본문 바로가기
KERD
논문KCI 등재

Precision Medicine Approach to Cochlear Implantation

최병윤|김예리
대한이비인후과학회 (Korean Society of Otorhinolaryngology-Head and Neck Surgery)|2022.11|Clinical and Experimental Otorhinolaryngology|제15권 제4호|pp. 299-309|DOI https://doi.org/10.21053/ceo.2022.01382

2

조회

0

다운로드

0

인용

0

참고문헌

키워드

Precision MedicineHearing LossCochlear ImplantationGenotype-Phenotype CorrelationCochlear ParametersEtiology of Hearing Loss

초록

In the early days of cochlear implantation (CI) surgery, when the types of electrodes were limited and the etiology of sensorineural hearing loss (SNHL) was not well understood, the one-size-fits-all approach to CI held true, as in all other fields. However, in the era of personalized medicine, there have been attempts to associate CI performance with the etiology of SNHL and to establish customized surgical techniques that can maximize performance according to individual cochlear dimensions. Personalized genomic-driven assessments of CI candidates and a better understanding of genotype-phenotype correlations could provide clinically applicable diagnostic and prognostic information about questions such as who, how, and when to implant. Rigorous and strategic imaging assessments also provide better insights into the anatomic etiology of SNHL and cochlear dimensions, leading to individualized surgical techniques to augment CI outcomes. Furthermore, the precision medicine approach to CI is not necessarily limited to preoperative planning, but can be extended to either intraoperative electrode positioning or even the timing of the initial switch-on. In this review, we discuss the implications of personalized diagnoses (both genetic and nongenetic) on the planning and performance of CI in patients with prelingual and postlingual SNHL.

Abstract

In the early days of cochlear implantation (CI) surgery, when the types of electrodes were limited and the etiology of sensorineural hearing loss (SNHL) was not well understood, the one-size-fits-all approach to CI held true, as in all other fields. However, in the era of personalized medicine, there have been attempts to associate CI performance with the etiology of SNHL and to establish customized surgical techniques that can maximize performance according to individual cochlear dimensions. Personalized genomic-driven assessments of CI candidates and a better understanding of genotype-phenotype correlations could provide clinically applicable diagnostic and prognostic information about questions such as who, how, and when to implant. Rigorous and strategic imaging assessments also provide better insights into the anatomic etiology of SNHL and cochlear dimensions, leading to individualized surgical techniques to augment CI outcomes. Furthermore, the precision medicine approach to CI is not necessarily limited to preoperative planning, but can be extended to either intraoperative electrode positioning or even the timing of the initial switch-on. In this review, we discuss the implications of personalized diagnoses (both genetic and nongenetic) on the planning and performance of CI in patients with prelingual and postlingual SNHL.

참고문헌 (107)

  1. Tomblin JB, "A comparison of language achievement in children with cochlear implants and children using hearing aids", J Speech Lang Hear Res, 42(2), pp.497~509 (1999)
  2. Blamey P, "Factors affecting auditory performance of postlinguistically deaf adults using cochlear implants : an update with 2251 patients", Audiol Neurootol, 18(1), pp.36~47 (2013)
  3. Moberly AC, "The enigma of poor performance by adults with cochlear implants", Otol Neurotol, 37(10), pp.1522~1528 (2016)
  4. Archbold SM, "Long-term use of cochlear implant systems in paediatric recipients and factors contributing to non-use", Cochlear Implants Int, 10(1), pp.25~40 (2009)
  5. Raine CH, "The cost and analysis of nonuse of cochlear implants", Otol Neurotol, 29(2), pp.221~224 (2008)
  6. Lee CY, "Comprehensive etiologic analyses in pediatric cochlear implantees and the clinical implications", Biomedicines, 10(8), pp.1846~ (2022)
  7. Nishio SY, "Etiology of hearing loss affects auditory skill development and vocabulary development in pediatric cochlear implantation cases", Acta Otolaryngol, 142(3-4), pp.308~315 (2022)
  8. Lee SY, "The molecular etiology of deafness and auditory performance in the postlingually deafened cochlear implantees", Sci Rep, 10(1), pp.5768~ (2020)
  9. Rak K, "Influence of cochlear parameters on the current practice in cochlear implantation: development of a concept for personalized medicine", HNO, 69(Suppl 1), pp.24~30 (2021)
  10. Lee SY, "Modiolar proximity of slim modiolar electrodes and cochlear duct length : correlation for potential basis of customized cochlear implantation with perimodiolar electrodes", Ear Hear, 42(2), pp.323~333 (2021)
  11. Miyagawa M, "Massively parallel DNA sequencing successfully identifies new causative mutations in deafness genes in patients with cochlear implantation and EAS", PLoS One, 8(10), pp.e75793~ (2013)
  12. Park JH, "Outcome of cochlear implantation in prelingually deafened children according to molecular genetic etiology", Ear Hear, 38(5), pp.e316~e324 (2017)
  13. Wu CC, "Identifying children with poor cochlear implantation outcomes using massively parallel sequencing", Medicine(Baltimore), 94(27), pp.e1073~ (2015)
  14. Wu CM, "Long-term cochlear implant outcomes in children with GJB2 and SLC26A4 mutations", PLoS One, 10(9), pp.e0138575~ (2015)
  15. Rodriguez-Ballesteros M, "Auditory neuropathy in patients carrying mutations in the otoferlin gene(OTOF)", Hum Mutat, 22(6), pp.451~456 (2003)
  16. Sharma A, "Cortical development and neuroplasticity in auditory neuropathy spectrum disorder", Hear Res, 330(Pt B), pp.221~232 (2015)
  17. Lee SY, "Central auditory maturation and behavioral outcomes after cochlear implantation in prelingual auditory neuropathy spectrum disorder related to OTOF variants(DFNB9) : lessons from pilot study", PLoS One, 16(6), pp.e0252717~ (2021)
  18. Liu Y, "Effect of age at cochlear implantation on auditory and speech development of children with auditory neuropathy spectrum disorder", Auris Nasus Larynx, 41(6), pp.502~506 (2014)
  19. Kim BJ, "Mutational and phenotypic spectrum of OTOF-related auditory neuropathy in Koreans : eliciting reciprocal interaction between bench and clinics", J Transl Med, 16(1), pp.330~ (2018)
  20. Philips B, "Cochlear implants in children deafened by congenital cytomegalovirus and matched Connexin 26 peers", Int J Pediatr Otorhinolaryngol, 78(3), pp.410~415 (2014)
  21. Lee DJ, "Effects of cytomegalovirus(CMV)related deafness on pediatric cochlear implant outcomes", Otolaryngol Head Neck Surg, 133(6), pp.900~905 (2005)
  22. Laccourreye L, "Speech perception, production and intelligibility in French-speaking children with profound hearing loss and early cochlear implantation after congenital cytomegalovirus infection", Eur Ann Otorhinolaryngol Head Neck Dis, 132(6), pp.317~320 (2015)
  23. Han JJ, "Prediction of the outcome of cochlear implantation in the patients with congenital cytomegalovirus infection based on magnetic resonance imaging characteristics", J Clin Med, 8(2), pp.136~ (2019)
  24. Vlastarakos PV, "Cochlear implantation update : contemporary preoperative imaging and future prospects : the dual modality approach as a standard of care", Expert Rev Med Devices, 7(4), pp.555~567 (2010)
  25. Yousef M, "Audiologic outcome of cochlear implantation in children with cochlear nerve deficiency", Otol Neurotol, 42(1), pp.38~46 (2021)
  26. Valero J, "Electrophysiologic and behavioral outcomes of cochlear implantation in children with auditory nerve hypoplasia", Ear Hear, 33(1), pp.3~18 (2012)
  27. Incerti PV, "Programming characteristics of cochlear implants in children: effects of aetiology and age at implantation", Int J Audiol, 57(sup2), pp.S27~S40 (2018)
  28. Sunwoo W, "Effect of initial switch-on within 24 hours of cochlear implantation using slim modiolar electrodes", Sci Rep, 11(1), pp.22809~ (2021)
  29. Kim Y, "Tight modiolar proximity and feasibility of slim modiolar cochlear implant electrode array insertion in diverse etiologies of hearing loss", Eur Arch Otorhinolaryngol, 279(8), pp.3899~3909 (2022)
  30. 이상연, "Potential Implications of Slim Modiolar Electrodes for Severely Malformed Cochleae: A Comparison With the Straight Array With Circumferential Electrodes", Clinical and Experimental Otorhinolaryngology, 14(3), pp.287~294 (2021), 대한이비인후과학회[DOI]
  31. 배성훈, "Cochlear Implants for Patients With Common Cavity Deformities and the Impact of Electrode Positioning", Clinical and Experimental Otorhinolaryngology, 15(1), pp.77~83 (2022), 대한이비인후과학회[DOI]
  32. Shearer AE, "Genetic variants in the peripheral auditory system significantly affect adult cochlear implant performance", Hear Res, 348, pp.138~142 (2017)
  33. Vermeire K, "Good speech recognition and quality-of-life scores after cochlear implantation in patients with DFNA9", Otol Neurotol, 27(1), pp.44~49 (2006)
  34. Pecci A, "Cochlear implantation is safe and effective in patients with MYH9-related disease", Orphanet J Rare Dis, 9, pp.100~ (2014)
  35. Eppsteiner RW, "Prediction of cochlear implant performance by genetic mutation: the spiral ganglion hypothesis", Hear Res, 292(1-2), pp.51~58 (2012)
  36. Miyagawa M, "The patients associated with TMPRSS3 mutations are good candidates for electric acoustic stimulation", Ann Otol Rhinol Laryngol, 124(Suppl 1), pp.193S~204S (2015)
  37. Tolisano AM, "Cochlear implantation in patients with neurofibromatosis type 2", Otol Neurotol, 40(4), pp.e381~e385 (2019)
  38. Kim TB, "A gene responsible for autosomal dominant auditory neuropathy(AUNA1)maps to 13q14-21", J Med Genet, 41(11), pp.872~876 (2004)
  39. Ruel J, "Impairment of SLC17A8 encoding vesicular glutamate transporter-3, VGLUT3, underlies nonsyndromic deafness DFNA25 and inner hair cell dysfunction in null mice", Am J Hum Genet, 83(2), pp.278~292 (2008)
  40. Chen DY, "A dominant variant in DMXL2 is linked to nonsyndromic hearing loss", Genet Med, 19(5), pp.553~558 (2017)
  41. Jang MW, "Nonsense TMEM43 variant leads to disruption of connexin-linked function and autosomal dominant auditory neuropathy spectrum disorder", Proc Natl Acad Sci U S A, 118(22), pp.e2019681118~ (2021)
  42. Han KH, "ATP1A3 mutations can cause progressive auditory neuropathy : a new gene of auditory synaptopathy", Sci Rep, 7(1), pp.16504~ (2017)
  43. Santarelli R, "OPA1-related auditory neuropathy: site of lesion and outcome of cochlear implantation", Brain, 138(Pt 3), pp.563~576 (2015)
  44. Kim BJ, "Outcome of cochlear implantation in NLRP3-related autoinflammatory inner ear disorders", Otol Neurotol, 42(2), pp.e168~e171 (2021)
  45. Holder JT, "Cochlear implantation and electric acoustic stimulation in children with TMPRSS3 genetic mutation", Otol Neurotol, 42(3), pp.396~401 (2021)
  46. Kim Y, "Molecular aetiology of ski-slope hearing loss and audiological course of cochlear implantees", Eur Arch Otorhinolaryngol, 279(10), pp.4871~4882 (2022)
  47. Yoshimura H, "Genetic testing has the potential to impact hearing preservation following cochlear implantation", Acta Otolaryngol, 140(6), pp.438~444 (2020)
  48. Ramos de Miguel A, "Evaluation of intracochlear position of a slim modiolar electrode array, by using different radiological analyses", Otol Neurotol, 40(5S Suppl 1), pp.S10~S17 (2019)
  49. Riemann C, "The pull-back technique for the 532 slim modiolar electrode", Biomed Res Int, 2019, pp.6917084~ (2019)
  50. Shearer AE, "Comprehensive genetic testing for hereditary hearing loss using massively parallel sequencing", Proc Natl Acad Sci U S A, 107(49), pp.21104~21109 (2010)
  51. Brownstein Z, "Targeted genomic capture and massively parallel sequencing to identify genes for hereditary hearing loss in Middle Eastern families", Genome Biol, 12(9), pp.R89~ (2011)
  52. Black J, "Prognostic indicators in paediatric cochlear implant surgery : a systematic literature review", Cochlear Implants Int, 12(2), pp.67~93 (2011)
  53. Park JH, "Exploration of molecular genetic etiology for Korean cochlear implantees with severe to profound hearing loss and its implication", Orphanet J Rare Dis, 9, pp.167~ (2014)
  54. Wu CC, "Predominance of genetic diagnosis and imaging results as predictors in determining the speech perception performance outcome after cochlear implantation in children", Arch Pediatr Adolesc Med, 162(3), pp.269~276 (2008)
  55. Yan YJ, "The effect of GJB2 and SLC26A4 gene mutations on rehabilitative outcomes in pediatric cochlear implant patients", Eur Arch Otorhinolaryngol, 270(11), pp.2865~2870 (2013)
  56. Yoshida H, "Long term speech perception after cochlear implant in pediatric patients with GJB2 mutations", Auris Nasus Larynx, 40(5), pp.435~439 (2013)
  57. Delmaghani S, "Hypervulnerability to sound exposure through impaired adaptive proliferation of peroxisomes", Cell, 163(4), pp.894~906 (2015)
  58. Kenneson A, "Review and meta-analysis of the epidemiology of congenital cytomegalovirus(CMV)infection", Rev Med Virol, 17(4), pp.253~276 (2007)
  59. Manicklal S, "The “silent” global burden of congenital cytomegalovirus", Clin Microbiol Rev, 26(1), pp.86~102 (2013)
  60. Fowler KB, "Congenital cytomegalovirus(CMV)infection and hearing deficit", J Clin Virol, 35(2), pp.226~231 (2006)
  61. Stagno S, "Primary cytomegalovirus infection in pregnancy : incidence, transmission to fetus, and clinical outcome", JAMA, 256(14), pp.1904~1908 (1986)
  62. Goderis J, "Hearing loss and congenital CMV infection : a systematic review", Pediatrics, 134(5), pp.972~982 (2014)
  63. Goderis J, "Hearing in children with congenital cytomegalovirus infection : results of a longitudinal study", J Pediatr, 172, pp.110~115.e2 (2016)
  64. Medearis DN, "Viral infections during pregnancy and abnormal human development", Am J Obstet Gynecol, 90(7), pp.1140~1148 (1964)
  65. Kim BJ, "Characterization of detailed audiological features of cytomegalovirus infection : a composite cohort study from groups with distinct demographics", Biomed Res Int, 2018, pp.7087586~ (2018)
  66. Sohn YM, "Congenital cytomegalovirus infection in Korean population with very high prevalence of maternal immunity", J Korean Med Sci, 7(1), pp.47~51 (1992)
  67. Barkai G, "Universal neonatal cytomegalovirus screening using saliva : report of clinical experience", J Clin Virol, 60(4), pp.361~366 (2014)
  68. Ramirez Inscoe JM, "Cochlear implantation in children deafened by cytomegalovirus : speech perception and speech intelligibility outcomes", Otol Neurotol, 25(4), pp.479~482 (2004)
  69. Iwasaki S, "Cochlear implant in children with asymptomatic congenital cytomegalovirus infection", Audiol Neurootol, 14(3), pp.146~152 (2009)
  70. Matsui T, "Outcome of cochlear implantation in children with congenital cytomegalovirus infection or GJB2 mutation", Acta Otolaryngol, 132(6), pp.597~602 (2012)
  71. Ciorba A, "Rehabilitation and outcome of severe profound deafness in a group of 16 infants affected by congenital cytomegalovirus infection", Eur Arch Otorhinolaryngol, 266(10), pp.1539~1546 (2009)
  72. Malik V, "Outcome of cochlear implantation in asymptomatic congenital cytomegalovirus deafened children", Laryngoscope, 121(8), pp.1780~1784 (2011)
  73. Viccaro M, "Long-term follow-up of implanted children with cytomegalovirus-related deafness", Audiol Neurootol, 17(6), pp.395~399 (2012)
  74. Casselman JW, "Aplasia and hypoplasia of the vestibulocochlear nerve : diagnosis with MR imaging", Radiology, 202(3), pp.773~781 (1997)
  75. Glastonbury CM, "Imaging findings of cochlear nerve deficiency", AJNR Am J Neuroradiol, 23(4), pp.635~643 (2002)
  76. McClay JE, "Evaluation of pediatric sensorineural hearing loss with magnetic resonance imaging", Arch Otolaryngol Head Neck Surg, 134(9), pp.945~952 (2008)
  77. Birman CS, "Cochlear implant outcomes in cochlea nerve aplasia and hypoplasia", Otol Neurotol, 37(5), pp.438~445 (2016)
  78. Ozdogmus O, "Connections between the facial, vestibular and cochlear nerve bundles within the internal auditory canal", J Anat, 205(1), pp.65~75 (2004)
  79. Thai-Van H, "Functional magnetic resonance imaging may avoid misdiagnosis of cochleovestibular nerve aplasia in congenital deafness", Am J Otol, 21(5), pp.663~670 (2000)
  80. Acker T, "Is there a functioning vestibulocochlear nerve? Cochlear implantation in a child with symmetrical auditory findings but asymmetric imaging", Int J Pediatr Otorhinolaryngol, 57(2), pp.171~176 (2001)
  81. Buchman CA, "Cochlear implantation in children with labyrinthine anomalies and cochlear nerve deficiency : implications for auditory brainstem implantation", Laryngoscope, 121(9), pp.1979~1988 (2011)
  82. Young NM, "Pediatric cochlear implantation of children with eighth nerve deficiency", Int J Pediatr Otorhinolaryngol, 76(10), pp.1442~1448 (2012)
  83. Shelton C, "The narrow internal auditory canal in children : a contraindication to cochlear implants", Otolaryngol Head Neck Surg, 100(3), pp.227~231 (1989)
  84. Brotto D, "Epidemiologic, imaging, audiologic, clinical, surgical, and prognostic issues in common cavity deformity : a narrative review", JAMA Otolaryngol Head Neck Surg, 145(1), pp.72~78 (2019)
  85. Kim BJ, "How to maximize the outcomes of cochlear implantation in common cavity and cochlear aplasia with dilated vestibule, the most severe inner ear anomalies?", Clin Exp Otorhinolaryngol, 15(1), pp.3~4 (2022)
  86. Alhabib SF, "Audiological and speech performance after cochlear implantation in cochlear aplasia deformity", Cureus, 13(7), pp.e16654~ (2021)
  87. Jeong SW, "Cochlear implantation in children with cochlear aplasia", Acta Otolaryngol, 132(9), pp.910~915 (2012)
  88. Graham JM, "Congenital malformations of the ear and cochlear implantation in children: review and temporal bone report of common cavity", J Laryngol Otol Suppl, 114(S25), pp.1~14 (2000)
  89. Yamazaki H, "Electrically evoked auditory brainstem response-based evaluation of the spatial distribution of auditory neuronal tissue in common cavity deformities", Otol Neurotol, 35(8), pp.1394~1402 (2014)
  90. Wei X, "Application of multiplanar volume reconstruction technique for the assessment of electrode location and analysis of the correlation to cochlear programming and performance in common cavity deformity", Front Neurol, 12, pp.783225~ (2022)
  91. Miyagawa M, "A comprehensive study on the etiology of patients receiving cochlear implantation with special emphasis on genetic epidemiology", Otol Neurotol, 37(2), pp.e126~e134 (2016)
  92. Michalski N, "Genes involved in the development and physiology of both the peripheral and central auditory systems", Annu Rev Neurosci, 42, pp.67~86 (2019)
  93. Agostini L, "NALP3 forms an IL-1beta-processing inflammasome with increased activity in Muckle-Wells autoinflammatory disorder", Immunity, 20(3), pp.319~325 (2004)
  94. Kim YH, "Long-term efficacy of anakinra in cryopyrin-associated periodic syndrome : focus on destructive arthropathy", J Clin Immunol, 41(8), pp.1936~1939 (2021)
  95. Kim BJ, "Otological aspects of NLRP3-related autoinflammatory disorder focusing on the responsiveness to anakinra", Rheumatology(Oxford), 60(3), pp.1523~1532 (2021)
  96. Choi BY, "Diagnostic application of targeted resequencing for familial nonsyndromic hearing loss", PLoS One, 8(8), pp.e68692~ (2013)
  97. Shearer AE, "Hereditary hearing loss and deafness overview" (2017), University of Washington
  98. Roland JT, "Long-term outcomes of cochlear implantation in patients with high-frequency hearing loss", Laryngoscope, 128(8), pp.1939~1945 (2018)
  99. Shew MA, "Long-term hearing preservation and speech perception performance outcomes with the slim modiolar electrode", Otol Neurotol, 42(10), pp.e1486~e1493 (2021)
  100. Haber K, "The influence of slim modiolar electrode on residual hearing in pediatric patients", Eur Arch Otorhinolaryngol, 278(8), pp.2723~2732 (2021)
  101. O’Connell BP, "Insertion depth impacts speech perception and hearing preservation for lateral wall electrodes", Laryngoscope, 127(10), pp.2352~2357 (2017)
  102. Chakravorti S, "Further evidence of the relationship between cochlear implant electrode positioning and hearing outcomes", Otol Neurotol, 40(5), pp.617~624 (2019)
  103. Dhanasingh A, "An overview of cochlear implant electrode array designs", Hear Res, 356, pp.93~103 (2017)
  104. Dhanasingh A., "Cochlear duct length along the outer wall vs organ of corti: which one is relevant for the electrode array length selection and frequency mapping using Greenwood function?", World J Otorhinolaryngol Head Neck Surg, 5(2), pp.117~121 (2018)
  105. Escude B, "The size of the cochlea and predictions of insertion depth angles for cochlear implant electrodes", Audiol Neurootol, 11(Suppl 1), pp.27~33 (2006)
  106. Zahara D, "Variations in cochlear size of cochlear implant candidates", Int Arch Otorhinolaryngol, 23(2), pp.184~190 (2019)
  107. Grover M, "Measuring cochlear duct length in Asian population: worth giving a thought!", Eur Arch Otorhinolaryngol, 275(3), pp.725~728 (2018)

관련 논문AI추천

Application of Genetic Information to Cochlear Implantation in Clinical PracticeWu Chen-Chi대한청각학회 · Journal of Audiology & Otology2024 · 제28권 제2호Current Issues With Pediatric Cochlear ImplantationFujiwara Rance J.T., Lee Kenneth H., Tan Donald대한청각학회 · Journal of Audiology & Otology2024 · 제28권 제2호Cochlear Implants for Patients With Common Cavity Deformities and the Impact of Electrode Positioning배성훈, 최재영, 최지훈대한이비인후과학회 · Clinical and Experimental Otorhinolaryngology2022 · 제15권 제1호Prediction of Cochlear Implant Outcomes in Patients With Prelingual Deafness강동훈, 이규엽, 이명진, 이상훈, 장정훈대한이비인후과학회 · Clinical and Experimental Otorhinolaryngology2016 · 제9권 제3호Genetic Characteristics and Audiological Performance After Cochlear Implantation in Patients With Incomplete Partition Type III김은경, 문인석, 이세아, 정진세, 지헌영, 최재영대한이비인후과학회 · Clinical and Experimental Otorhinolaryngology2023 · 제16권 제4호Potential Implications of Slim Modiolar Electrodes for Severely Malformed Cochleae: A Comparison With the Straight Array With Circumferential Electrodes이상연, 최병윤대한이비인후과학회 · Clinical and Experimental Otorhinolaryngology2021 · 제14권 제3호

이 간행물의 다른 논문 (11건)

Expanding Indications: Balloon Dilation of the Eustachian Tube for Patients Undergoing Surgery for Chronic Otitis Media김소영pp. 295-296Prediction of Occult Lymph Node Metastasis in Early Tongue Cancer권민수pp. 297-298The Role of Viruses in the Inception of Chronic RhinosinusitisSophia J Volpe, Hyeon Seung Lee, Eugene H Changpp. 310-318Long-term Changes of Hearing Thresholds and Eustachian Tube Function After Balloon Dilation of the Eustachian Tube in Patients With Chronic Otitis Media정종우, 안중호, 강우석, 박홍주, 하승철, 최연주, 이상훈pp. 319-325Factors Affecting the Extrusion Rate and Complications After Ventilation Tube Insertion: A Multicenter Registry Study on the Effectiveness of Ventilation Tube Insertion in Pediatric Patients With Chronic Otitis Media With Effusion—Part II김동기, 박홍주, 문인석, 조양선, 정연훈, 유명훈, 전범조, 여승근, 이준호, 이승환, 이지혜, 정재호, 박시내, 정종우, 서재현, 김규성, 최준, 한규철, 이규엽pp. 326-334
원문 보기