APR 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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April 2013 EW CATARACT 31 Sound advice for soothing patients during cataract surgery by Maxine Lipner EyeWorld Senior Contributing Writer Binaural beats provide relaxation response C ataract surgery is routine for practitioners, but for patients it can be fraught with worry. "Anxiety is the most common psychological problem that occurs in patients undergoing anesthesia, especially in the field of ophthalmology where most of the patients are operated on while awake under local anesthesia," said Pornpattana Vichitvejpaisal, MD, Chiang Mai University, Chiang Mai, Thailand. "Worries about loss of control, being in an unfamiliar environment, and expectations for the good result of surgery can produce a high level of pre- and operative anxiety for the patients." Dr. Vichitvejpaisal has experience to show that an unusual approach to reducing anxiety may help to change all of that. Known as binaural beats, two different tones are paired to produce a relaxing effect. Together with other researchers at Chiang Mai University, Dr. Vichitvejpaisal found that use of binaural beats during cataract surgery can soothe patients, reducing systolic blood pressure as well as anxiety. Anxiety reducing strategies He pointed out that the use of adjunctive therapy during surgery has proven successful before. "Recent studies of various interventions on anxiolytic effects during operations have revealed good results," Dr. Vichitvejpaisal said. "Among these, musical interventions during surgery have been reported to be a noninvasive, inexpensive, and effective means of controlling perioperative anxiety levels in patients." Indeed, he noted, the use of prerecorded music has been found to relieve anxiety in patients undergoing various surgical procedures. For those undergoing cataract surgery, for which they are generally awake while it is going on, anxiety can be a particular concern. Dr. Vichitvejpaisal observed that during cataract surgery under local anesthesia patients are continuously exposed to a cacophony of potentially anxiety-provoking sounds, including the noise of the phaco machine, not With binaural beats, brain waves go into the alpha range, evoking relaxation. When two auditory stimuli of slightly different frequencies are presented to each ear, binaural beats are perceived by the listener, with the beat heard equal to the difference in frequency between each ear. to mention any discussions taking place among the surgical team. Binaural beats benefits Using traditional music to soothe patients during surgery has been investigated by others , but binaural beats are far from ordinary. "Binaural beats reportedly influence the brain in more subtle ways through the entrainment of brain waves and can be used to reduce anxiety and provide other health benefits such as control over pain," Dr. Vichitvejpaisal said. "Binaural beats are auditory processing artifacts, the perception of which arises in the brain for specific physical stimuli." The effect itself is far from new. Dr. Vichitvejpaisal said that this was discovered in 1839 by Heinrich Wilhelm Dove. "When two auditory stimuli of different frequency are presented to each ear, binaural beats are perceived by the listener," Dr. Vichitvejpaisal said. "The frequency of the tones must be about 1,000 to 1,500 hertz for the beating to be heard." The binaural beat frequency, in which a single tone is perceived, is equal to the difference between the frequencies applied to each ear, he explained. This difference between the two disparate frequencies must be small for the effect to occur—no more than about 30 hertz, Dr. Vichitvejpaisal stressed. "For example, if a 400 hertz sine wave is played into the right ear and a 410 hertz one into the left ear, the brain is entrained toward the beat frequency of 10 hertz," Dr. Vichitvejpaisal said. This frequency is in the alpha range in which relaxation is evoked, he explained. Could such an effect help to calm patients undergoing cataract surgery? Dr. Vichitvejpaisal set out During cataract surgery patients can be lulled into a sense of calm by binaural beats. Source (all): Pornpattana Vichitvejpaisal, MD to determine just that. "The aim of our study was to investigate the anxiolytic effect of binaural beat audio and musical interventions during cataract surgery," he said. In the study, 141 patients undergoing routine cataract removal under local retrobulbar block were randomly assigned to one of three groups. The first group listened to binaural beats during the procedure, the second to music, and the third underwent traditional surgery and served as controls. For those in the binaural beat group, within the first five minutes the frequency was set to slow into the 10 hertz alpha-inducing range. On the 60-minute soundtrack, relaxing musical arrangements were paired with harmonic sounds from nature such as the rush of a waterfall, the beat of the ocean on the shore, or the call of birds in the forest. When investigators reviewed patients' vital signs they determined that those in the binaural beats group showed the greatest reduction in heart rate during the procedure. Blood pressure was found to decrease in both the binaural beats and the music intervention groups. Meanwhile for the controls both systolic blood pressure and heart rate increased during that time. "Our study results supported the hypothesis that binaural beat audio and musical interventions during cataract surgery could significantly reduce patient anxiety levels and lower systolic blood pressure," Dr. Vichitvejpaisal said. Overall, he urges practitioners to consider incorporating binaural beats into their cataract surgical routines. He said that the cost is minimal and the method is noninvasive. "This should be taken into consideration as an alternative or adjuvant intervention in anesthesia for patients' great experience in surgery," he concluded. EW Editors' note: Dr. Vichitvejpaisal has no financial interests related to this article. Contact information Vichitvejpaisal: g_zard113@hotmail.com

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