검안및콘택트렌즈학회지 2019 년제 18 권제 2 호 Ann Optom Contact Lens 2019;18(2):51-56 ISSN 2384-0919 (Print) ISSN 2384-0927 (Online) Original Article 사시수술중발생하는안구심반사빈도및연관인자에대한분석 Incidence and Factors that Affect the Oculocardiac Reflex during Strabismus Surgery 박형준 백혜정 Hyung Jun Park, MD, Hae Jung Paik, MD, PhD 가천대학교길병원안과학교실 Department of Ophthalmology, Gachon University Gil Medical Center, Incheon, Korea Purpose: To investigate incidence and factors associated with the occurrence of oculocardiac reflex (OCR) during strabismus surgery. Methods: Three hundred eighty-seven patients who underwent strabismus operation under general anesthesia participated in this retrospective study. OCR was defined as a heart rate (HR) reduction of more than 15%, when compared to baseline HR. When OCR occurred patient were treated with intravenous atropine (15 μg/kg) or release the tension on the muscle. The incidence and preoperative and intraoperative variable factors of the OCR were investigated. Results: An overall rate of 30.2% of the patients showed a positive OCR. There were significantly more OCR in the inferior oblique and rectus combine surgery than rectus surgery (p = 0.001), The occurrence rate of OCR within 5 minutes after operation was 88.8% in inferior oblique and rectus combine surgery and 80.0% in rectus surgery. Conclusions: Manipulation of inferior oblique muscle in patients with two muscle surgeries in each eye was a significant risk factor for OCR occurrence. Gentle manipulation of the extraocular muscles especially the oblique muscle is important in two muscle surgeries. Surgeon and Anesthesiologist needs to be more careful within 5 minutes after surgery in strabismus surgery. Ann Optom Contact Lens 2019;18(2):51-56 Key Words: Oculocardiac reflex; Oculomotor muscles; Risk factor; Sinus bradycardia; Strabismus surgery 서 론 안구심반사 (oculocardiac reflex) 는외안근의견인, 안구및안검에압박을가한후서맥등의부정맥이유발되는현상으로발생빈도는연구에따라 16-95% 로다양하며소아사시교정술의주요합병증중하나로알려져있다. 1-3 주로 Received: 2019. 5. 9. Revised: 2019. 6. 15. Accepted: 2019. 6. 17. Address reprint requests to Hae Jung Paik, MD, PhD Department of Ophthalmology, Gachon University Gil Medical Center, #21 Namdong-daero 774beon-gil, Namdong-gu, Incheon 21565, Korea Tel: 82-32-460-3364, Fax: 82-32-460-3358 E-mail: hjpaik@gilhospital.com 수술중서맥이나부정맥으로나타나지만, 심실세동및심정지의위험또한보고된바있으며, Sorenson and Gilmore 4 는안구심반사의결과로심정지가발생하여사망에이를수도있다고보고하였다. 5 사시수술중발생할수있는안구심반사의위험인자로는수술전기본심박동수가빠른환자, 9세이하의소아, 수술시조작하는근육의개수나종류, 근육당김의세기등이보고되었으며, 수술중발생할수있는서맥을예방하기위해, 수술전정맥또는피하로부교감신경차단제인 Atropine이나 Glycopyrrolate을사용하거나, 신경차단을시행하여안구심반사를줄일수있다는보고가있었다. 6-12 현재까지근육당김이사시수술중안구심반사의가장큰위험인자로알려져있으며, 이를예방하기위해수술중근 Copyright 2019, The Korean Optometry Society The Korean Contact Lens Study Society Annals of Optometry and Contact Lens is an Open Access Journal. All articles are distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 51
- 검안및콘택트렌즈학회지 2019 년제 18 권제 2 호 - 육조작을최소화하는것이안구심반사를줄일수있다는보고가있었으며, 성별, 수술시조작하는근육개수, 근육종류에따라안구심반사발생률이다르다는보고가있지만이에대해서는이견이있다. 6,7,12-14 이에본연구는사시수술중발생하는안구심반사의빈도및연관인자에대해알아보고자하였다. 대상과방법 2014년 7월부터 2018년 7월까지본원안과에서전신마취하에단일술자에의해수술을받은사시환자중수술후한달까지추적관찰이가능하였던직근과하사근수술환자를대상으로후향적으로조사및분석하였다. 대상환자에서심장수술과거력이있는환자, 선천성심질환으로수술을받은과거력이있는환자, 감염성심내막염을앓은과거력이있는환자, 기타심장질환및고혈압으로수술전후투약중인환자, 기관지천식을진단받은환자, 신경계질환이있거나사시수술을제외한선천백내장및녹내장등을진단받고안과수술을받은과거력이있는환자는제외하였다. 모든환자에서수술전신체상태를평가하기위해일반혈액검사, 생화학검사, 혈액응고검사, 일반요화학검사, 심전도검사, 단순흉부엑스선촬영검사를시행하였으며, 1% cyclopentolate hydrochloride와 1% tropicamide를 5분간격으로 3회점안후 30분후에조절마비굴절검사를시행하였다. 사시각은굴절이상을교정한뒤협조가가능한경우조절시표를이용하여 6 m 원거리와 33 cm 근거리에서교대가림검사로측정하였고, 협조가불가능한경우에만허쉬버그검사나크림스키검사로측정하였다. 양안운동검사를시행하여외안근기능항진및저하를확인하였다. 입체시는티트무스입체시검사 (Titmus Optical Inc., Chester, VA, USA) 를통해측정하였다. 전신마취시전처치로 Diazepam이나 Atropine 등의심박동수에영향을줄수있는약물은사용하지않았으며, 마취유도를위해 propofol 2 mg/kg을정맥주입한후 1.5-2.5 vol% 의 sevoflurane과 O 2 와 N 2O를각각 2 L/min를흡입하여마취를유지하였다. 수술중 5초마다심박동수를확인하였고, 수술중심전도모니터링은마취의료인에의하여이루어졌다. 안구심반사의정의는연구에따라약간차이가있으며, 본연구에서는수술시심박동수가기본값에서 15% 이상감소하거나부정맥이나타난경우로정의하였다. 4,15,16 심박동수의기본값은연구자에따라차이가있으며, 본연구에서는마취유도직전 15분동안관찰한평균심박동수를기 본값으로하였으며기본값의 15% 이상심박동수감소시정맥내 Atropine (15 μg/kg) 을주사하거나수술적조작을중단하였다. 17,18 안구심반사발생군과비발생군간의나이, 성별, 마취시간, 수술시간을비교하였으며, 사시종류에따라내직근, 외직근, 상직근, 하직근, 하사근에대하여수술을시행하였고, 직근은후전술과절제술로시행하였고, 하사근은근절제술, 후전술, 전치술을시행하였다. 직근에서후전술과절제술을각각시행한군간의안구심반사발생률을비교하였으며, 간헐성외사시진단하에양안외직근후전술시행한군과내사시진단하, 양안또는단안내직근후전술시행한군간의안구심반사발생률을비교하였으며, 직근만을단독으로시행한군과직근과사근을동시에시행한군간의안구심반사발생률을비교하였다. 직근과사근을동시에시행한경우모든환자에서사근을먼저수술하고직근을수술하였다. 통계분석은 SPSS 프로그램 Version 22.0 (IBM Corp., Armonk, NY, USA) 에서 chi-square test, Mann-Whitney U test을이용하여안구심반사발생군과비발생군의차이에대해비교하였다. p값이 0.05 미만인경우를통계적으로유의한것으로정의하였다. 본연구는임상연구심사위원회 (Institutional Review Board, IRB) 의승인하에진행되었으며, 헬싱키선언 (Declaration of Helsinki) 을준수하였다. 또한본논문에제시되어있는모든제품, 제조사와금전적인이해상충관계가없음을밝히는바이다. 결과 대상환자는총 387명으로 117명 (30.2%) 에서안구심반사가발생하였다. 이들의평균연령은 9.4 ± 7.4세, 남자 192명 (49.7%), 여성 195명 (50.3%) 이었다. 평균마취시간은 47.8 ± 22.4분, 평균수술시간은 43.9 ± 27.7분이었으며안구심반사발생군과비발생군간의연령, 성별, 마취시간, 수술시간은통계학적으로유의한차이가없었다 (p=0.119, p=0.734, p=0.357, p=0.899) (Table 1). 총 387명중간헐외사시로진단받은환자들 207명에대해양안외직근후전술을시행하였고, 내사시로진단받은환자들 33명에대해양안또는단안내직근후전술을시행하였다. 해리수직편위로진단받은환자들 13명에대해단안또는양안상직근후전술을시행하였으며, 간헐외사시와하사근기능항진증을동시에진단받은환자들 51명에대해양안외직근후전술과양안하사근후전술또는하사근절제술을시행하였다. 재발외사시로진단받은환자들은총 36명으로 16명에서양안내직근절제 52
- 박형준 백혜정 : 사시수술중발생하는안구심반사 - 술을시행하였으며, 20명에서단안외직근후전술과내직근절제술을시행하였다. 재발내사시로진단받은환자들은총 27명으로 14명에서양안외직근절제술을시행하였으며, 13명에서단안내직근후전술과외직근절제술을시행하였다. 상사근마비로진단된 12명의환자중 5명은선천성상사근마비로진단되었고단안하사근후전술을시행하였으며, 7명은단안하사근후전술, 반대안하직근후전술시행하였다. 해리수직편위와내사시가동시에진단된 3명의환자는단안하사근후전술과반대안하사근전치술을시행하였으며, 좌안하사시로진단된 5명의환자에서는단안상직근후전술과하직근절제술을시행하였다 (Table 2). 간헐외사시로진단받고양안외직근후전술을시행한 207명과내사시로진단받고양안또는단안내직근후전술을시행한 33명, 총 240명과양안재발외사시로진단받고양안내직근절제술을시행한 16명과양안재발내사시로진단받고양안외직근절제술시행한 14명, 총 30명에대해후전술과절제술에대해안구심반사발생빈도에대해비교하였고통계학 적으로유의한차이가없었다 (p=0.297) (Table 3). 간헐외사시로진단받은 207명의환자들에게양안외직근후전술을시행하였으며, 그중 60명 (28.9%) 에서안구심반사가발생하였으며, 내사시로진단받은 33명환자들에게양안또는단안내직근후전술을시행하였으며그중 6명 (18.1%) 에서안구심반사가발생하였다. 두군에서근육종류에따른안구심반사발생율은통계학적으로유의한차이가없었다 (p=0.910) (Table 3). 간헐외사시와하사근기능항진증을동시에진단받은환자총 51명에서양안외직근후전술과양안하사근후전술또는하사근절제술을시행하였으며, 그중 27명 (52.9%) 에서안구심반사가발생하였다. 간헐외사시로진단받은 207명, 내사시로진단받은 33명, 해리수직편위로진단받은 13명, 하사시로진단받은 5명, 총 288명에서직근에대해서만수술을시행하였으며그중 80명 (27.7%) 에서안구심반사가발생하였다. 하사근과직근을동시에수술한군에서직근에대해서만수술을시행한군에비해통계학적으로안구심반 Table 1. Comparison of the occurrence of the oculocardiac reflex according to the preoperative and intraoperative variables OCR (+) (n = 117) OCR (-) (n = 270) p-value * Age (years) 9.74 ± 5.01 9.25 ± 8.29 0.119 Male 51 (43.6) 141 (52.2) 0.734 Anesthesia time (minutes) 50.64 ± 36.40 46.66 ± 12.33 0.357 Operation time (minutes) 43.48 ± 65.63 44.16 ± 23.81 0.889 Values are presented as mean ± standard deviation or number (%) unless otherwise indicated. OCR = oculocardiac reflex. * Mann-Whitney U test; chi-square test. Table 2. Surgical name and number of patients according to diagnosis Diagnosis Operation name Number of patients Intermittent exotropia Bilateral LR recession 207 Esotropia Bilateral or unilateral MR recession 33 DVD Bilateral or unilateral SR recession 13 Intermittent exotropia with Bilateral LR recession, Bilateral IO recession or resection 51 inferior oblique overaction Recurrent exotropia Bilateral MR resection 16 Unilateral MR resection & LR recession 20 Recurrent esotropia Bilateral LR resection 14 Unilateral LR resection & MR recession 13 Congenital superior oblique palsy Unilateral IO recession 5 Superior oblique palsy Unilateral IO recession & fellow eye IR recession 7 DVD with esotropia Unilateral IO recession & fellow eye IO anterization 3 Hypotropia Unilateral SR recession & IR resection 5 Total 387 LR = lateral rectus muscle; MR = medial rectus muscle; DVD = dissociated vertical deviation; SR = superior rectus; IO = inferior oblique muscle; IR = inferior rectus. 53
- 검안및콘택트렌즈학회지 2019 년제 18 권제 2 호 - 사발생률이높음을확인하였다 (p=0.001, Table 4). 총 18명에대해상사근에대해수술하였으며, 안구심반사가발생한경우는없었다. 안구심반사가발생한 117명중 96명 (82.1%) 에서수술 5분 Table 3. Comparison of the occurrence of the oculocardiac reflex incidence between recession and resection procedure, lateral rectus muscle and medial rectus muscle OCR (+) (n = 117) OCR (-) (n = 270) p-value * Type of surgery Recession 66 (27.5) 174 (72.5) 0.297 Resection 5 (16.6) 25 (83.3) Type of rectus muscle Lateral rectus 60 (28.9) 147 (71.1) 0.910 Medial rectus 6 (18.1) 27 (81.9) Recession & Resection surgery include only rectus muscle. Lateral rectus surgery include bilateral lateral rectus recession, medial rectus surgery include bilateral & unilateral rectus recession. Values are presented as number (%). OCR = oculocardiac reflex. * Chi-square test. 이내에안구심반사가발생하였으며, 하사근과직근을동시에수술한경우 24명 (88.8%), 직근만단독으로수술한경우 72명 (80.0%) 에서수술 5분이내에안구심반사가발생하였다 (Fig. 1). 안구심반사가발생한총 117명의처치로는 27명 (23.1%) 에서발생 5분이내에정맥내에 Atropine (15 μg/kg) 을주사하였으며, 90명 (76.9%) 에서는특별한처치없이견인된근육을느슨하게해주었으며, 두군모두 5분이내심박동수는기본값의 15% 이내로회복되었으며, 수술종료후 20분간경과관찰을하였으며특별한심혈관계및안과 Table 4. Comparison of the oculocardiac reflex incidence between one muscle surgery and two muscle surgery OCR (+) OCR (-) p-value * Number of muscle Two muscle surgery 27 (52.9) 24 (50.0) 0.001 One muscle surgery 80 (27.7) 208 (73.0) One muscle surgery include rectus muscle, Two muscle surgery include inferior oblique muscle and rectus muscle. Values are presented as number (%). OCR = oculocardiac reflex. * Chi-square test. Figure 1. Comparison of the oculocardiac reflex occurence between within 5 minutes after surgery and after 5 minutes after surgery. One muscle surgery includes rectus muscle, two muscle surgery include inferior oblique muscle and rectus muscle. OCR = oculocardiac reflex; min = minute(s). 54
- 박형준 백혜정 : 사시수술중발생하는안구심반사 - 적합병증은나타나지않았다. 고찰 1908년 Aschner 19 와 Dagnini 20 에의해안구심반사라는개념이처음도입되었으며안구심반사에의한서맥은소아사시교정술후오심, 구토와통증조절과더불어주의깊게관찰해야할합병증이다. 1,21 안구심반사는연구자의정의기준에따라다른발생률을보이며, 심박수가기준치보다 10-20% 이상감소할경우또는심박수가분당 20회이상감소할경우를안구심반사가발생한것으로간주한다. 6,14,22,23 본연구에서는심박수가기준치에비해 15% 이상감소한경우를안구심반사가발생한것으로간주하였다. 안구심반사의발생빈도는한눈또는두눈수술에따라성별에따라차이가없음이여러논문을통해보고되었으며, 본연구에서도성별에따른안구심반사발생빈도는통계학적으로차이가없었다 (p=0.734). 7,18,24 여러연구에서환자의연령이증가함에따라안구심반사의빈도가감소한다는보고가있었으며, 소아인경우 9세이하에서잘발생한다는보고도있지만, 연령에따른유의한차이가없다는보고도있었다. 6,7,11,25 본연구에서연령에따른안구심반사의발생률은발생군 ( 평균 9.74 ± 5.01세 ), 비발생군 ( 평균 9.25 ± 8.29세 ) 로유의한차이를보이지는않았다 (p=0.119). 사시수술종류에따른안구심반사의빈도를살펴보면후전술을시행한군에서, 절제술을시행한군에비해안구심반사빈도가높다는보고가있었으며, 후전술과절제술을시행한군사이에발생빈도차이가없다는보고도있었다. 6,19 본연구에서는수술방법에따른안구심반사의발생빈도는유의한통계적차이가보이지않았다 (p=0.910). 외안근의종류에따른안구심반사발생빈도는연구자마다다르게보고되어, Mendelblatt et al, 26 Kim et al 7 은내직근을견인할때다른외안근을견인할때보다안구심반사의발생빈도가높다고보고하였고, Min et al 27 은내직근견인시에는외직근견인시보다안구심반사의발생빈도가통계학적으로높았지만, 내직근과하사근사이에는통계학적으로의미있는차이가없다고보고하였다. Aletaha et al 6 은회선수직근수술시에는직근수술시보다안구심반사의발생빈도가높았으며, 이는회선수직근에대한접근및수술적조작이직근수술보다어려운점을이유로설명하였다. Cho et al 13 은내직근술군과나머지외안근수술군간안구심반사의발생빈도는통계학적인차이가없다고보고하였으며, 본연구에서도외직근과내직근등직근종류에따른안구심반사의발생빈도는통계학적인차이가없었다 (p=0.910). 여러개의근육을동시에수술한경우근육순서에따른안구심반사발생률의차이가없다는보고가있었으나, 이와반대로 Lai et al, 14 Ha et al 18 은여러개의근육중첫번째근육수술시안구심반사발생률이높다고보고하였다. 7 본연구에서는직근과하사근을수술하는경우직근을단독으로수술하는경우보다안구심반사발생률이통계학적으로유의하게높았으며 (p=0.001), 직근과하사근을수술하는경우와직근을단독으로수술하는경우각각 24명 (88.8%), 72명 (80.0%) 에서수술할근육을찾아훅 (hook) 으로견인하는행위가주로일어나는수술시작후 5분이내에안구심반사가발생하였다. 직근과하사근을동시에수술하는경우모든수술에서하사근을먼저수술하고직근을수술하였으며이는하사근수술시안구심반사발생이더발생했음을알수있다. 본연구에서는근육에가해지는견인량을정량적으로측정하지못하였지만, Milot et al, 11 Min et al 27 은수술중근육에가해지는자극량을정량적으로측정하였으며, Milot et al 11 은수술하는근육에급격하고공격적인조작을최소화하여안구심반사발생률을줄일수있다고하였다. Min et al 27 은내직근, 하사근, 외직근순으로안구심반사를유발하는견인양의역치값이낮아수술시수술하는근육종류에따라견인양을최소화하여수술하는주의가필요하다고하였다. 수술전안구심반사의방지를위해여러방법이보고되었으며 Lee and Chang 28 은수술전 Tetracaine을국소점안함으로써, Berler 29 은수술전에구후마취를시행함으로써안구심반사발생을줄일수있다고보고하였다. 본연구에서는마취전처치로 Atropine이나 Glycopyrrolate 같은부교감신경차단제제를사용하지않았다. 이러한부교감신경차단제제를수술전사용하는것이수술중안구심반사를줄일수있다는보고가있지만, 소아에서 Atropine 투여시성인보다적은투여용량에도불구하고율동부정 (Dysrhythmia), 심실성빈맥 (Ventricular tachycardia) 등과같은위험한심전도상의변화가생길수있다는보고가있어, 예방적 Atropine 사용시환자의상태와수술방법에따라주의가필요함을알수있다. 2,10,24,30 부교감신경차단제제와더불어 Gallamine과같은근이완제를사용하는경우에도안구심반사를줄일수있다는보고가있으며, 수술전활차하신경차단을통해안구심반사를줄일수있다는보고도있다. 1,9 본연구의한계점으로는후향적분석이라는점과본연구의모든환자를단일술자가수술하였지만정량적으로근육에가해지는힘을측정하지못했다는점, 국내에서사시환자로진단받은환자중대다수가외사시며, 31 본연구 55
- 검안및콘택트렌즈학회지 2019 년제 18 권제 2 호 - 에도대상중외사시환자가양안수술로서외직근후전을단독으로한경우가많았다는것이한계점이라할수있겠다. 직근의종류에따라, 수술방법에따라안구심반사발생비율은무관하였으나특히직근과하사근의병행수술시수술 5분이내에첫번째근육의견인조작시안구심반사가유의하게발생함을알수있었다. 따라서두개이상의직근과하사근을병행수술할경우특히첫근육인하사근의확인, 박리및견인등의조작시좀더조심스럽게불필요한외력을가하지않도록노력하여사시수술중의안구심반사발생을최소화하는것이매우중요하다고판단되었다. REFERENCES 1) Choi YG, Park SW, Kim DO. Effects of gallamine, vecuronium and rocuruniu on oculocardiac reflex, blood pressure and heart rate in pediatric strabismus surgery. J Korean Ophthalmol Soc 2002;43:457-61. 2) Bosomworth PP, Ziegler CH, Jacoby J. The oculo-cardiac reflex in eye muscle surgery. Anesthesiology 1958;19:7-10. 3) Hahnenkamp K, Hönemann CW, Fischer LG, et al. Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery. Paediatr Anaesth 2000;10:601-8. 4) Sorenson EJ, Gilmore JE. Cardiac arrest during strabismus surgery: a preliminary report. Am J Ophthalmol 1956;41:748-52. 5) Smith RB, Douglas H, Petruscak J. The oculocardiac reflex and sino-atrial arrest. Can Anaesth Soc J 1972;19:138-42. 6) Aletaha M, Bagheri A, Roodneshin F, et al. Oculocardiac reflex during strabismus surgery: experience from a tertiary hospital. Strabismus 2016;24:74-8. 7) Kim HK, Yoon KC, Park YG. Oculocardiac reflex during strabismus surgery. J Korean Ophthalmol Soc 2003;44:896-903. 8) Blanc VF, Hardy JF, Milot J, Jacob JL. The oculocardiac reflex: a graphic and statistical analysis in infants and children. Can Anaesth Soc J 1983;30:360-9. 9) Kim SH, Shin HJ. Effects of an infratrochlear nerve block on reducing the oculocardiac reflex during strabismus surgery: a randomized controlled trial. Graefes Arch Clin Exp Ophthalmol 2018;256: 1777-82. 10) Mirakhur RK, Jones CJ, Dundee JW, Archer DB. I.m. or i.v. atropine or glycopyrrolate for the prevention of oculocardiac reflex in children undergoing squint surgery. Br J Anaesth 1982;54:1059-63. 11) Milot JA, Jacob JL, Blanc VF, Hardy JF. The oculocardiac reflex in strabismus surgery. Can J Ophthalmol 1983;18:314-7. 12) Apt L, Isenberg S, Gaffney WL. The oculocardiac reflex in strabismus surgery. Am J Ophthalmol 1973;76:533-6. 13) Cho JS, Kim DS, Shin JC. Oculocardiac reflex during strabismus surgery. J Korean Ophthalmol Soc 1998;39:3078-82. 14) Lai YH, Hsu HT, Wang HZ, et al. The oculocardiac reflex during strabismus surgery: its relationship to preoperative clinical eye findings and subsequent postoperative emesis. J AAPOS 2014;18: 151-5. 15) Allen LE, Sudesh S, Sandramouli S, et al. The association between the oculocardiac reflex and post-operative vomiting in children undergoing strabismus surgery. Eye (Lond) 1998;12(Pt 2):193-6. 16) Moonie GT, Rees DL, Elton D. The oculocardiag reflex during strabismus surgery. Can Anaesth Soc J 1964;11:621-32. 17) Na TY, Park SC. Relationship between nausea, vomiting and oculocardiac reflex developing after strabismus surgery under topical anesthesia. J Korean Ophthalmol Soc 1999;40:1391-5. 18) Ha SG, Huh J, Lee BR, Kim SH. Surgical factors affecting oculocardiac reflex during strabismus surgery. BMC ophthalmol 2018;18:103. 19) Aschner B. About a previously described reflex of eye on circulation and respiration: Disappearance of Radialispules pressure on the eye. Vienna Klin Wochenschr 1908;21:1552-9. 20) Dagnini G. Intornoad unriflection caused in hemiplegic aleuni collostimolo of corne ecoll pressure on the bulb oculars. Bulletin of Science and Medicine 1908;8:38. 21) You JG, Jang YH, Lee DH, et al. Postoperative nausea and vomiting after strabismus surgery in pediatrics: a comparison between VIMA with Sevoflurane and TIVA with propofol. Korean J Anesthesiol 2004;47:59-63. 22) Kang HG, Kim KH. Oculocardiac reflex during ptosis operation under local anesthesia. J Korean Ophthalmol Soc 2008;49:1-7. 23) Taylor C, Wilson FM, Roesch R, Stoelting VK. Prevention of the oculo-cardiac reflex in children comparison of retrobulbar block and intravenous atropine. Anesthesiology 1963;24:646-9. 24) Deacock AR, Oxer HF. The prevention of reflex bradycardia during ophthalmic surgery. Br J Anaesth 1962;34:451-7. 25) Clarke WN, Hodges E, Noel LP, et al. The oculocardiac reflex during ophthalmoscopy in premature infants. Am J Ophthalmol 1985;99:649-51. 26) Mendelblatt FI, Kirsch RE, Lemberg L. A study comparing methods of preventing the oculocardiac reflex. Am J Ophthalmol 1962;53:506-12. 27) Min BM, Park WC, Kim CS. The quantiative measurement of the oculocardiac reflex. J Korean Ophthalmol Soc 1988;29:625-9. 28) Lee GW, Chang BL. The effect of topical anesthesia on the oculocardiac reflex. J Korean Ophthalmol Soc 1986;27:829-32. 29) Berler DK. The oculocardiac reflex. Am J Ophthalmol 1963;56: 954-9. 30) Dauchot P, Gravenstein JS. Effects of atropine on the electrocardiogram in different age groups. Clin Pharmacol Ther 1971;12: 274-80. 31) Han KE, Baek SH, Kim SH, et al. Prevalence and risk factors of strabismus in children and adolescents in South Korea: Korea National Health and Nutrition Examination Survey, 2008-2011. PLoS One 2018;13:e0191857. 56