTG include disc hemorrhage, female gender, and a history of migraine headaches. " –Ki Ho Park, MD Premier Edge ® Safety Knives X Patented and ergonomically designed safety shield with ribbed thumb- grip supports one-handed operation and ambidextrous usability © 2015 OASIS Medical, Inc. OASIS name and logo are registered trademarks of OASIS Medical, Inc. 514 S. Vermont Ave, Glendora, CA 91741 LIT-SURG-AD 4.2015 GENTLE & EFFECTIVE EXPANSION. X Available in 7.0mm and 6.25mm for an unimpeded view during complicated small pupil surgeries SAFETY & EFFICIENCY DIAMOND-LIKE PERFORMANCE. X Proprietary technology with the latest specialty blade edge processing Find out more about how we can help your practice. (800) 528-9786 (USA Toll Free) 909-305-5400 customerservice@oasismedical.com www.oasismedical.com OASIS ® Iris Expander Feather ® Scalpels NEW DESIGN

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